Linux Kernel Drivers for ev3dev-stretch¶

This is the documentation for the ev3dev-specific Linux kernel drivers that are part of the ev3dev-stretch operating system.

The drivers use sysfs to interact with user space (user space is anything outside of the kernel). Each hardware device is represented by a directory in sysfs called a device node. Each device node has attributes that are represented by files. You monitor and control the hardware by reading and writing these attribute files.

Sensors / Input Devices¶

The EV3 has four input ports for connecting sensors and other devices (like sensor multiplexers or motor controllers). If you are trying to use something that plugs into one of those ports, you are in the right place.

Supported Sensors¶

This is a list of sensors that currently have drivers available in the ev3dev kernel. The Part Number column links to the vendor website. The Name column links to the sensor’s entry in Appendix A.

Part Number	Name	Driver	Type	Auto-detect
	Generic EV3 Analog Sensor	`ev3-analog-XX`	EV3/Analog	Y
	Generic NXT Analog Sensor	`nxt-analog`	NXT/Analog	Y
Charmed Labs
Pixy LEGO	Pixy (CMUcam5) for LEGO	`pixy-lego`	NXT/I2C	Y
Dexter Industries
dFlex	Flexible Sensor for Mindstorms NXT	`di-dflex`	NXT/Analog	N [5]
Fatcatlab
9DOF Sensor	9DOF Sensor	`fcl-9dof`	EV3/UART	Y
ADC Adapter	ADC Adapter	`fcl-adc`	EV3/UART	Y
Altitude Sensor	Altitude Sensor	`fcl-altitude`	EV3/UART	Y
Gesture Sensor	Gesture Sensor	`fcl-gesture`	EV3/UART	Y
Humidity Sensor	Humidity Sensor	`fcl-humidity`	EV3/UART	Y
IR Receiver	IR Receiver	`fcl-ir`	EV3/UART	Y
Light Sensor	Light Sensor	`fcl-light`	EV3/UART	Y
HiTechnic
	NXT Color Sensor	`ht-nxt-color`	NXT/I2C	Y
NAA1030	NXT Angle Sensor	`ht-nxt-angle`	NXT/I2C	Y
NAC1040	NXT Acceleration / Tilt Sensor	`ht-nxt-accel`	NXT/I2C	Y
NBR1036	NXT Barometric Sensor	`ht-nxt-barometric`	NXT/I2C	Y
NCO1038	NXT Color Sensor V2	`ht-nxt-color-v2`	NXT/I2C	Y
NEO1048	NXT EOPD	`ht-nxt-eopd`	NXT/Analog	N [2]
NFS1074	NXT Force Sensor	`ht-nxt-force`	NXT/Analog	N [2]
NGY1044	NXT Gyro Sensor	`ht-nxt-gyro`	NXT/Analog	N [2]
NIL1046	NXT IRLink Sensor	`ht-nxt-ir-link`	NXT/I2C	Y
NIR1032	NXT IRReceiver Sensor	`ht-nxt-ir-receiver`	NXT/I2C	Y
NIS1070	NXT PIR Sensor	`ht-nxt-pir`	NXT/I2C	Y
NMC1034	NXT Compass Sensor	`ht-nxt-compass`	NXT/I2C	Y
NMS1035	NXT Magnetic Sensor	`ht-nxt-mag`	NXT/Analog	N [2]
NSK1042	NXT IRSeeker V2	`ht-nxt-ir-seek-v2`	NXT/I2C	Y
NSX2020	NXT Sensor Multiplexer	`ht-nxt-smux`	NXT/I2C	Y
SPR2010	NXT SuperPro Prototype Board	`ht-super-pro`	NXT/I2C	Y
LEGO
45504	EV3 Ultrasonic Sensor	`lego-ev3-us`	EV3/UART	Y
45505	EV3 Gyro Sensor	`lego-ev3-gyro`	EV3/UART	Y
45506	EV3 Color Sensor	`lego-ev3-color`	EV3/UART	Y
45507	EV3 Touch Sensor	`lego-ev3-touch`	EV3/Analog	Y
45509	EV3 Infrared Sensor	`lego-ev3-ir`	EV3/UART	Y
9581	WeDo USB Hub	`wedo-hub`	USB	Y
9583	WeDo Motion Sensor	`wedo-motion`	Wedo/Analog	Y
9584	WeDo Tilt Sensor	`wedo-tilt`	Wedo/Analog	Y
9668	Energy Display	`lego-power-storage`	NXT/I2C	Y
9749	NXT Temperature Sensor	`lego-nxt-temp`	NXT/I2C	Y
9843	NXT Touch Sensor	`lego-nxt-touch`	NXT/Analog	Y [1]
9844	NXT Light Sensor	`lego-nxt-light`	NXT/Analog	Y
9845	NXT Sound Sensor	`lego-nxt-sound`	NXT/Analog	N [2]
9846	NXT Ultrasonic Sensor	`lego-nxt-us`	NXT/I2C	Y
Microinfinity
CruizCore XG 1300L	Digital Gyroscope And Accelerometer	`mi-xg1300l`	NXT/I2C	N [4]
mindsensors.com
AbsoluteIMU(-A/C/G)	Gyro, MultiSensitivity Accelerometer and Compass	`ms-absolute-imu`	NXT/I2C	Y
AngleSensor	GlideWheel-AS	`ms-angle`	NXT/I2C	Y
EV3SensorMUX	EV3 Sensor Multiplexer	`ms-ev3-smux`	NXT/I2C	Y
LightSensorArray	Light Sensor Array	`ms-light-array`	NXT/I2C	Y
LineLeader	Line Follower Sensor	`ms-line-leader`	NXT/I2C	Y
NXTCam-v4	Vision Subsystem v4 for NXT or EV3	`ms-nxtcam`	NXT/I2C	Y
NXTMMX-v2	Multiplexer for NXT/EV3 Motors	`ms-nxtmmx`	NXT/I2C	Y
NxtServo	8-channel Servo Controller	`ms-8ch-servo`	NXT/I2C	Y
PCF8574-Nx	Sensor building kit for NXT with PCF8574 IC	`pcf8574`	Other/I2C	N [3]
PCF8591-Nx	Sensor building kit for NXT with PCF8591 IC	`pcf8591`	Other/I2C	N [3]
PPS58-Nx	Digital Pneumatic Pressure Sensor	`ms-pps58-nx`	NXT/I2C	Y
PixyAdapter	Pixy Adapter for MINDSTORMS EV3 or NXT	`ms-pixy-adapter`	NXT/I2C	Y
RTC-Nx-v3	Realtime Clock for NXT	`ds1307`	Other/I2C	N [3]
TouchMux	Touch Sensor Multiplexer for NXT & EV3	`ms-nxt-touch-mux`	NXT/Analog	N [2]

[1]	Only touch sensors that shipped with the NXT 2.0 set can be automatically detected. Older touch sensors that shipped with the original NXT sets are missing an electrical connection (pin 2 is not internally connected to pin 3) and cannot be automatically detected.

[2] (1, 2, 3, 4, 5, 6) The automatic detection algorithm detects this sensor as an NXT/Analog type sensor but it cannot determine the exact sensor type. The generic analog driver (nxt-analog) will be loaded by default for this sensor. See the The lego-port Subsystem for information on how to manually load the correct driver.

[3]

(1, 2, 3) The automatic detection algorithm detects this sensor as an I2C sensor and the port is automatically put into I2C mode. However, the sensor does not follow the LEGO MINDSTORMS convention for I2C sensors, so the exact type of sensor cannot be determined. See Appendix C: I2C Devices for information on how to manually load the correct driver.

[4]	The automatic detection algorithm detects this sensor as an I2C sensor and the port is automatically put into I2C mode. However, this sensor only partially follows the LEGO MINDSTORMS convention for I2C sensors, so the driver must be loaded manually. See the sensor’s page for more information.

[5]	The Dexter Industries dFlex sensor cannot be automatically detected (because pin 2 is not connected to pin 3). In order to use this sensor, you must manually set the port to `nxt-analog` mode and then set the driver to `di-dflex`.

Unsupported Sensors¶

One of the goals of ev3dev is to support as many sensors as possible. In fact, even if a manufacturer’s documentation says that a device does not work with the EV3, chances are it will work with ev3dev.

If you have a sensor that is not supported yet, let us know about it by opening an issue on GitHub. For many sensors adding a driver is trivial - even if you are not a “kernel hacker” or a “c programmer”. For the non-trivial sensors, see the contributing page for information on how to write a driver or how to donate hardware to someone who will.

Using Sensors¶

Automatic Detection¶

The EV3 has “smart” sensor ports that can identify most sensors. Beware! Full automatic detection works on EV3 only. And even on EV3, some sensors cannot be automatically detected. See notes below in the table of supported sensors.

For sensors that cannot be automatically detected, you can manually control the input port mode. Read more about it on Input / Output Ports page.

On FatcatLab’s EVB, EV3/Analog and EV3/UART sensors can be automatically detected. For NXT/Analog sensors, you must manually set the mode. Most NXT/I2C sensors should be automatically detected.

On BrickPi, BrickPi+ and BrickPi3, sensors cannot be automatically detected at all. You must manually configure the input ports for all sensors.

On PiStorms, detection of EV3/UART, EV3/Analog and NXT/I2C sensors is semi-automatic. If you put the input port into ev3-uart, ev3-analog, or i2c-thru mode, the specific type of sensor will be automatically detected (assuming it is a LEGO compatible sensor). So you usually don’t have to write to the set_device attribute of the port for these sensors.

MINDSTORMS Compatible Sensors¶

Most of the supported sensors are designed to work with LEGO MINDSTORMS. These sensors use the LEGO sensor class. You can find these in sysfs at /sys/class/lego-sensor/. The sensors have modes that select what type of data is read from the sensor. Generally, you will select a mode and then read the data value from the sensor. Follow the link above for more details.

Other Sensors and Advanced Usage¶

Many sensors that were not specifically designed for LEGO MINDSTORMS can be used with ev3dev too. You can read more about the “Other” sensor types below. Also, some MINDSTORMS compatible sensor may have advanced features that are not accessible using the lego-sensor class.

When using sensors this way, often automatic detection will not work correctly, therefore it is usually best to manually select the mode of input port (e.g. other-i2c or other-uart).

For more information on using I2C sensors, check out Appendix C: I2C Devices.

Types of Sensors¶

When dealing with sensors in ev3dev, it is useful to know how it communicates with the EV3 brick. There are three basic kinds of communication that the input ports can use to get information from the sensor, Analog Sensors, I2C Sensors and UART Sensors, plus one special type for LEGO NXT Color Sensors.

Analog Sensors¶

These are the simplest type of sensor. The measured value is converted to a voltage (0-5VDC) that is read by the EV3.

EV3/Analog Sensors¶

These are sensors that were designed specifically for the EV3 and will not work on the NXT because the pinout is different. They contain an ID resistor so that the EV3 can tell different types of sensors apart. The actual analog value is measured on pin6.

NXT/Analog Sensors¶

These sensors are designed for the NXT, but also work on the EV3. The EV3 cannot differentiate between most of these sensors though, so you have to tell it which one your have or just use the generic driver.

RCX/Analog Sensors¶

RCX sensors also fall into this category, but do not work with the EV3 - at least not with the converter cable described in the NXT Hardware Developers kit. This is due to a difference in the input port pins between the EV3 and the NXT. If someone wants design a new converter cable, we could make them work.

WeDo/Analog Sensors¶

WeDo sensors are also analog sensors. They are actually electrically similar to EV3/Analog sensors (require 5V power and have ID resistor). Currently, we only support WeDo sensors attached to a WeDo hub, but if someone would like to design a cable and modify the wedo-sensor and lego-ports drivers, we could easily make them work with the input ports on the EV3.

LEGO NXT Color Sensors¶

The LEGO NXT Color Sensor is in a class of its own. It uses a hybrid of analog and (non-standard) digital communications. The NXT Color Sensor is not usable at this point in time. We can detect it with the auto-detect, but we don’t have a driver for it yet.

I2C Sensors¶

I2C sensors are sensors that communicate with the intelligent brick via the I2C protocol. In the NXT documentation, they are referred to a “digital” sensors. These sensors can be sorted into two categories.

NXT/I2C Sensors¶

These are sensors designed using LEGO’s guidelines for NXT digital sensors. NXT/I2C sensors can be automatically detected because they contain vendor and product IDs at specific I2C registers.

Other/I2C Sensors¶

These can be any off-the-shelf I2C device or 3rd party sensors that are designed for LEGO MINDSTORMS, but do not follow the guidelines of NXT/I2C sensors.

UART Sensors¶

The EV3 has a UART transceiver connected to each input port that can be used to communicate with many devices using this widely used standard.

EV3/UART Sensors¶

These is a new type of sensor that is designed specifically for the EV3 (they don’t work with the NXT). These sensors are a bit “smarter” in that in addition to sending the data of what they measure, they also send information about their capabilities. This means that any new EV3/UART sensors should “just work” without us having to write new drivers.

Other/UART Sensors¶

In addition to sensors designed to work with EV3, any UART device can be connected. But, be careful of voltage levels. The EV3 uses 3.3V I/O. It is safe to connect other devices that use 3.3V or 5V I/O. But, don’t connect anything with higher voltage!

The lego-sensor Subsytem¶

The lego-sensor class provides a uniform interface for using most of the sensors available for the EV3. The various underlying device drivers will create a lego-sensor device for interacting with the sensors.

Sensors are primarily controlled by setting the mode and monitored by reading the value<N> attributes. Values can be converted to floating point if needed by value<N> / 10.0 ^ decimals.

Identifying sensors¶

Since the name of the sensor<N> device node does not correspond to the port that a sensor is plugged in to, you must look at the address attribute if you need to know which port a sensor is plugged in to. However, if you don’t have more than one sensor of each type, you can just look for a matching driver_name. Then it will not matter which port a sensor is plugged in to - your program will still work.

Sysfs¶

Sensors can be found at /sys/class/lego-sensor/sensor<N>, where <N> is incremented each time a sensor is loaded.

Note

The number <N> is not related to the port address.

Sysfs Attributes¶
Attribute	Access	Description
`address`	read-only	Returns the name of the port that the sensor is connected to, e.g. `in1`. I2C sensors also include the I2C address (decimal), e.g. `in1:i2c8`.
`bin_data`	read-only	Reading the file will give the unscaled raw values in the `value<N>` attributes. Use `bin_data_format`, `num_values` and the individual sensor documentation to determine how to interpret the data.
`bin_data_format`	read-only	Returns the format of the values in `bin_data` for the current mode. Possible values are: `u8`: Unsigned 8-bit integer (byte) `s8`: Signed 8-bit integer (sbyte) `u16`: Unsigned 16-bit integer (ushort) `s16`: Signed 16-bit integer (short) `s16_be`: Signed 16-bit integer, big endian `s32`: Signed 32-bit integer (int) `s32_be`: Signed 32-bit integer, big endian `float`: IEEE 754 32-bit floating point (float)
`command`	write-only	Sends a command to the sensor. See the individual sensor documentation for possible commands. Sensors that do not support commands will return `-EOPNOTSUPP` when writing to this attribute.
`commands`	read-only	Returns a space separated list of the valid commands for the sensor. Returns `-EOPNOTSUPP` if no commands are supported.
`direct`	read/write	Allows direct communication with the sensor for using advanced features that are not otherwise available through the lego-sensor class. Returns `-EOPNOTSUPP` if the sensor does not support this. Currently this only works with I2C sensors. For I2C sensors, use :c:func:`seek()` to set the register to read or write from, then read or write the number of bytes required.
`decimals`	read-only	Returns the number of decimal places for the values in the `value<N>` attributes of the current mode.
`driver_name`	read-only	Returns the name of the sensor device/driver. See the list of supported sensors for a complete list of drivers.
`fw_version`	read-only	Returns the firmware version of the sensor if available. Currently only NXT/I2C sensors support this.
`mode`	read/write	Returns the current mode. Writing one of the values returned by `modes` sets the sensor to that mode. See the individual sensor documentation for a description of the modes available for each type of sensor.
`modes`	read-only	Returns a space separated list of the valid modes for the sensor.
`num_values`	read-only	Returns the number of `value<N>` attributes that will return a valid value for the current mode.
`poll_ms`	read/write	Returns the polling period of the sensor in milliseconds. Writing sets the polling period. Setting to 0 disables polling. Returns `-EOPNOTSUPP` if changing polling is not supported. Note: Setting `poll_ms` too high can cause the input port autodetection to fail. If this happens, use the `mode` attribute of the port to force the port to nxt-i2c mode. Values must not be negative.
`units`	read-only	Returns the units of the measured value for the current mode. May return empty string if units are unknown.
`value<N>`	read-only	Returns the value or values measured by the sensor. Check `num_values` to see how many values there are. Values with N >= `num_values` will return an error. The values are fixed point numbers, so check `decimals` to see if you need to divide to get the actual value.
`text_value`	read-only	Returns a space delimited string representing sensor-specific text values. Returns `-EOPNOTSUPP` if a sensor does not support text values.

Events¶

In addition to the usual add and remove events, the kernel change event is emitted when mode or poll_ms is changed. The value<N> attributes change too rapidly to be handled this way and therefore do not trigger any uevents.

Sensor Modules¶

The sensor drivers are implemented in the following modules:

EV3/Analog¶

The ev3-analog-sensor module provides all of the drivers for EV3/Analog sensors.

You can a list of the the devices implemented by this module by reading the driver_names attribute in the /sys/bus/lego/drivers/ev3-analog-sensor/.

EV3/UART¶

The ev3-uart-sensor-ld module is a tty line discipline that runs on top of a tty. It listens for the information data that is sent from EV3/UART sensors. When it receives valid data, it negotiates with the sensor, telling the sensor to enter data sending mode.

This line discipline has been assigned the number 29. To attach this line discipline to a tty, run ldattach 29 /dev/tty<N> where <N> is the name of the tty you want to connect to.

Note

This driver works with any tty, which means the sensor does not necessarily have to be plugged into one of the input ports on the EV3.

EV3/UART sensors do not require individual driver implementations like other types of sensors. Instead, all of the needed info to sent from the sensor in a common format. As a result, the name returned by the driver_name attribute may not be a real driver name. For well-known sensors (the LEGO EV3 sensors and FatcatLab sensors) it will return a name like lego-ev3-color. For unknown sensors it returns ev3-uart-<N>, where <N> is the type id of the sensor.

The ev3-uart-sensor module provides all of the drivers for EV3/UART sensors. This module is only used on devices that can’t use the line discipline.

You can a list of the the devices implemented by this module by reading the driver_names attribute in the /sys/bus/lego/drivers/ev3-uart-sensor/.

NXT/Analog¶

The nxt-analog-sensor module provides all of the drivers for NXT/Analog sensors. These drivers scale the analog voltage read from the sensor to a useful value.

You can a list of the the devices implemented by this module by reading the driver_names attribute in the /sys/bus/lego/drivers/nxt-analog-sensor/.

NXT/I2C¶

The nxt-i2c-sensor module provides all of the drivers for NXT/I2C sensors.

Module Parameters¶
`allow_autodetect`	Setting to `N` disables probing of sensors. Default is `Y`.
`default_poll_ms`	This provides the default value for the `poll_ms` attribute. A value of 0 will disable polling by default. Changes only affect sensors plugged in after the change was made. Default is 100 msec. Values must not be negative.

Note

These parameters can be changed at runtime by writing to /sys/module/nxt_i2c_sensor/parameters/<parameter>.

You can a list of the the devices implemented by this module by reading the driver_names attribute in the /sys/bus/lego/drivers/nxt-i2c-sensor/.

Motors / Output Devices¶

The EV3 has four output ports for connecting motors and other devices (like LEDs). If you are trying to use something that plugs into one of the output ports, then you are in the right place. If you are working with a motor that connects to a motor controller which plugs into an input port, you will find information on the motor controller on the [sensors] page.

This page lists well-known devices, however any device that is rated for 9VDC, requires 500mA or less and can handle pulse width modulation is safe to connect directly to the output ports on the EV3.

Supported Motors¶

Part Number	Name	Driver	Type	Auto-detect
Actuonix
L12-EV3-100	L12 EV3 100mm	`act-l12-ev3-100`	ev3	N [1]
L12-EV3-50	L12 EV3 50mm	`act-l12-ev3-50`	ev3	N [1]
LEGO
43362	Motor 9V Mini-motor, newer lighter weight	`lego-43362`	rcx	N
45502	EV3 Large Servo Motor	`lego-ev3-l-motor`	ev3	Y [1]
45503	EV3 Medium Servo Motor	`lego-ev3-m-motor`	ev3	Y [1]
47154	Technic Motor 9V Geared	`lego-47154`	rcx	N
70823	Motor 9V Micromotor	`lego-70823`	rcx	N
71427	Motor 9V Mini-motor, older heavier weight	`lego-71427`	rcx	N
74569	Technic Motor 9V	`lego-74569`	rcx	N
88002	Power Functions Train Motor	`lego-88002`	rcx	N
88003	Power Functions L-Motor	`lego-88003`	rcx	N
88004	Power Functions Servo Motor	`lego-88004`	rcx	N
8882	Power Functions XL-Motor	`lego-8882`	rcx	N
8883	Power Functions M-Motor	`lego-8883`	rcx	N
9670	Power Functions E-Motor	`lego-9670`	rcx	N
9842	NXT (Interactive Servo) Motor	`lego-nxt-motor`	ev3	Y [1]

[1]	(1, 2, 3, 4, 5) Motors are only automatically detected on the LEGO MINDSTORMS EV3 platform. LEGO NXT Motors are detected as LEGO EV3 Large motors. 3rd party motors will not be correctly detected and must be manually specified.

Types of Motors¶

There are currently three basic types of classes of devices that are supported in ev3dev. Tacho motors, DC motors and LEDs.

Tacho Motors¶

Tacho motors get their name from the LMS2012 (official LEGO) source code. Tacho is short for tachometer. This is probably a bit of a misnomer because the motor itself does not have a tachometer. Instead, the EV3 brick acts as the tachometer. Technically speaking the motors have a incremental rotary encoder (also called quadrature encoder) that is used by the EV3 to determine the speed and direction of rotation.

DC Motors¶

DC motors are just “plain” motors. They do not have a quadrature encoder for feedback.

LEDs¶

Any 9VDC rated (i.e. it has an appropriately sized resistor) LED can be used.

Using Motors and LEDs¶

Currently, only NXT and EV3 motors can be automatically detected. To use other devices, see the [EV3 Output Port Driver] for information on how to set the mode of the output port.

RCX compatible (aka 9V) motors and LEDs can be connected to the EV3 using a LEGO 8528 cable.

Power Functions motors and LEDs can be connected using a LEGO 8528 cable plus a LEGO 8886 cable or LEGO 8871 cable.

tacho-motor Subsystem¶

The tacho-motor class provides a uniform interface for using motors with positional and directional feedback such as the EV3 and NXT motors. This feedback allows for precise control of the motors.

Sysfs¶

Tacho motors can be found at /sys/class/tacho-motor/motor<N>, where <N> is incremented each time a motor is loaded.

Note

The number <N> is not related to the port the motor is plugged in to.

sysfs attributes¶
Attribute	Access	Description
`address`	read-only	Returns the name of the port that the motor is connected to.
`command`	write-only	Sends a command to the motor controller. Possible values are: `run-forever`: Causes the motor to run until another command is sent. `run-to-abs-pos`: Runs the motor to an absolute position specified by``position_sp`` and then stops the motor using the command specified in `stop_action`. `run-to-rel-pos`: Runs the motor to a position relative to the current position value. The new position will be current `position` + `position_sp`. When the new position is reached, the motor will stop using the command specified by `stop_action`. `run-timed`: Run the motor for the amount of time specified in `time_sp` and then stops the motor using the command specified by `stop_action`. `run-direct`: Runs the motor using the duty cycle specified by `duty_cycle_sp`. Unlike other run commands, changing `duty_cycle_sp` while running will take effect immediately. `stop`: Stop any of the run commands before they are complete using the command specified by `stop_action`. `reset`: Resets all of the motor parameter attributes to their default values. This will also have the effect of stopping the motor. Not all commands may be supported. Read the `commands` attribute to get the list of commands supported by a particular driver.
`commands`	read-only	Returns a space separated list of commands that are supported by the motor controller.
`count_per_rot`	read-only	Returns the number of tacho counts in one rotation of the motor. Tacho counts are used by the position and speed attributes, so you can use this value to convert from rotations or degrees to tacho counts. (rotation motors only)
`count_per_m`	read-only	Returns the number of tacho counts in one meter of travel of the motor. Tacho counts are used by the position and speed attributes, so you can use this value to convert from distance to tacho counts. (linear motors only)
`full_travel_count`	read-only	Returns the number of tacho counts in the full travel of the motor. When combined with the count_per_m atribute, you can use this value to calculate the maximum travel distance of the motor. (linear motors only)
`driver_name`	read-only	Returns the name of the driver that provides this tacho motor device.
`duty_cycle`	read-only	Returns the current duty cycle of the motor. Units are percent. Values are -100 to 100.
`duty_cycle_sp`	read/write	Writing sets the duty cycle setpoint. Reading returns the current value. Units are in percent. Valid values are -100 to 100. A negative value causes the motor to rotate in reverse.
`polarity`	read/write	Sets the polarity of the motor. Valid values are: `normal`: A positive duty cycle will cause the motor to rotate clockwise. `inversed`: A positive duty cycle will cause the motor to rotate counter-clockwise.
`position`	read/write	Returns the current position of the motor in pulses of the rotary encoder. When the motor rotates clockwise, the position will increase. Likewise, rotating counter-clockwise causes the position to decrease. Writing will set the position to that value. The range is -2,147,483,648 and +2,147,483,647 tachometer counts (32-bit signed integer).
`hold_pid/Kd`	read/write	The derivative constant for the position PID.
`hold_pid/Ki`	read/write	The integral constant for the position PID.
`hold_pid/Kp`	read/write	The proportional constant for the position PID.
`max_speed`	read	Returns the maximum value that is accepted by the `speed_sp` attribute. This value is the speed of the motor at 9V with no load. Note: The actual maximum obtainable speed will be less than this and will depend on battery voltage and mechanical load on the motor.
`position_sp`	read/write	Writing specifies the target position for the `run-to-abs-pos` and `run-to-rel-pos` commands. Reading returns the current value. Units are in tacho counts. You can use the value returned by `counts_per_rot` to convert tacho counts to/from rotations or degrees. The range is -2,147,483,648 and +2,147,483,647 tachometer counts (32-bit signed integer).
`speed`	read-only	Returns the current motor speed in tacho counts per second. Note, this is not necessarily degrees (although it is for LEGO motors). Use the `count_per_rot` attribute to convert this value to RPM or deg/sec.
`speed_sp`	read/write	Writing sets the target speed in tacho counts per second used for all `run-` commands except `run-direct`. Reading returns the current value. A negative value causes the motor to rotate in reverse with the exception of `run-to--pos` commands where the sign is ignored. Use the `count_per_rot` attribute to convert RPM or deg/sec to tacho counts per second. Use the `count_per_m` attribute to convert m/s to tacho counts per second.
`ramp_up_sp`	read/write	Writing sets the ramp up setpoint. Reading returns the current value. Units are in milliseconds and must be positive. When set to a non-zero value, the motor speed will increase from 0 to 100% of `max_speed` over the span of this setpoint. The actual ramp time is the ratio of the difference between the `speed_sp` and the current `speed` and max_speed multiplied by `ramp_up_sp`. Values must not be negative.
`ramp_down_sp`	read/write	Writing sets the ramp down setpoint. Reading returns the current value. Units are in milliseconds and must be positive. When set to a non-zero value, the motor speed will decrease from 0 to 100% of `max_speed` over the span of this setpoint. The actual ramp time is the ratio of the difference between the `speed_sp` and the current `speed` and `max_speed` multiplied by `ramp_down_sp`. Values must not be negative.
`speed_pid/Kd`	read/write	The derivative constant for the speed regulation PID.
`speed_pid/Ki`	read/write	The integral constant for the speed regulation PID.
`speed_pid/Kp`	read/write	The proportional constant for the speed regulation PID.
`state`	read-only	Reading returns a space separated list of state flags. Possible flags are: `running`: Power is being sent to the motor. `ramping`: The motor is ramping up or down and has not yet reached a constant output level. `holding`: The motor is not turning, but rather attempting to hold a fixed position. `overloaded`: The motor is turning as fast as possible, but cannot reach its `speed_sp`. `stalled`: The motor is trying to run but is not turning at all.
`stop_action`	read/write	Reading returns the current stop action. Writing sets the stop action. The value determines the motors behavior when `command` is set to `stop`. Possible values are: `coast`: Removes power from the motor. The motor will freely coast to a stop. `brake`: Removes power from the motor and creates a passive electrical load. This is usually done by shorting the motor terminals together. This load will absorb the energy from the rotation of the motors and cause the motor to stop more quickly than coasting. `hold`: Causes the motor to actively try to hold the current position. If an external force tries to turn the motor, the motor will “push back” to maintain its position. Not all actions may be supported. Read `stop_actions` to get the actions available for a particular driver.
`stop_actions`	read-only	Returns a space-separated list of stop actions supported by the motor controller.
`time_sp`	read/write	Writing specifies the amount of time the motor will run when using the `run-timed` command. Reading returns the current value. Units are in milliseconds. Values must not be negative.

dc-motor Subsystem¶

The dc-motor class provides a uniform interface for using regular DC motors with no fancy controls or feedback. This includes LEGO MINDSTORMS RCX motors and LEGO Power Functions motors.

Sysfs¶

DC motors can be found at /sys/class/dc-motor/motor<N>, where <N> is incremented each time a motor is loaded.

Note

The number <N> is not related to the port address.

Sysfs Attributes¶
Attribute	Access	Description
`address`	read-only	Returns the name of the port that the motor is connected to.
`command`	write-only	Sets the command for the motor. Possible values are: `run-forever`: Causes the motor to run until another command is sent. `run-timed`: Runs the motor for the amount of time specified in `time_sp` and then stops the motor using the command specified by `stop_action`. `run-direct`: Runs the motor at the duty cycle specified by `duty_cycle_sp`. Unlike other run commands, changing `duty_cycle_sp` while running will take effect immediately. `stop`: Stops any of the run commands before they are complete using the command specified by `stop_action`. Not all commands may be supported. Read `commands` to find out which commands are supported for a particular driver.
`commands`	read-only	Returns a space separated list of commands supported by the motor controller.
`driver_name`	read-only	Returns the name of the motor driver that loaded this device. See the list of supported motors for a list of drivers.
`duty_cycle`	read-only	Shows the current duty cycle of the PWM signal sent to the motor. Values are -100 to 100 (-100% to 100%).
`duty_cycle_sp`	read/write	Writing sets the duty cycle setpoint of the PWM signal sent to the motor. Valid values are -100 to 100 (-100% to 100%). Reading returns the current setpoint.
`polarity`	read/write	Sets the polarity of the motor. Valid values are: `normal`: Causes the motor to turn in the direction indicated by the sign (+/-) of the `duty_cycle_sp`. `inversed`: Causes the motor to turn in the opposite direction of the sign (+/-) of the `duty_cycle_sp`.
`state`	read-only	Gets a space separated list of flags indicating the motor status. Possible flags are: `running`: Indicates that the motor is powered. `ramping`: Indicates that the motor has not yet reached the `duty_cycle_sp`.
`stop_action`	write-only	Sets the stop action that will be used when the motor stops. Possible values are: coast: Causes the motor to coast to a stop by floating the outputs. brake: Causes the motor to stop more quickly by shorting the outputs. Not all values may be supported. Read stop_actions to find out which actions are supported for a particular driver.
`stop_actions`	read-only	Gets a space separated list of supported stop actions.
`ramp_down_sp`	read/write	Sets the time in milliseconds that it take the motor to ramp down from 100% to 0%. Valid values are 0 to 10000 (10 seconds). Default is 0.
`ramp_up_sp`	read/write	Sets the time in milliseconds that it take the motor to up ramp from 0% to 100%. Valid values are 0 to 10000 (10 seconds). Default is 0.
`time_sp`	read/write	Sets the time setpoint used with the `run-timed` command. Units are in milliseconds. Values must not be negative.

servo-motor Subsystem¶

The servo-motor class provides a uniform interface for using hobby type servo motors.

Note

LEGO calls the NXT and EV3 motors, “servo” motors on their website. Technically, that is a correct name for them because they provide position feedback. However, the servo-motor class is only used for a very specific type of servo motor that uses a 50MHz control signal.

It is not used by any LEGO brand motors.

Sysfs¶

Servo motors can be found at /sys/class/servo-motor/motor<N>, where <N> is incremented each time a servo is loaded.

Note

The number <N> is not related to the port the motor is plugged in to.

sysfs attributes¶
Attribute	Access	Description
`address`	read-only	Returns the name of the port that the motor is connected to.
`command`	write-only	Sets the command for the servo. Possible values are: `run`: Causes the servo to be driven to the position set in the `position_sp` attribute. `float`: Removes power from the motor.
`driver_name`	read-only	Returns the name of the motor driver that loaded this device.
`max_pulse_sp`	read/write	Used to set the pulse size in milliseconds for the signal that tells the servo to drive to the maximum (clockwise) `position_sp`. Default value is 2400. Valid values are 2300 to 2700. You must write to the `position_sp` attribute for changes to this attribute to take effect. Values must not be negative.
`mid_pulse_sp`	read/write	Used to set the pulse size in milliseconds for the signal that tells the servo to drive to the mid position_sp. Default value is 1500. Valid values are 1300 to 1700. For example, on a 180 degree servo, this would be 90 degrees. On continuous rotation servo, this is the “neutral” position where the motor does not turn. You must write to the `position_sp` attribute for changes to this attribute to take effect. Values must not be negative.
`min_pulse_sp`	read/write	Used to set the pulse size in milliseconds for the signal that tells the servo to drive to the minimum (counter-clockwise) position. Default value is 600. Valid values are 300 to 700. You must write to the `position_sp` attribute for changes to this attribute to take effect. Values must not be negative.
`polarity`	read/write	Sets the polarity of the servo. Valid values are: `normal`: Causes the `position_sp` attribute to act in the usual manner. `inversed`: Causes the `position_sp` value to be inverted. i.e `-100` will correspond to `max_pulse_sp`, and `100` will correspond to `min_pulse_sp`.
`position_sp`	read/write	Reading returns the current `position_sp` of the servo. Writing instructs the servo to move to the specified position_sp. Units are percent. Valid values are -100 to 100 (-100% to 100%) where `-100` corresponds to `min_pulse_sp`, `0` corresponds to `mid_pulse_sp` and `100` corresponds to `max_pulse_sp`.
`rate_sp`	read/write	Sets the rate_sp at which the servo travels from 0 to 100.0% (half of the full range of the servo). Units are in milliseconds. Example: Setting `rate_sp` to 1000 means that it will take a 180 degree servo 2 seconds to move from 0 to 180 degrees. Note: Some servo controllers may not support this in which case reading and writing will fail with `-EOPNOTSUPP`. In continuous rotation servos, this value will affect the rate at which the speed ramps up or down. Values must not be negative.
`state`	read-only	Returns a space separated list of flags indicating the state of the servo. Possible flag is: `running`: Indicates that the motor is powered.

Motor Modules¶

EV3/EVB Motors¶

The legoev3-motor module is used on devices like the EV3 where motors are connected directly to the CPU rather than an external controller.

Generic DC Motors¶

The rcx-motor module provides a dc-motor Subsystem interface for RCX motors, Power Functions motors or any other 9V rated DC motor connected to an output port. You can find the devices bound to this driver in the directory /sys/bus/lego/drivers/rcx-motor.

Generic LEDs¶

The rcx-led module provides a leds interface for RCX motors, Power Functions motors or any other 9V rated LED connected to an output port.

Input / Output Ports¶

This page is about the kind of ports that you plug sensors and motors into. Ports that have more than one connection type will have drivers that let you control the port itself. The input and output ports on the EV3 itself and some sensor multiplexers fall into this category (see list below). Simple multiplexers that only support one connection type will not have a separate driver for the port.

Input Port 5 on the BrickPi is physically wired to the I2C pins on the RaspberryPi. See BrickPi Input Port 5 for the details.

Port drivers use the lego-port-class to provide a common interface for interacting with individual ports. Follow the link for more information.

List of port drivers¶

This is a list of port drivers that are currently available in the ev3dev kernel.

Name	Description	Connection Types	Module
`brickpi-out-port`	Dexter Industries BrickPi Output Port	tacho-motor, dc-motor, led	`brickpi`
`ms-ev3-smux-port`	mindsensors.com EV3 Sensor Multiplexer Input Port	EV3/UART, EV3/Analog	`ms-ev3-smux`
`pistorms-out-port`	mindsensors.com PiStorms Output Port	tacho-motor	`pistorms`
`brickpi3-in-port`	Dexter Industries BrickPi3 Input Port	NXT/Analog, NXT/I2C, EV3/Analog, EV3/UART	`brickpi3`
`legoev3-output-port`	EV3 Output Port	tacho-motor, dc-motor, led	`legoev3_ports`
`brickpi3-out-port`	Dexter Industries BrickPi3 Output Port	tacho-motor, dc-motor, led	`brickpi3`
`brickpi-in-port`	Dexter Industries BrickPi Input Port	NXT/Analog, NXT/I2C, EV3/Analog, EV3/UART	`brickpi`
`pistorms-in-port`	mindsensors.com PiStorms Input Port	NXT/Analog, NXT/Color, NXT/I2C, Other/I2C, EV3/Analog, EV3/UART	`pistorms`
`evb-output-port`	EV3 Output Port	tacho-motor, dc-motor, led	`evb_ports`
`ht-nxt-smux-port`	HiTechnic NXT Sensor Multiplexer Input Port	NXT/I2C, NXT/Analog	`ht-nxt-smux`
`legoev3-input-port`	EV3 Input Port	NXT/Analog, NXT/I2C, Other/I2C, EV3/Analog, EV3/UART, Other/UART	`legoev3_ports`
`wedo-port`	LEGO WeDo Port	WeDo/Analog, dc-motor, led	`wedo`
`ms-nxtmmx-out-port`	mindsensors.com NXTMMX Output Port	tacho-motor	`ms-nxtmmx`
`evb-input-port`	EV3 Input Port	NXT/Analog, NXT/I2C, Other/I2C, EV3/Analog, EV3/UART, Other/UART	`evb_ports`

The lego-port Subsystem¶

The lego-port class provides an interface for working with input and output ports that are compatible with LEGO MINDSTORMS RCX/NXT/EV3, LEGO WeDo and LEGO Power Functions sensors and motors. Supported devices include the LEGO MINDSTORMS EV3 Intelligent Brick, the LEGO WeDo USB hub and various sensor multiplexers from 3rd party manufacturers.

Some types of ports may have multiple modes of operation. For example, the input ports on the EV3 brick can communicate with sensors using UART, I2C or analog validate signals - but not all at the same time. Therefore there are multiple modes available to connect to the different types of sensors.

In most cases, ports are able to automatically detect what type of sensor or motor is connected. In some cases though, this must be manually specified using the mode and set_device attributes. The mode attribute affects how the port communicates with the connected device. For example the input ports on the EV3 brick can communicate using UART, I2C or analog but not all at the same time, so the mode must be set to the one that is voltages, appropriate for the connected sensor. The set_device attribute is used to specify the exact type of sensor that is connected. Note: the mode must be correctly set before setting the sensor type.

Sysfs¶

Ports can be found at /sys/class/lego-port/port<N> where <N> is incremented each time a new port is registered.

Note

The number <N> is not related to the actual port at all - use the address attribute to find a specific port.

Sysfs Attributes¶
Attribute	Access	Description
`address`	read-only	Returns the name of the port. See individual driver documentation for the name that will be returned.
`driver_name`	read-only	Returns the name of the driver that loaded this device. You can find the complete list of drivers in the list of port drivers.
`modes`	read-only	Returns a space separated list of the available modes of the port.
`mode`	read/write	Reading returns the currently selected mode. Writing sets the mode. Generally speaking when the mode changes any sensor or motor devices associated with the port will be removed new ones loaded, however this will depend on the individual driver implementing this class.
`set_device`	write-only	For modes that support it, writing the name of a driver will cause a new device to be registered for that driver and attached to this port. For example, since the exact type of an NXT/Analog sensor cannot be automatically detected, you must use this attribute to load the correct driver. For I2C sensors, you must write the I2C address in addition to the driver name. Returns `-EOPNOTSUPP` if setting a device is not supported for the current `mode` of the port.
`status`	read-only	In most cases, reading status will return the same value as `mode`. In cases where there is an `auto` mode additional values may be returned, such as `no-device` or `error`. See individual port driver documentation for the full list of possible values.

Events¶

In addition to the usual add and remove events, the kernel change event is emitted when mode or status changes.

Port Multiplexers¶

Port multiplexers are used to connect more than one sensor or motor to a single input or output port. Some multiplexers are treated as a single sensor while others have their own port drivers.

Supported Multiplexers¶

Part Number	Name	Ports	Supported connections
HiTechnic
NTX1060	NXT Touch Sensor Multiplexer	4	LEGO NXT Touch sensor
NSX2020	HiTechnic Sensor Multiplexer	4	NXT/Analog and NXT/I2C sensors
mindsensors.com
EV3SensorMux	EV3 Sensor Multiplexer for EV3 or NXT	3	LEGO EV3 sensors (no 3rd party sensors)
NXTMMX-v2	Multiplexer for NXT/EV3 Motors	3	LEGO EV3/NXT motors
NXTServo-v3	8 Channel Servo Controller for NXT or EV3	8	Hobby type RC servo motors
NXTTouchMux	Touch Sensor Multiplexer for NXT	3	LEGO NXT Touch sensors
SPLIT-Nx-v2	Port Splitter for NXT Digital Sensors	3	All I2C sensors

HiTechnic¶

NXT Touch Sensor Multiplexer¶

This multiplexer allows connecting up to 4 LEGO NXT Touch sensors to a single input port. This device is treated as a single sensor, so there are is no lego-port driver loaded.

HiTechnic Sensor Multiplexer¶

The sensor multiplexer provides 4 sensor ports via one input port. A port device is registered for each port. These can be found in /sys/class/lego-port/.

Any type of NXT/Analog sensor can be used with this multiplexer. Most NXT/I2C sensors can be uses as well, but they can only be operated as read-only.

This device cannot detect when motors are attached or removed. However, there is a command that can be used to attempt to detect sensors after they have been attached. This only works for certain LEGO and HiTechnic NXT sensors.

General Info¶

Module	`ht-nxt-smux`
Driver name	`ht-nxt-smux-port`
Connection types	NXT/I2C, NXT/Analog
Connection prefix	`mux` [1]
Number of modes	2

Modes¶

Name	Description
`analog` [2]	NXT/Analog sensor
`i2c` [3]	NXT/I2C sensor

Notes¶

[1]	The full `address` is in the format: `<parent-address>:]mux<n>`. For example, if we are looking at port 1 of this mux plugged into input port 2 on the EV3, the address will be `in2:i2c08:mux1`.

[2]	The generic `nxt-analog` driver will be loaded when this mode is set. You must manually specify the correct driver for your sensor using `set_device` if you want to use another driver. Any driver with a connection type of NXT/Analog is allowed.

[3] If one of the supported sensors was detected by invoking the DETECT command on the HiTechnic NXT Sensor Multiplexer associated with this port, then the appropriate driver will be automatically loaded. Otherwise, you can use set_device to load the correct driver for your sensor. Most drivers with a connection type of NXT/I2C are allowed.

A ht-smux-i2c-sensor device is loaded by the HiTechnic NXT Sensor Multiplexer driver when it is detected by the sensor mux (automatic detection only works with the sensors listed in the linked page) or when manually specified by setting the port to i2c mode and writing the device name to set_device. You can use any one of the sensors that has the nxt-i2c-sensor module from the Supported Sensors. Keep in mind though that the sensor mux operates in a read-only mode with I2C sensors. You will not be able to use commands with these sensors. Additionally, some modes of I2C sensors require writing data to the sensor and as a result, these modes will not be usable either.

Mindsensors.com¶

EV3 Sensor Multiplexer for EV3 or NXT¶

This multiplexer allows connecting three EV3 sensors to a single input port. Only LEGO brand EV3 sensors are supported - 3rd party EV3 sensors won’t work.

General Info¶

Module	`ms-ev3-smux`
Driver name	`ms-ev3-smux-port`
Connection types	EV3/UART, EV3/Analog
Connection prefix	`mux` [4]
Number of modes	2

Modes¶

Name	Description
`uart` [5]	EV3/UART sensor
`analog` [6]	EV3/Analog sensor

Notes¶

[4]	The full `address` is in the format: `[<parent-address>:]mux<n> For example, if we are looking at port 1 of this mux plugged into input port 2 on the EV3, the address will be `in2:i2c50:mux1`.

[5]

UART sensor types are not automatically detected. By default, the lego-ev3-color driver will be loaded when this mode is set. Use set_device to load other sensor devices/drivers.

Supported sensors are:

Sensor Name	Device/Driver Name
LEGO EV3 Color	`lego-ev3-color`
LEGO EV3 Ultrasonic	`lego-ev3-us`
LEGO EV3 GYRO	`lego-ev3-gyro`
LEGO EV3 Infrared	`lego-ev3-ir`

[6]	Currently only the LEGO EV3 Touch sensor is supported. The `lego-ev3-touch` driver is loaded when this mode is set.

Multiplexer for NXT/EV3 Motors¶

The NXT motor multiplexer provides 3 motor ports via one input port. A port device is registered for each port. These can be found in /sys/class/lego-port/. This device cannot detect when motors are attached or removed.

General Info¶

Module	`ms-nxtmmx`
Driver name	`ms-nxtmmx-out-port`
Connection types	tacho-motor
Connection prefix	`M` [7]
Number of modes	1

Modes¶

Name	Description
`tacho-motor`	NXT/EV3 Large Motor

Notes¶

[7]	The full address will be something like `in2:i2c3:M1` depending on what port the motor multiplexer is plugged into.

8 Channel Servo Controller for NXT or EV3¶

This multiplexer allows connecting up to 8 hobby type RC servo motors to a single input port. There is no port device associated with this. When connected, It loads 8 servo-motor Subsystem devices that are used to control the motors.

Touch Sensor Multiplexer for NXT¶

This multiplexer allows connecting up to 3 LEGO NXT Touch sensors to a single input port. This device is treated as a single sensor, so there are is no lego-port driver loaded.

Port Splitter for NXT Digital Sensors¶

This multiplexer allows connecting up to 3 I2C sensors to a single input port. This is a passive device, so there are no drivers. All connected I2C devices must have a unique I2C address.

LEGO MINDSTORMS EV3¶

Input / Output Ports¶

By default, a sysfs device is created for each input and output port on the EV3. See the input ports and output ports driver descriptions for more information on how these work. There is a single module for input and output ports named legoev3_ports. This module has some module parameters.

Module Parameters¶
Name	Description
`disable_in_port`	Used to prevent the input port device from being loaded. This is useful if you want to use input port 1 for printing kernel messages this if you want while you are debugging the Linux kernel. You may also want to do to control the input port gpios directly.
`disable_out_port`	Used to prevent the output port from being loaded. This leaves the pwm device and gpios used by the port free to be controlled directly or used by other drivers.

Input Ports¶

LEGO MINDSTORMS EV3 has four input ports labeled 1, 2, 3 and 4. These ports are used with LEGO MINDSTORMS EV3 and NXT compatible sensors and other devices. Most sensors can be automatically detected when plugged in.

General Info¶

Module	`legoev3_ports`
Driver name	`legoev3-input-port`
Connection types	NXT/Analog, NXT/I2C, Other/I2C, EV3/Analog, EV3/UART, Other/UART
Connection prefix	`in`
Number of modes	9

Modes¶

Name	Description
`auto` [1]	Automatically detect sensors.
`nxt-analog` [2]	Configure the port for NXT/Analog sensors
`nxt-color` [3]	Configure the port for the LEGO NXT Color sensor
`nxt-i2c`	Configure for I2C communications and load the `nxt-i2c-host` device.
`other-i2c`	Configure for I2C communications but do not probe for NXT sensors.
`ev3-analog`	Configure the port for EV3/Analog sensors
`ev3-uart`	Configure for UART communications and load the `ev3-uart-host` device.
`other-uart`	Configure for UART communications but do not load any device.
`raw` [4]	Provide access to low level drivers.

Notes¶

[1]	In auto mode, the port will attempt to automatically detect the type of sensor that was connected and load the appropriate driver. See the list of Supported Sensors to determine if a sensor can be automatically detected.

[2]	This loads the generic NXT/Analog Sensors driver by default. Use `set_device` to load the appropriate device/driver.

[3]	NXT Color sensor driver has not been implemented yet, so right now, this mode does nothing.

[4]	Exports gpios and analog/digital converter values to sysfs so that they can be controlled directly.

Output Ports¶

LEGO MINDSTORMS EV3 has four output ports labeled A, B, C and D. These ports are used with LEGO MINDSTORMS EV3, NXT and RCX compatible motors and other devices. EV3 motors can be automatically detected when plugged in. Other motors with position feedback (such as the NXT motor) are usually detected as an EV3 Large Motor. RCX motors and LEDs cannot be automatically detected and the mode of the output port must be manually set to use these types of devices.

General Info¶

Module	`legoev3_ports`
Driver name	`legoev3-output-port`
Connection types	tacho-motor, dc-motor, led
Connection prefix	`out`
Number of modes	5

Modes¶

Name	Description
`auto` [5]	Automatically detect motors when they are connected.
`tacho-motor` [6]	Load the [tacho-motor] device.
`dc-motor` [7]	Load the dc-motor Subsystem device.
`led` [8]	Load the LEDs device.
`raw` [9]	Provide access to low level drivers.

Notes¶

[5]	Only the EV3/NXT large motors and the EV3 medium motor can be automatically detected. All other devices must be manually configured.

[6]	Configures the port to use the tacho-motor Subsystem driver module. The default driver is the EV3 Large Motor (`lego-ev3-l-motor`). You can change the driver using the `set_device` attribute.

[7]	This can be use with MINDSTORMS RCX motors, Power Functions motors and any other “plain” DC motor. By “plain”, we mean the motor is just a motor without any feedback.

[8]	This can be used with MINDSTORMS RCX LEDs, Power Functions LEDs or any other LED connected to pins 1 and 2 of the output port.

[9]	Exports gpios, pwm and analog/digital converter values to sysfs so that they can be controlled directly.

Buttons¶

The EV3 buttons use the standard Linux input subsystem. You can find the event device node at /dev/input/by-path/platform-gpio-keys.0-event. The buttons are mapped to Linux key codes as shown in the table below.

Button map¶
Button	Linux key code (value)
Back	`KEY_BACKSPACE` (14)
Center	`KEY_ENTER` (28)
Up	`KEY_UP` (103)
Left	`KEY_ENTER` (105)
Right	`KEY_ENTER` (106)
Down	`KEY_DOWN` (108)

LEDs¶

The EV3 brick status LEDs used the standard Linux LEDs subsystem. You can find the LED devices at /sys/class/leds/. There are two bi-color LEDs. The color for each LED is controlled separately, so there is a green and red device node for each LED. Turning both of these on at the same time will make the LED appear orange(ish).

The LEDs are controlled by a PWM signal, so you can vary the brightness between 0 and max_brightness.

Display¶

The EV3 display uses the standard Linux frame buffer subsystem (fbdev). The display memory can be directly accessed by reading and writing or memory mapping /dev/fb0. Display attributes such as width, height and row stride can be read using FBIOGET_VSCREENINFO and FBIOGET_FSCREENINFO ioctls.

Note

You must make sure that you control the active virtual console before drawing on the display, otherwise other programs could be writing to the display at the same time, causing unexpected results.

Sound¶

The snd-legoev3 module provedes an ALSA driver for PCM playback and a Linux input device with sound capabilities (EV_SND) for producing tones.

The ALSA driver can be used with standard tools such as alsamixer and aplay. Tones can be produced by using the beep command, ioctls such as KDMKTONE (must run on local console or as root for ioctls) or by writing SND_* events to the event device (must be member of input group for this).

Battery¶

This driver is used to get information about the EV3 battery.
It uses the power_supply subsystem.
It registers a sysfs device node at /sys/class/power_supply/lego-ev3-battery/.

Sysfs Attributes¶
`current_now`	Returns the battery current in microamps.
`scope`	Always returns `System`.
`technology`	Returns `Unknown` or `Li-ion` depending on if the rechargeable battery is present. If the technology is `Unknown`, you can write `NiMH` to this attribute if you are using rechargeable NiMH batteries.
`type`	Always returns `Battery`.
`voltage_max_design`	Returns the nominal “full” battery voltage. The value returned depends on `technology`.
`voltage_min_design`	Returns the nominal “empty” battery voltage. The value returned depends on `technology`.
`voltage_now`	Returns the battery voltage in microvolts.

LEGO WeDo¶

I/O Ports¶

The WeDo USB hub has 2 I/O ports. These can be connected to WeDo sensors or Power Functions Motors.

Note

The hub can only provide 5V to motors, so they will not be as powerful as if you were using a proper Power Functions battery. You also need to be careful not to overload your USB port. Most ports are limited to 500mA per the USB specification. However, the EV3 will supply up to 1A.

General Info¶

Module	`wedo`
Driver name	`wedo-port`
Connection types	WeDo/Analog, dc-motor, led
Connection prefix	`wedo` [1]
Number of modes	1

Modes¶

Name	Description
`auto`	The attached device is automatically detected.

Notes¶

[1]

The full address is in the format:

usb<usb-path>:wedo<n>

The USB path might be something like 1-1.3:1.0. Read more about it here. Run lsusb -t to help figure out the correct path for your WeDo hub.

For example, this:

/:  Bus 05.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/4p, 480M
    |__ Port 4: Dev 5, If 0, Class=Hub, Driver=hub/4p, 480M
        |__ Port 2: Dev 6, If 0, Class=Human Interface Device, Driver=wedo, 1.5M

...translates to usb5-4.2:1.0:wedo1. You can see how Bus 05, Port 4 and Port 2 result in 5-4.2. The last bit (configuration and interface) will always be :1.0.

Dexter Industries BrickPi/BrickPi+¶

This page describes the drivers that are specific to Dexter Industries BrickPi and BrickPi+ These controllers are LEGO MINDSTORMS compatible addon boards for Raspberry Pi.

Note

BrickPi is identified by hardware v1.7.3 and BrickPi+ is identified as v2.8.

Input Ports¶

The BrickPi and BrickPi+ have 4 input ports that can be used with LEGO MINDSTORMS compatible sensors. It works with most sensors, but there are some exceptions. It only supports the LEGO brand EV3/UART Sensors and EV3/Analog Sensors. Also, there are currently some limitations on the supported NXT/I2C Sensors (See the I2C Sensor Driver). Any type of NXT/Analog Sensors will work.

Note

Unlike the EV3, BrickPi cannot automatically detect sensors! You must manually specify the type of sensor that is attached to the port using the mode and set_device attributes.

General Info¶

Module	`brickpi`
Driver name	`brickpi-in-port`
Connection types	NXT/Analog, NXT/I2C, EV3/Analog, EV3/UART
Connection prefix	``S`` [1]
Number of modes	6

Modes¶

Name	Description
`none`	No sensor
`nxt-analog` [2]	NXT/Analog sensor
`nxt-color`	LEGO NXT Color sensor
`nxt-i2c` [3]	NXT/I2C sensor
`ev3-analog` [4]	EV3/Analog sensor
`ev3-uart` [5]	EV3/UART sensor

Notes¶

[1]	The full port name includes the parent device node. So, the `address` attribute will return something like `ttyAMA0:S1`.

[2]	The `nxt-analog` driver will be loaded when this mode is set. You must manually specify the correct driver for your sensor using `set_device` if you want to use another driver. Any driver with a connection type of NXT/Analog is allowed.

[3]

No sensors are loaded by default. You must address manually specify the sensor that is connected and its by using the set_device attribute. This is equivalent to manually loading I2C devices. The sensor port address will be the BrickPi port address with ”:i2c” and the decimal I2C address appended. The I2C Sensor Driver section has information regarding the use of sensors connected to a brickpi-in-port.

[4]	Only the LEGO EV3 Touch sensor is supported.The driver will load by default.

[5]	Only the LEGO EV3 Ultrasonic, Color, Gyro, and Infrared sensors are supported. They cannot be automatically detected, so you must specify the sensor manually using the `set_device` attribute. No sensors are loaded by default.

Input Port 5¶

Note

Only the original BrickPi has an Input Port 5. BrickPi+ does not.

Input Port 5 on the BrickPi is physically wired to the I2C pins on the Raspberry Pi and I2C is supported by the i2c_bcm2708 kernel module (there is no ev3dev-specific driver for this port).

Only NXT/I2C Sensors and Other/I2C Sensors work on port 5.

Tip

Sensor types are listed in the Supported Sensors table.

Configuration¶

For Input Port 5 to work with most LEGO compatible sensors, you have to make sure that correct baudrate for the sensor is set and load the driver manually. NXT/I2C Sensors should work with the slow 9600 baudrate used originally by LEGO MINDSTORMS NXT.

You can temporarily change the baudrate on a running system. This change will be reset after a reboot:

sudo modprobe -r i2c_bcm2708 # remove module
sudo modprobe i2c_bcm2708 baudrate=9600 # load module specifying baudrate

Note

Some devices behave erratically if baudrate is changed while they are plugged in. If needed unplug your sensor, change the baudrate and plug the sensor again.

Or, you can permanently change the baudrate by editing /boot/flash/config.txt with the following line (requires reboot to take effect):

dtparam=i2c_baudrate=9600

Usage¶

To use a sensor, you have to tell the I2C adapter the driver and I2C address to use. When you write this to /sys/bus/i2c/devices/i2c-1/new_device, a new sensor device will appear in /sys/class/lego-sensor/ which can be used as you would any other sensor.

Tip

You can find the driver name and default I2C address in the sensor information pages.

Example: Loading Microinfinity CruizCore XG1300L driver manually:

sudo sh -c 'echo "mi-xg1300l 0x01" > /sys/bus/i2c/devices/i2c-1/new_device'

I2C Sensor Driver¶

There is currently not a standard I2C adapter driver for BrickPi/BrickPi+ (i.e. You will not find /dev/i2c-X for the BrickPi input ports. Instead, this driver is used for working with NXT/I2C Sensors.

To load this driver, set the BrickPi input port to nxt-i2c mode and then write the driver name and I2C address of the sensor to the set_device attribute. You can find the driver name and default I2C address on the sensor’s information page.

Example:

echo "nxt-i2c" > /sys/class/lego-port/port0/mode
echo "ht-angle 0x01" > /sys/class/lego-port/port0/set_device

Once the driver has been loaded, there will be a new sensor device node added in the The lego-sensor Subsytem.

Unfortunately, some sensors require special operations that are not currently supported in this driver, so attempting to use one of those sensors will fail (check dmesg). If you have a BrickPi, you can use Input Port 5 instead.

Output Ports¶

BrickPi3 has four output ports labeled M1, M2, M3 and M4. These ports are very similar to EV3 output ports with a motor controller and quadrature encoder feedback. However, they cannot automatically detected when a motor is attached or removed. By default, the NXT motor driver is already loaded for these ports, so you don’t have to set the mode unless you want to use a different type of driver.

General Info¶

Module	`brickpi`
Driver name	`brickpi-out-port`
Connection types	tacho-motor, dc-motor, led
Connection prefix	`M` [6]
Number of modes	3

Modes¶

Name	Description
`tacho-motor`	NXT/EV3 Large Motor
`dc-motor`	RCX/Power Functions motor
`led`	RCX/Power Functions LED

Notes¶

[6]	The full port name includes the parent device node. So, the `address` attribute will return something like `ttyAMA0:M1`.

Battery¶

Note

The BrickPi+ battery driver is only available on BrickPi+ (HW v2.8), not the earlier BrickPi models.

This driver is used to get information about the BrickPi+ battery.
It uses the power_supply subsytem.
It registers a sysfs device node at /sys/class/power_supply/brickpi-battery/.

Tip

This driver is enabled by the line dtparam=brickpi_battery=okay in /boot/flash/config.txt.

Sysfs Attributes¶
`scope`	Always returns `System`.
`voltage_now`	Returns the battery voltage in microvolts.

Line Discipline¶

This driver is a tty line discipline that runs on top of a serial port. It is the core driver that facilitates communication between the Rapberry Pi and the BrickPi.

The driver is loaded by attaching the line discipline:

sudo ldattach 29 /dev/ttyAMA0

Once this driver is successfully loaded, it will load the input and output drivers for the BrickPi.

Tip

Technically, it is possible to use the BrickPi with any 3.3V serial port. It does not necessarily have to be use with a Rapsberry Pi.

Dexter Industries BrickPi3¶

This page describes the drivers that are specific to Dexter Industries BrickPi3 These controllers are LEGO MINDSTORMS compatible addon boards for Raspberry Pi. Unlike the previous versions of BrickPi, the BrickPi3 uses the SPI interface on the Raspberry Pi to communicate.

You can confirm that the brickpi3 module has loaded successfully by checking dmesg. You should see something like this:

[    3.053862] brickpi3 spi0.1: Mfg: Dexter Industries
[    3.060030] brickpi3 spi0.1: Board: BrickPi3
[    3.063114] brickpi3 spi0.1: HW: 3.2.1
[    3.076690] brickpi3 spi0.1: FW: 1.2.0
[    3.090078] brickpi3 spi0.1: ID: FAD3CABB504B5354392E314BFF0F2C38

Input Ports¶

The BrickPi3 has four input ports, labeled S1, S2, S3 and S4. These ports are similar to the input ports on the EV3, but lack the ability to automatically detect sensors.

General Info¶

Module	`brickpi3`
Driver name	`brickpi3-in-port`
Connection types	NXT/Analog, NXT/I2C, EV3/Analog, EV3/UART
Connection prefix	`S` [1]
Number of modes	6

Modes¶

Name	Description
`none`	No sensor
`nxt-analog` [2]	NXT/Analog sensor
`nxt-color`	LEGO NXT Color sensor
`nxt-i2c` [3]	NXT/I2C sensor
`ev3-analog` [4]	EV3/Analog sensor
`ev3-uart` [5]	EV3/UART sensor

Notes¶

[1]	The full port name includes the parent device node. So, the `address` attribute will return something like `spi0.1:S1`.

[2]	The `nxt-analog` driver will be loaded when this mode is set. You must manually specify the correct driver for your sensor using `set_device` if you want to use another driver. Any driver with a connection type of NXT/Analog is allowed.

[3] No sensors are loaded by default. You must manually specify the sensor that is connected and its address by using the set_device attribute. This is equivalent to manually loading I2C devices. The sensor port address will be the BrickPi3 port address with :i2c and the decimal I2C address appended.

[4]	Only the LEGO EV3 Touch sensor is supported. The `lego-ev3-touch` sensor driver will load automatically when this port mode is set.

[5]	Only the LEGO EV3 Ultrasonic, Color, Gyro, and Infrared sensors are supported. They cannot be automatically detected, so you must specify the sensor manually using the `set_device` attribute. No sensor drivers are loaded by default.

I2C Adapters¶

The brickpi3 modules creates one I2C adapter for each input port. These are available at /dev/i2c-X where X is the number of the input port plus 2. The adapters can only be used when the port is set to nxt-i2c mode. Only SMBUS messages are supported and are limited to 16 bytes.

Output Ports¶

The BrickPi3 has four output ports, labeled M1, M2, M3 and M4, for driving motors or other devices. The ports are similar to the output ports on the EV3, except that they cannot automatically detect when a motor is connected. By default, the lego-nxt-motor driver is loaded, so you don’t need to manually set the mode or device unless you want to use something else.

General Info¶

Module	`brickpi3`
Driver name	`brickpi3-out-port`
Connection types	tacho-motor, dc-motor, led
Connection prefix	`M` [6]
Number of modes	3

Modes¶

Name	Description
`tacho-motor`	NXT/EV3 Large Motor
`dc-motor`	RCX/Power Functions motor
`led`	RCX/Power Functions LED

Notes¶

[6]	The full port name includes the parent device node. So, the `address` attribute will return something like `spi0.1:M1`.

LEDs¶

The BrickPi3 has one user-controllable LED. It is turned on by default when the brickpi3 module is loaded. It uses the mainline kernel LEDs class subsystem. You can find it in sysfs at /sys/class/leds/brickpi3:amber:ev3dev.

Battery¶

This driver is used to get information about the BrickPi battery.
It uses the power_supply subsytem.
It registers a sysfs device node at /sys/class/power_supply/brickpi-battery/.

Sysfs Attributes¶
`scope`	Always returns `System`.
`voltage_now`	Returns the battery voltage in microvolts.

Voltages¶

The BrickPi3 monitors four different voltages for the on-board regulators (these are coming from the BrickPi3 itself, not the Raspberry Pi). There is one for 3.3V, one for 5V, one for 9V and one for direct battery voltage.

These voltages are read using the mainline kernel Industrial I/O driver. You can read the values at /sys/bus/iio/devices/iio\:device0/in_voltage_N_input where N is one of 3V3, 5V, 9V or VCC (battery).

Tip

You can use the Battery driver for monitoring the battery instead of using this driver.

Mindsensors PiStorms¶

The pistorms module provides drivers for most of the functionality of the mindsensors.com PiStorms including lego-port class instances for the input and output ports, an evdev driver (evdev is not to be confused with ev3dev) for the touchscreen and GO button, a power_supply driver for monitoring the battery and an leds driver for the multi-color LEDs.

Input Ports¶

The PiStorms has four LEGO MINDSTORMS EV3 compatible input ports. There are some differences though. Sensors cannot be automatically detected, so you must manually specify the mode of the port before using a sensors. And in many cases, you must also manually specify the type of sensor that is attached. Furthermore, all four ports share a single I2C adapter (master) instead of each port having its own.

General Info¶

Module	`pistorms`
Driver name	`pistorms-in-port`
Connection types	NXT/Analog, NXT/Color, NXT/I2C, Other/I2C, EV3/Analog, EV3/UART
Connection prefix	`S` [1]
Number of modes	6

Modes¶

Name	Description
`none`	No sensor
`nxt-analog` [2]	NXT/Analog sensor
`nxt-color`	NXT/Color sensor
`i2c-thru` [3]	I2C pass through
`ev3-analog` [4]	EV3/Analog sensor
`ev3-uart` [5]	EV3/UART sensor

Notes¶

[1]	The full `address` is in the format: pistorms:B<b><prefix><n> For example, if we are looking at the port labeled “BBS2” on the PiStorms, the address will be `pistorms:BBS2`.

[2]	The generic `nxt-analog` driver will be loaded when this mode is set. You must manually specify thecorrect driver for your sensor using `set_device` if you want to use another driver. Any driver with a connection type of NXT/Analog is allowed.

[3]

I2C signals are passed through the input port to i2c_arm on the Raspberry Pi. This means that all 4 input ports share the same I2C master and the devices must have different addresses even if they are connected to different ports on the PiStorms.

NXT/I2C sensors will be automatically detected, otherwise you must manually specify the sensor that is connected by using the set_device attribute.

[4]	Only the LEGO EV3 Touch sensor is supported. The driver will load by default.

[5]	Only the LEGO EV3 Ultrasonic, Color, Gyro, and Infrared sensors are supported. When this mode is set, a sensor device will be registered for the type of sensor that is attached (or was most recently attached).

Output Ports¶

The PiStorms has four LEGO MINDSTORMS compatible output ports. Unlike the EV3, motors cannot be automatically detected when attached. By default, the ports are configured with the NXT motor driver, which will work for most cases.

General Info¶

Module	`pistorms`
Driver name	`pistorms-out-port`
Connection types	tacho-motor
Connection prefix	`M` [6]
Number of modes	1

Modes¶

Name	Description
`tacho-motor`	NXT/EV3 Large Motor

Notes¶

[6]	The full address will be something like `pistorms:BAM1`.

Touchscreen and GO Button¶

The pistorms module registers an input device node for the touchscreen an the GO button on the PiStorms.

The touchscreen provides ABS_X and ABS_Y events to indicate where the screen was touched and BTN_TOUCH to indicate when a touch event starts and stops.

The GO button is mapped to KEY_ENTER.

LEDs¶

The pistorms module provides six LED devices for controlling the LEDs on the Pistorms. There are two tri-color LEDs. Each component (red, green, blue) is controlled separately.

The device nodes can be found at /sys/class/leds/pistorms:B<bank>:<color>:ev3dev where <bank>> is A or B and <color> is red, green or blue.

Note

Some models of PiStorms only have one LED. The driver will still provide controls for two, but only one will actually work.

Battery¶

This driver is used to get information about the PiStorms battery.
It uses the power_supply subsytem.
It registers a sysfs device node at /sys/class/power_supply/pistorms-battery/.

Sysfs Attributes¶
`scope`	Always returns `System`.
`voltage_now`	Returns the battery voltage in microvolts.

FatcatLab EVB¶

The FatcatLab EVB is a LEGO MINDSTORMS EV3 compatible cape for BeagleBone.

Input / Output Ports¶

By default, a sysfs device is created for each input and output port on the EVB. See the input ports and output ports driver descriptions for more information on how these work. There is a single module for input and output ports named evb_ports. This module has some module parameters.

Module Parameters¶
Name	Description
`disable_in_port`	Used to prevent the input port device from being loaded. This is useful if you want to use input port 1 for printing kernel messages this if you want while you are debugging the Linux kernel. You may also want to do to control the input port gpios directly.
`disable_out_port`	Used to prevent the output port from being loaded. This leaves the pwm device and gpios used by the port free to be controlled directly or used by other drivers.

Input Ports¶

FatcatLab EVB has four input ports labeled 1, 2, 3 and 4. These ports are used with LEGO MINDSTORMS EV3 and NXT compatible sensors and other devices. Most sensors can be automatically detected when plugged in. Unlike the EV3, however, NXT analog sensors cannot be detected, so to use these sensors, the port has to be placed in nxt-analog mode manually.

General Info¶

Module	`evb_ports`
Driver name	`evb-input-port`
Connection types	NXT/Analog, NXT/I2C, Other/I2C, EV3/Analog, EV3/UART, Other/UART
Connection prefix	`in`
Number of modes	9

Modes¶

Name	Description
`auto` [1]	Automatically detect most sensors.
`nxt-analog` [2]	Configures the port for NXT/Analog sensors
`nxt-color` [3]	Configures the port for the LEGO NXT Color sensor
`nxt-i2c`	Configure for I2C communications and load the `nxt-i2c-host` device.
`other-i2c`	Configure for I2C communications but do not probe for NXT sensors.
`ev3-analog`	Configures the port for EV3/Analog sensors
`ev3-uart`	Configure for UART communications and load the `ev3-uart-host` device.
`other-uart`	Configure for UART communications but do not load any device.
`raw` [4]	Provide access to low level drivers.

Notes¶

[1]	In auto mode, the port will attempt to automatically detect the type of sensor that was connected and load the appropriate driver. See the list of Supported Sensors to determine if a sensor can be automatically detected.

[2]	This loads the generic NXT/Analog sensor `nxt-analog` driver. Use `set_device` to load the appropriate device/driver.

[3]	NXT Color sensor driver has not been implemented yet, so right now, this mode does nothing.

[4]	Exports gpios and analog/digital converter values to sysfs so that they can be controlled directly.

Input Port I2C Adapters¶

The ev3dev PRU firmware for FatcatLab EVB creates one I2C adapter for each input port. These are available at /dev/i2c-X where X is the number of the input port plus 2. The adapters can only be used when the port is set to nxt-i2c or other-i2c mode.

Output Ports¶

The FatcatLab EVB has four output ports labeled A, B, C and D. These ports are used with LEGO MINDSTORMS EV3, NXT and RCX compatible motors and other devices. EV3 motors can be automatically detected when plugged in. Other motors with position feedback (such as the NXT motor) are usually detected as an EV3 Large Motor. RCX motors and LEDs cannot be automatically detected and the mode of the output port must be manually set to use these types of devices.

General Info¶

Module	`evb_ports`
Driver name	`evb-output-port`
Connection types	tacho-motor, dc-motor, led
Connection prefix	`out`
Number of modes	5

Modes¶

Name	Description
`auto` [5]	Automatically detect motors when they are connected.
`tacho-motor` [6]	Configure the port for NXT/EV3 motors.
`dc-motor` [7]	Load the port for RCX/Power Functions motors.
`led` [8]	Load the port for RCX/Power Functions LEDs.
`raw` [9]	Provide access to low level drivers.

Notes¶

[5]	Only the EV3/NXT large motors and the EV3 medium motor can be automatically detected. All other devices must be manually configured.

[6]	Configures the port to use the tacho-motor Subsystem. The default driver is the EV3 Large Motor (`lego-ev3-l-motor`). You can change the driver using the `set_device` attribute.

[7]	This can be use with MINDSTORMS RCX motors, Power Functions motors and any other “plain” DC motor. By “plain”, we mean the motor is just a motor without any feedback.

[8]	This can be used with MINDSTORMS RCX LEDs, Power Functions LEDs or any other LED connected to pins 1 and 2 of the output port.

[9]	Exports gpios, pwm and analog/digital converter values to sysfs so that they can be controlled directly.

Buttons / Joystick¶

The EVB has a directional joystick and a single button for user input. These are mapped to keyboard keys so that they provided the same input signals as the EV3.

Note

Simultaneous button presses are ignored.

Button map¶
Button/Direction	Linux key code (value)
Back button press	`KEY_BACKSPACE` (14)
Joystick button press	`KEY_ENTER` (28)
Joystick up	`KEY_UP` (103)
Joystick left	`KEY_ENTER` (105)
Joystick right	`KEY_ENTER` (106)
Joystick down	`KEY_DOWN` (108)

Battery¶

This driver is used to get information about the FatcatLab EVB battery.
It uses the power_supply subsytem.
It registers a sysfs device node at /sys/class/power_supply/evb-battery/.

Sysfs Attributes¶
`scope`	Always returns `System`.
`voltage_now`	Returns the battery voltage in microvolts.

Sound¶

The snd-evb module provedes an ALSA driver for PCM playback and a Linux input device with sound capabilities (EV_SND) for producing tones.

The ALSA driver can be used with standard tools such as alsamixer and aplay. Tones can be produced by using the beep command, ioctls such as KDMKTONE (must run on local console or as root for ioctls) or by writing SND_* events to the event device (must be member of input group for this).

User Space Drivers¶

Configfs Interface¶

This driver provides a configfs interface for creating user-defined devices that use the various ev3dev drivers. Currently, only ports, sensors and LEDs are implemented. Motors could be added in the future.

Usage¶

Note

All commands assume root privileges.

Here is an example of how to create a port and a sensor:

Make sure module is loaded:
```
modprobe user-lego-configfs
```
Go to the configfs directory for this driver:
```
cd /sys/kernel/config/lego_user_device
```
Create a new port called p1:
```
mkdir p1
```
Check out the new port - there should be live and sensors directories:
```
cd p1
ls
```
This also creates a new port that is linked to sys/class/lego-port:
```
ls /sys/devices/lego_user_device/lego-port/
```
Now create a sensor named s1 attached to this port:
```
mkdir sensors/s1
```
Check out the sensor:
```
ls sensors/s1
```
These attributes correspond to attributes in the lego-sensor class. Set them as appropriate. For example:
```
echo "my-driver" > sensors/s1/driver_name
```
Once the attributes have been set, export the sensor by linking it to live:
```
ln -s sensors/s1 live
```
There will be two new devices created, one in /sys/class/user-lego-sensor/ and one in /sys/class/lego-sensor. The lego-sensor class device is used just as any other sensor. The user-lego-sensor device is used to feed data into the sensor. See the user-lego-sensor-class docs for more info.
To remove the sensor and port, perform the operations in reverse:
```
rm link/s1
rmdir sensors/s1
cd ..
rmdir p1
```

The user-lego-sensor Subsystem¶

The user-lego-sensor class provides an interface for implementing user-defined sensors in userspace.

Identifying sensors¶

Since the name of the sensor<N> device node does not correspond to the port that a sensor is plugged in to, you must look at the address attribute if you need to know which port a sensor is plugged in to. This will match the address of the corresponding sensor in the lego-sensor class.

Sysfs¶

Sensors can be found at /sys/class/user-lego-sensor/sensor<N>, where <N> is incremented each time a sensor is loaded.

Note

The number <N> does not correspond to the address of sensor.

sysfs attributes¶
Attribute	Access	Description
`bin_data`	write-only	Writing stores the data which can be read using the `bin_data` and `value<N>` attributes in the corresponding `lego-sensor` class device.
`text_value`	write-only	Writing stores the value which can be read using the `text_value` attribute in the corresponding lego-sensor class device. It is currently limited to 512 bytes in length.

Appendix A: Sensor Data¶

This page contains sensor-specific data for each type of supported sensor.

Generic EV3 Analog Sensor¶

General Info¶

Driver Name	`ev3-analog-XX`
Connection Type	EV3/Analog
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`ANALOG`	Raw analog value	`V` (volts)	3	1	`value0`: Voltage (0 - 5000)

Commands¶

This sensor does not support commands.

Generic NXT Analog Sensor¶

General Info¶

Driver Name	`nxt-analog`
Connection Type	NXT/Analog
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`ANALOG-0`	Raw analog value	`V` (volts)	3	1	`value0`: Voltage (0 - 5000)
`ANALOG-1`	Raw analog value - pin 5 high	`V` (volts)	3	1	`value0`: Voltage (0 - 5000)

Commands¶

This sensor does not support commands.

Charmed Labs Pixy (CMUcam5) for LEGO¶

General Info¶

Driver Name	`pixy-lego`
Website	charmedlabs.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`Pixy`
Product ID	`Pixy`
Number of Modes	8

Modes¶

Mode	Description	Units	Num. Values	Values
`ALL`	All	none	6	`value0`: Signature low byte `value1`: Signature high byte `value2`: X `value3`: Y `value4`: Width `value5`: Height
`SIG1`	Signature #1	none	5	`value0`: Count `value1`: X `value2`: Y `value3`: Width `value4`: Height
`SIG2`	Signature #2	none	5	`value0`: Count `value1`: X `value2`: Y `value3`: Width `value4`: Height
`SIG3`	Signature #3	none	5	`value0`: Count `value1`: X `value2`: Y `value3`: Width `value4`: Height
`SIG4`	Signature #4	none	5	`value0`: Count `value1`: X `value2`: Y `value3`: Width `value4`: Height
`SIG5`	Signature #5	none	5	`value0`: Count `value1`: X `value2`: Y `value3`: Width `value4`: Height
`SIG6`	Signature #6	none	5	`value0`: Count `value1`: X `value2`: Y `value3`: Width `value4`: Height
`SIG7`	Signature #7	none	5	`value0`: Count `value1`: X `value2`: Y `value3`: Width `value4`: Height

Commands¶

This sensor does not support commands.

Dexter Industries Flexible Sensor for Mindstorms NXT¶

General Info¶

Driver Name	`di-dflex`
Website	www.dexterindustries.com
Connection Type	NXT/Analog
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`FLEX`	Flex	none	0	1	`value0`: Flex (0-100)

Commands¶

This sensor does not support commands.

Fatcatlab 9DOF Sensor¶

General Info¶

Driver Name	`fcl-9dof`
Website	fatcatlab.com
Connection Type	EV3/UART
Number of Modes	3

Modes¶

Mode Description Units Decimals Num. Values Values

GYRO

Gyroscope

d/s (degrees per second)

1

3

value0: X-axis rotational speed (-20000 to 20000)

value1: Y-axis rotational speed (-20000 to 20000)

value2: Z-axis rotational speed (-20000 to 20000)

ACC

Accelerometer

g (standard gravity)

3

value0: X-axis acceleration (-16000 to 16000)

value1: Y-axis acceleration (-16000 to 16000)

value2: Z-axis acceleration (-16000 to 16000)

MAGNET

Magnetometer

uT (microteslas)

0

3

value0: X-axis magnetic flux density (-4800 to 4800)

value1: Y-axis magnetic flux density (-4800 to 4800)

value2: Z-axis magnetic flux density (-4800 to 4800)

Commands¶

This sensor does not support commands.

Fatcatlab ADC Adapter¶

General Info¶

Driver Name	`fcl-adc`
Website	fatcatlab.com
Connection Type	EV3/UART
Number of Modes	3

Modes¶

Mode Description Units Decimals Num. Values Values

CH1-VOLTAGE Channel 1 mV (millivolts) 0 1 value0: Voltage (0 to 3300)

CH2-VOLTAGE Channel 2 mV (millivolts) 0 1 value0: Voltage (0 to 3300)

VOLTAGE

Both Channels

mV (millivolts)

0

2

value0: Channel 1 Voltage (0 to 3300)

value1: Channel 2 Voltage (0 to 3300)

Commands¶

This sensor does not support commands.

Fatcatlab Altitude Sensor¶

General Info¶

Driver Name	`fcl-altitude`
Website	fatcatlab.com
Connection Type	EV3/UART
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`PRESSURE`	Pressure	`hPa` (hectopascals)	1	1	`value0`: Pressure (3000 to 11000)
`ALTITUDE`	Altitude	`m` (meters)	1	1	`value0`: Altitude (-5000 to 90000)

Commands¶

This sensor does not support commands.

Fatcatlab Gesture Sensor¶

General Info¶

Driver Name	`fcl-gesture`
Website	fatcatlab.com
Connection Type	EV3/UART
Number of Modes	4

Modes¶

Mode	Description	Units	Num. Values	Values
`GESTURE`	Gesture	none	1	`value0`: Gesture (0 to 6) [1]
`PROXIMITY`	Proximity	none	1	`value0`: Voltage (0 to 127)
`RGB-RAW`	Color	none	3	`value0`: Red `value1`: Green `value2`: Blue
`CLEAR` [2]	Clear	none	1	`value0`: Always 1

Commands¶

This sensor does not support commands.

Notes¶

[1]

Gesture Values:

Value	Description
0	none
1	left
2	right
3	up
4	down
5	near
6	far

[2]	The `CLEAR` mode is used to reset the value of the `GESTURE` mode back to zero.

Fatcatlab Humidity Sensor¶

General Info¶

Driver Name	`fcl-humidity`
Website	fatcatlab.com
Connection Type	EV3/UART
Number of Modes	3

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`CENTIGRADE`	Temperature (Celsius)	`C` (degrees Celsius)	1	1	`value0`: Temperature (-400 to 1250)
`FAHRENHEIT`	Temperature (Fahrenheit)	`F` (degrees Fahrenheit)	1	1	`value0`: Temperature (-400 to 2570)
`HUMIDITY`	Humidity	`%RH` (percent relative humidity)	1	1	`value0`: Humidity (0 to 1000)

Commands¶

This sensor does not support commands.

Fatcatlab IR Receiver¶

General Info¶

Driver Name	`fcl-ir`
Website	fatcatlab.com
Connection Type	EV3/UART
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`IR DATA`	IR Remote Control	none	0	1	`value0`: Channel 1 (0 to 60) [3]

Commands¶

This sensor does not support commands.

Notes¶

[3]

Button values:

Value	Button
0	none
1-9	1-9 (digits)
10	0 (zero)
11	+ (plus)
12	- (minus)
13	⏮ (previous)
14	⏭ (next)
15	⏯ (play/pause)
21	OK
22	↰ (back)
30	⏻ (power)
40	MENU
50	🔇 (mute)
60	MODE

Fatcatlab Light Sensor¶

General Info¶

Driver Name	`fcl-light`
Website	fatcatlab.com
Connection Type	EV3/UART
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`ILLUMINANCE`	Illuminance	`lx` (lux)	0	1	`value0`: Illuminance (0 to 65535)

Commands¶

This sensor does not support commands.

HiTechnic NXT Color Sensor¶

General Info¶

Driver Name	`ht-nxt-color`
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HiTechnc`
Product ID	`Color`
Number of Modes	7

Modes¶

Mode	Description	Units	Num. Values	Values
`COLOR`	Color	none	1	`value0`: Color (0 to 17) [4]
`RED`	Red component	none	1	`value0`: Reflected light intensity (0 to 255)
`GREEN`	Green component	none	1	`value0`: Reflected light intensity (0 to 255)
`BLUE`	Blue component	none	1	`value0`: Reflected light intensity (0 to 255)
`RAW`	Raw values	none	3	`value0`: Red Component (0 to 255) `value1`: Green Component (0 to 255) `value2`: Blue Component (0 to 255)
`NORM`	Normalized values	none	4	`value0`: Red Component (0 to 255) `value1`: Green Component (0 to 255) `value2`: Blue Component (0 to 255) `value3`: ??? Component (0 to 255)
`ALL`	All values	none	4	`value0`: Color (0 to 17) [4] `value1`: Red Component (0 to 255) `value2`: Green Component (0 to 255) `value3`: Blue Component (0 to 255)

Commands¶

This sensor does not support commands.

Notes¶

[4]	(1, 2) Color Values:

HiTechnic NXT Angle Sensor¶

General Info¶

Driver Name	`ht-nxt-angle`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HITECHNC`
Product ID	`AnglSnsr`
Number of Modes	3

Modes¶

Mode	Description	Units	Num. Values	Values
`ANGLE`	Angle	`deg` (degrees)	1	`value0`: Angle (0 to 359)
`ANGLE-ACC`	Accumulated angle	`deg` (degrees)	1	`value0`: Angle (-2147483648 to 2147483647)
`SPEED`	Rotational speed	`RPM` (revolutions per minute)	1	`value0`: Angle (-32768 to 32768)

Commands¶

Command	Description
`RESET`	Reset accumulated angle
`CAL` [5]	Reset angle and accumulated angle and save to EEPROM

Notes¶

[5]	When Calibrating the sensor wait least 25ms before further reads from the sensor. That means disable polling by setting `poll_ms` to 0 before sending this command.

HiTechnic NXT Acceleration / Tilt Sensor¶

General Info¶

Driver Name	`ht-nxt-accel`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HITECHNC`
Product ID	`Accel.`
Number of Modes	2

Modes¶

Mode Description Units Decimals Num. Values Values

ACCEL Single-axis acceleration none 0 1 value0: Acceleration (coarse value) [6]

ALL

Three-axis acceleration

none

0

6

value0: X-axis acceleration (most significant byte)

value1: Y-axis acceleration (most significant byte)

value2: Z-axis acceleration (most significant byte)

value3: X-axis acceleration (least significant byte) [7]

value4: Y-axis acceleration (least significant byte) [7]

value5: Z-axis acceleration (least significant byte) [7]

Commands¶

This sensor does not support commands.

Notes¶

[6]	Value is 8 most significant bits out of 10-bit total resolution.

[7]	(1, 2, 3) Only the 2 most significant bits are used. Actual value is `MSB << 2 + LSB >> 6` or `MSB << 2 + LSB & 0x03` (can someone confirm which one?).

HiTechnic NXT Barometric Sensor¶

General Info¶

Driver Name	`ht-nxt-barometric`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HiTechnc`
Product ID	`Barometr`
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`PRESS`	Barometric Pressure	`m` (???)	1	1	`value0`: Absolute Pressure (0 to 3000)
`TEMP`	Temperature	`C` (degrees Celsius)	1	1	`value0`: Absolute Pressure (0 to 1000)

Commands¶

This sensor does not support commands.

HiTechnic NXT Color Sensor V2¶

General Info¶

Driver Name	`ht-nxt-color-v2`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HiTechnc`
Product ID	`ColorPD`
Number of Modes	8

Modes¶

Mode	Description	Units	Num. Values	Values
`COLOR`	Color	none	1	`value0`: Color (0 to 17) [8]
`RED`	Red component	none	1	`value0`: Reflected light intensity (0 to 255)
`GREEN`	Green component	none	1	`value0`: Reflected light intensity (0 to 255)
`BLUE`	Blue component	none	1	`value0`: Reflected light intensity (0 to 255)
`WHITE`	White component	none	1	`value0`: Reflected light intensity (0 to 255)
`NORM`	Normalized values	none	4	`value0`: Red Component (0 to 255) `value1`: Green Component (0 to 255) `value2`: Blue Component (0 to 255) `value3`: White Component (0 to 255)
`ALL`	All values	none	5	`value0`: Red Component (0 to 255) `value1`: Green Component (0 to 255) `value2`: Blue Component (0 to 255) `value3`: White Component (0 to 255) `value4`: ??? (0 to 255)
`RAW`	Raw values	none	4	`value0`: Red Component (0 to 255) `value1`: Green Component (0 to 255) `value2`: Blue Component (0 to 255) `value3`: White Component (0 to 255)

Commands¶

This sensor does not support commands.

Notes¶

[8]	Color Values:

HiTechnic NXT EOPD¶

General Info¶

Driver Name	`ht-nxt-eopd`
Website	www.hitechnic.com
Connection Type	NXT/Analog
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`LONG`	Proximity (long range)	none	0	1	`value0`: Proximity (0-100) [9]
`SHORT`	Proximity (short range)	none	0	1	`value0`: Proximity (0-100) [9]

Commands¶

This sensor does not support commands.

Notes¶

[9]	(1, 2) This value is the square root of the raw value. You can derive a value proportional (linear) to distance by dividing a constant by this value, e.g. `35 / value0`.

HiTechnic NXT Force Sensor¶

General Info¶

Driver Name	`ht-nxt-force`
Website	www.hitechnic.com
Connection Type	NXT/Analog
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`FORCE`	Raw value (non-linear)	none	0	1	`value0`: (0-1023)

Commands¶

This sensor does not support commands.

HiTechnic NXT Gyro Sensor¶

General Info¶

Driver Name	`ht-nxt-gyro`
Website	www.hitechnic.com
Connection Type	NXT/Analog
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`GYRO`	Angular speed	`d/s` (degrees per second)	0	1	`value0`: Angular speed (-540 to 400)

Commands¶

This sensor does not support commands.

HiTechnic NXT IRLink Sensor¶

General Info¶

Driver Name	`ht-nxt-ir-link`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HiTechnc`
Product ID	`IRLink`
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`IRLINK`	???	none	0	1	`value0`: ???

Commands¶

This sensor does not support commands.

HiTechnic NXT IRReceiver Sensor¶

General Info¶

Driver Name	`ht-nxt-ir-receiver`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HiTechnc`
Product ID	`IRRecv`
Number of Modes	2

Modes¶

Mode Description Units Decimals Num. Values Values

1-MOTOR Single Motor Control pct (percent) 0 1 value0: Motor 1A Speed (-128 and -100 to 100) [10] [11]

8-MOTOR

Eight Motor Controls

pct (percent)

0

8

value0: Motor 1A Speed (-128 and -100 to 100) [10] [11]

value1: Motor 1B Speed (-128 and -100 to 100) [10] [11]

value2: Motor 2A Speed (-128 and -100 to 100) [10] [11]

value3: Motor 2B Speed (-128 and -100 to 100) [10] [11]

value4: Motor 3A Speed (-128 and -100 to 100) [10] [11]

value5: Motor 3B Speed (-128 and -100 to 100) [10] [11]

value6: Motor 4A Speed (-128 and -100 to 100) [10] [11]

value7: Motor 4B Speed (-128 and -100 to 100) [10] [11]

Commands¶

This sensor does not support commands.

Notes¶

[10]	(1, 2, 3, 4, 5, 6, 7, 8, 9) Value of -128 is brake. Speed values only occur in discrete steps (-100, -86, -72, -58, -44, -30, -16, 0, 16, 30, 44, 58, 72, 86 and 100).

[11]	(1, 2, 3, 4, 5, 6, 7, 8, 9) In the description, “Motor NX”, the number N is the channel, and the letter X is the channel. “A”” is the red/left control and “B”” is the blue/right control.

HiTechnic NXT PIR Sensor¶

General Info¶

Driver Name	`ht-nxt-pir`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HITECHNC`
Product ID	`PIR`
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`PROX`	IR Proximity	`pct` (percent)	0	1	`value0`: Proximity (-100 to 100)

Commands¶

This sensor does not support commands.

HiTechnic NXT Compass Sensor¶

General Info¶

Driver Name	`ht-nxt-compass`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`HITECHNC` (or `HiTechnc`)
Product ID	`Compass`
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`COMPASS`	Compass Direction	`deg` (degrees)	0	1	`value0`: Direction (0 to 359)

Commands¶

This sensor does not support commands.

HiTechnic NXT Magnetic Sensor¶

General Info¶

Driver Name	`ht-nxt-mag`
Website	www.hitechnic.com
Connection Type	NXT/Analog
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`MAG`	Magnetic field???	none	0	1	`value0`: ???

Commands¶

This sensor does not support commands.

HiTechnic NXT IRSeeker V2¶

General Info¶

Driver Name	`ht-nxt-ir-seek-v2`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x08
Vendor ID	`HiTechnc`
Product ID	`NewIRDir`
Number of Modes	4

Modes¶

Mode	Description	Units	Num. Values	Values
`DC`	Direction (unmodulated)	none	1	`value0`: Direction (0 to 9) [12]
`AC`	Direction (modulated)	none	1	`value0`: Direction (0 to 9) [12]
`DC-ALL`	All values (unmodulated)	none	7	`value0`: Direction (0 to 9) [12] `value1`: Sensor 1 signal strength (0 to 9) [12] `value2`: Sensor 2 signal strength (0 to 9) [12] `value3`: Sensor 3 signal strength (0 to 9) [12] `value4`: Sensor 4 signal strength (0 to 9) [12] `value5`: Sensor 5 signal strength (0 to 9) [12] `value6`: Sensor mean (0 to 9) [12]
`AC-ALL`	All values (modulated)	none	6	`value0`: Direction (0 to 9) [12] `value1`: Sensor 1 signal strength (0 to 9) [12] `value2`: Sensor 2 signal strength (0 to 9) [12] `value3`: Sensor 3 signal strength (0 to 9) [12] `value4`: Sensor 4 signal strength (0 to 9) [12] `value5`: Sensor 5 signal strength (0 to 9) [12]

Commands¶

This sensor does not support commands.

Notes¶

[12]

(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)

Direction values:

Value	Description
0	No signal
1	Far left
...
5	Center
...
9	Far right

HiTechnic NXT Sensor Multiplexer¶

General Info¶

Driver Name	`ht-nxt-smux`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x08
Vendor ID	`HiTechnc`
Product ID	`SensrMUX`
Number of Modes	1

Modes¶

Mode Description Units Decimals Num. Values Values

MUX

Status

none

0

2

value0: Run state [13]

value1: Status [14]

Commands¶

Command	Description
`HALT`	Halt
`DETECT` [15] [16]	Start auto-detection
`RUN`	Run

Notes¶

[13]

Run state:

Value	Description
0	Halt
1	Detect
2	Run

[14]

Status bits:

Bit	Description
0	Low/no battery
1	Running
2	Halted
3	Error

[15]	The sensor mux must be halted before sending the detect command, otherwise it will result an error (-EPERM).

[16]	Only these sensors can be automatically detected: LEGO NXT Ultrasonic HiTechnic NXT Compass HiTechnic NXT Color HiTechnic NXT Acceleration / Tilt HiTechnic NXT IR Seeker HiTechnic Super Pro HiTechnic NXT Color V2 HiTechnic NXT IR Seeker V2

HiTechnic NXT SuperPro Prototype Board¶

General Info¶

Driver Name	`ht-super-pro`
Website	www.hitechnic.com
Connection Type	NXT/I2C
Default Address	0x08
Vendor ID	`HiTechnc`
Product ID	`SuperPro`
Number of Modes	5

Modes¶

Mode	Description	Units	Num. Values	Values
`AIN`	Analog inputs	none	4	`value0`: Analog input A0 (0 to 1023) `value1`: Analog input A1 (0 to 1023) `value2`: Analog input A2 (0 to 1023) `value3`: Analog input A3 (0 to 1023)
`DIN`	Digital inputs	none	1	`value0`: Bits B0-B7 (0 to 255)
`DOUT`	Digital outputs	none	1	`value0`: Bits B0-B7 (0 to 255)
`DCTRL`	Digital input/output controls	none	1	`value0`: Bits B0-B7 (0 to 255)
`STROBE`	Strobe output	none	1	`value0`: Bits S0-S3 (0 to 15)
`LED`	LED control	none	1	`value0`: LED state [17]
`AOUT-0`	Analog output O0	none	5	`value0`: Mode `value1`: Frequency, most significant byte `value2`: Frequency, least significant byte `value3`: Voltage, most significant byte `value4`: Voltage, least significant byte
`AOUT-1`	Analog output O1	none	5	`value0`: Mode `value1`: Frequency, most significant byte `value2`: Frequency, least significant byte `value3`: Voltage, most significant byte `value4`: Voltage, least significant byte

Commands¶

This sensor does not support commands.

Notes¶

[17]

LED states:

Value	Description
0	None
1	Red
2	Blue
3	Red and blue

LEGO EV3 Ultrasonic Sensor¶

General Info¶

Driver Name	`lego-ev3-us`
Website	education.lego.com
Connection Type	EV3/UART
Number of Modes	7

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`US-DIST-CM`	Continuous measurement - sets LEDs on, steady	`cm` (centimeters)	1	1	`value0`: Distance (0-2550)
`US-DIST-IN`	Continuous measurement - sets LEDs on, steady	`in` (inches)	1	1	`value0`: Distance (0-1003)
`US-LISTEN`	Listen - sets LEDs on, blinking	none	0	1	`value0`: Presence (0-1) [18]
`US-SI-CM`	Single measurement - LEDs on momentarily when mode is set, then off	`cm` (centimeters)	1	1	`value0`: Distance (0-2550) [19]
`US-SI-IN`	Single measurement - sets LED on momentarily when mode is set, then off	`in` (inches)	1	1	`value0`: Distance (0-1003) [19]
`US-DC-CM` [20]	??? - sets LEDs on, steady	`cm` (centimeters)	1	1	`value0`: Distance (0-2550)
`US-DC-IN` [20]	??? sets LEDs on, steady	`in` (inches)	1	1	`value0`: Distance (0-1003)

Commands¶

This sensor does not support commands.

Notes¶

[18]	A value of 1 indicates that another ultrasonic sensor has been detected. A 1 can also be triggered by a loud noise such as clapping.

[19] (1, 2) A measurement is taken when the mode is set and value0 will not change after this. To take another measurement set the mode again. NOTE: If you write the mode too frequently (e.g. every 100msec), the sensor will sometimes lock up and writing to the mode attribute will return an error. A delay of 250msec between each write to the mode attribute seems sufficient to keep the sensor from locking up.

[20]	(1, 2) Not sure what DC mode stands for. Seems to work like the continuous measurement modes.

LEGO EV3 Gyro Sensor¶

General Info¶

Driver Name	`lego-ev3-gyro`
Website	education.lego.com
Connection Type	EV3/UART
Number of Modes	5

Modes¶

Mode	Description	Units	Num. Values	Values
`GYRO-ANG` [21]	Angle	`deg` (degrees)	1	`value0`: Angle (-32768 to 32767) [22] [23]
`GYRO-RATE` [24]	Rotational Speed	`d/s` (degrees per second)	1	`value0`: Rotational Speed (-440 to 440) [23]
`GYRO-FAS`	Raw sensor value ???	none	1	`value0`: ??? (-1464 to 1535) [23]
`GYRO-G&A` [21] [24]	Angle and Rotational Speed	none	2	`value0`: Angle (-32768 to 32767) [22] [23] `value1`: Rotational Speed (-440 to 440) [23]
`GYRO-CAL`	Calibration ???	none	4	`value0`: ??? `value1`: ??? `value2`: ??? `value3`: ???

Commands¶

This sensor does not support commands.

Notes¶

[21]	(1, 2) The angle in `GYRO-ANG` or `GYRO-G&A` modes can be reset by changing to a different mode and changing back.

[22]	(1, 2) If you spin around too many times in `GYRO-ANG` or `GYRO-G&A` mode, it will get stuck at 32767 or overflow through -32768 depending on when the sensor was manufactured.

[23]	(1, 2, 3, 4, 5) Clockwise is positive when looking at the side of the sensor with the arrows.

[24]	(1, 2) The sensor is calibrated when the `GYRO-RATE` or the `GYRO-G&A` mode is set. If the sensor is moving when setting the mode, the calibration will be off.

LEGO EV3 Color Sensor¶

General Info¶

Driver Name	`lego-ev3-color`
Website	education.lego.com
Connection Type	EV3/UART
Number of Modes	6

Modes¶

Mode	Description	Units	Num. Values	Values
`COL-REFLECT`	Reflected light - sets LED color to red	`pct` (percent)	1	`value0`: Reflected light intensity (0 to 100)
`COL-AMBIENT`	Ambient light - sets LED color to blue (dimly lit)	`pct` (percent)	1	`value0`: Ambient light intensity (0 to 100)
`COL-COLOR`	Color - sets LED color to white (all LEDs rapidly cycling)	`col` (color)	1	`value0`: Detected color (0 to 7) [25]
`REF-RAW`	Raw Reflected - sets LED color to red	none	2	`value0`: ??? (0 to 1020???) `value1`: ??? (0 to 1020???)
`RGB-RAW`	Raw Color Components - sets LED color to white (all LEDs rapidly cycling)	none	3	`value0`: Red (0 to 1020???) `value1`: Green (0 to 1020???) `value2`: Blue (0 to 1020???)
`COL-CAL` [26]	Calibration ??? - sets LED color to red, flashing every 4 seconds, then goes continuous	none	4	`value0`: ??? `value1`: ??? `value2`: ??? `value3`: ???

Commands¶

This sensor does not support commands.

Notes¶

[25]

Color values:

Value	Color
0	none
1	black
2	blue
3	green
4	yellow
5	red
6	white
7	brown

[26]	This mode is not usable. When in `COL-CAL` mode, the color sensor does not respond to the keep-alive sent from the EV3 brick. As a result, the sensor will time out and reset.

LEGO EV3 Touch Sensor¶

General Info¶

Driver Name	`lego-ev3-touch`
Website	education.lego.com
Connection Type	EV3/Analog
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`TOUCH`	Button state	none	0	1	`value0`: State (0 or 1) [27]

Commands¶

This sensor does not support commands.

Notes¶

[27]

Values:

Value	Description
0	Released
1	Pressed

LEGO EV3 Infrared Sensor¶

General Info¶

Driver Name	`lego-ev3-ir`
Website	education.lego.com
Connection Type	EV3/UART
Number of Modes	6

Modes¶

Mode	Description	Units	Num. Values	Values
`IR-PROX`	Proximity	`pct` (percent)	1	`value0`: Distance (0 to 100) [28]
`IR-SEEK`	IR Seeker	`pct` (percent)	8	`value0`: Channel 1 Heading (-25 to 25) [29] `value1`: Channel 1 Distance (-128 and 0 to 100) [30] [31] `value2`: Channel 2 Heading (-25 to 25) [29] `value3`: Channel 2 Distance (-128 and 0 to 100) [30] [31] `value4`: Channel 3 Heading (-25 to 25) [29] `value5`: Channel 3 Distance (-128 and 0 to 100) [30] [31] `value6`: Channel 4 Heading (-25 to 25) [29] `value7`: Channel 4 Distance (-128 and 0 to 100) [30] [31]
`IR-REMOTE`	IR Remote Control	`btn` (button)	4	`value0`: Channel 1 (0 to 11) [32] `value1`: Channel 2 (0 to 11) [32] `value2`: Channel 3 (0 to 11) [32] `value3`: Channel 4 (0 to 11) [32]
`IR-REM-A`	IR Remote Control	none	1	`value0`: Channel 1 [33]
`IR-S-ALT` [34]	Alternate IR Seeker ???	`pct` (percent)	4	`value0`: ??? (0 to 100) `value1`: ??? (0 to 100) `value2`: ??? (0 to 100) `value3`: ??? (0 to 100)
`IR-CAL`	Calibration ???	none	2	`value0`: ??? (0 to 1023) `value1`: ??? (0 to 1023)

Commands¶

This sensor does not support commands.

Notes¶

[28]	100% is approximately 70cm/27in.

[29]	(1, 2, 3, 4) When looking in the same direction as the sensor, -25 is far left and +25 is far right.

[30]	(1, 2, 3, 4) 100% is approximately 200cm/78in.

[31]	(1, 2, 3, 4) The absence of a beacon on a channel can be detected when distance == -128 (and heading == 0).

[32]

(1, 2, 3, 4)

Button values:

Value	Description
0	none
1	red up
2	red down
3	blue up
4	blue down
5	red up and blue up
6	red up and blue down
7	red down and blue up
8	red down and blue down
9	beacon mode on
10	red up and red down
11	blue up and blue down

red == left and blue == right

Pressing more that 2 buttons at one time is not supported. It will usually read 0. Pressing an up/down button while beacon mode is activated with turn off beacon mode.

[33]

Button values:

Value	Blue Down	Blue Up	Red Down	Red Up
262/384
287				X
300			X
309			X	X
330		X
339		X		X
352		X	X
377		X	X	X
390	X
415	X			X
428	X		X
437	X		X	X
458	X	X
467	X	X		X
480	X	X	X
505	X	X	X	X

X = button pressed

The most significant byte is always 0x01. In the least significant byte, the 4 most significant bits represent each button. Bit 7 is the blue down button, bit 6 is the blue up button, bit 5 is the red down button, bit 4 is the red up button. Beware that when no buttons are pressed, bit 7 is set (value == 384). You can test that bits 0-3 are all 0 to check this.

Example:

if ((value & 0x0F) == 0) {
    // no buttons are pressed
} else {
    if (value & 0x80)
        // blue down button is pressed
    if (value & 0x40)
        // blue up button is pressed
    if (value & 0x20)
        // red down button is pressed
    if (value & 0x10)
        // red up button is pressed
}

Bits 0-3 seem to be some sort of checksum or parity check. Bit 0 = bit 4, bit 1 = ~(bit 5), bit 2 = ~(bit 6), bit 3 = 0 if bits 0-2 are even or 1 if bits 0-2 are odd.

Also, when the beacon mode is active or for about 1 second after any button is released the value is 262.

This mode only works with the remote on channel 1.

[34]	`IR-S-ALT` mode is not usable. When switching to this mode, the sensor quits responding to the keep-alive messages and the sensor resets.

LEGO WeDo USB Hub¶

General Info¶

Driver Name	`wedo-hub`
Website	education.lego.com
Connection Type	USB
Number of Modes	1

Modes¶

Mode Description Units Decimals Num. Values Values

HUB

Hub status

none

0

2

value0: Status bits [35]

value1: Voltage (millivolts)

Commands¶

Command	Description
`OUT-OFF`	Turns off the outputs of the ports.
`OUT-ON`	Turns on the outputs of the ports.
`CLEAR-ERR`	Clears error.

Notes¶

[35]

Status Bits:

Bit	Description
0	Echo
1
2
3
4
5
6	High Power
7	Outputs Off

LEGO WeDo Motion Sensor¶

General Info¶

Driver Name	`wedo-motion`
Website	education.lego.com
Connection Type	Wedo/Analog
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`PROX`	Proximity	`pct` (percent)	0	1	`value0`: Proximity (0 - 100)
`RAW`	Raw analog value	none	0	1	`value0`: Proximity (0 - 255)

Commands¶

This sensor does not support commands.

LEGO WeDo Tilt Sensor¶

General Info¶

Driver Name	`wedo-tilt`
Website	education.lego.com
Connection Type	Wedo/Analog
Number of Modes	3

Modes¶

Mode Description Units Decimals Num. Values Values

TILT Tilt status none 0 1 value0: Tilt (0 to 5) [36]

TILT-AXIS

Tilt around 2 separate axes

none

0

3

value0: Tilt Left/Right (-1/0/1) [37]

value1: Tilt Back/Front (-1/0/1) [37]

value2: Tilt value valid (0/1) [37]

RAW Raw analog value none 0 1 value0: Tilt (0 - 255) [38]

Commands¶

This sensor does not support commands.

Notes¶

[36]

Tilt values:

Value	Description
0	Level
1	Front
2	Back
3	Left
4	Right
5	Unknown

[37]

(1, 2, 3)

Axis values:

Value0	Value1	Value2	Description
0	0	1	Level
0	1	1	Front
0	-1	1	Back
-1	0	1	Left
1	0	1	Right
0	0	0	Unknown

[38]

Raw values:

Value	Description
0	Unknown
< 48	Back
< 99	Right
< 153	Level
< 204	Front
< 255	Left

LEGO Energy Display¶

General Info¶

Driver Name	`lego-power-storage`
Website	education.lego.com
Connection Type	NXT/I2C
Default Address	0x02
Vendor ID	`LEGO`
Product ID	`Store`
Number of Modes	8

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`IN-VOLT`	Input Voltage	`V` (volts)	3	1	`value0`: Voltage (0 to 10000)
`IN-AMP`	Input Current	`A` (amps)	3	1	`value0`: Current (0 to 10000)
`OUT-VOLT`	Output Voltage	`V` (volts)	3	1	`value0`: Voltage (0 to 10000)
`OUT-AMP`	Output Current	`A` (amps)	3	1	`value0`: Current (0 to 10000)
`JOULE`	Energy	`J` (Joules)	0	1	`value0`: Energy (0 to 100)
`IN-WATT`	Input Power	`W` (Watts)	3	1	`value0`: Power (0 to 10000)
`OUT-WATT`	Output Power	`W` (Watts)	3	1	`value0`: Power (0 to 10000)
`ALL`	All	none	3	7	`value0`: Input Voltage (0 to 10000) `value1`: Input Current (0 to 10000) `value2`: Output Voltage (0 to 10000) `value3`: Output Current (0 to 10000) `value4`: Energy (0 to 100) `value5`: Input Power (0 to 10000) `value6`: Output Power (0 to 10000)

Commands¶

This sensor does not support commands.

LEGO NXT Temperature Sensor¶

General Info¶

Driver Name	`lego-nxt-temp`
Website	education.lego.com
Connection Type	NXT/I2C
Default Address	0x4C
Vendor ID	`LEGO`
Product ID	`Temp.`
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`NXT-TEMP-C`	Continuous measurement	`C` (°C)	1	1	`value0`: Temperature (-550 to 1280)
`NXT-TEMP-F`	Continuous measurement	`F` (°F)	1	1	`value0`: Temperature (-670 to 2624)

Commands¶

This sensor does not support commands.

LEGO NXT Touch Sensor¶

General Info¶

Driver Name	`lego-nxt-touch`
Website	shop.lego.com
Connection Type	NXT/Analog
Number of Modes	1

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`TOUCH`	Button state	none	0	1	`value0`: State (0 or 1) [39]

Commands¶

This sensor does not support commands.

Notes¶

[39]

Values:

Value	Description
0	Released
1	Pressed

LEGO NXT Light Sensor¶

General Info¶

Driver Name	`lego-nxt-light`
Website	shop.lego.com
Connection Type	NXT/Analog
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`REFLECT`	Reflected light - LED on	`pct` (percent)	1	1	`value0`: Reflected light intensity (0 to 1000)
`AMBIENT`	Ambient light - LED off	`pct` (percent)	1	1	`value0`: Ambient light intensity (0 to 1000)

Commands¶

This sensor does not support commands.

LEGO NXT Sound Sensor¶

General Info¶

Driver Name	`lego-nxt-sound`
Website	shop.lego.com
Connection Type	NXT/Analog
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`DB`	Sound pressure level - Flat weighting	`pct` (percent)	1	1	`value0`: Sound pressure level (0 to 1000)
`DBA`	Sound pressure level - A weighting	`pct` (percent)	1	1	`value0`: Sound pressure level (0 to 1000)

Commands¶

This sensor does not support commands.

LEGO NXT Ultrasonic Sensor¶

General Info¶

Driver Name	`lego-nxt-us`
Website	shop.lego.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`LEGO`
Product ID	`Sonar`
Number of Modes	5

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`US-DIST-CM`	Continuous measurement	`cm` (centimeters)	0	1	`value0`: Distance (0 to 255)
`US-DIST-IN`	Continuous measurement	`in` (inches)	1	1	`value0`: Distance (0 to 1000)
`US-SI-CM`	Single measurement	`cm` (centimeters)	0	1	`value0`: Distance (0 to 255) [40]
`US-SI-IN`	Single measurement	`in` (inches)	1	1	`value0`: Distance (0 to 1000) [40]
`US-LISTEN`	Listen	none	0	1	`value0`: Presence (0 or 1) [41]

Commands¶

This sensor does not support commands.

Notes¶

[40]	(1, 2) The value is read when the mode is set and does not change - even when polling is enabled. To read a new value, set the mode again (e.g. `echo US-SI-CM > mode`).

[41]	A value of 1 indicates that another ultrasonic sensor has been detected. A 1 can also be triggered by a loud noise such as clapping.

Microinfinity Digital Gyroscope And Accelerometer¶

General Info¶

Driver Name	`mi-xg1300l`
Website	www.minfinity.com
Connection Type	NXT/I2C
Default Address	0x01
Vendor ID	`mnfinity` [42]
Product ID	`XG1300L` [42]
Number of Modes	4

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`ANGLE`	Angle	`deg` (degrees)	2	1	`value0`: Z-axis angle (-18000 to 18000)
`SPEED`	Rotational speed	`d/s` (degrees per second)	2	1	`value0`: Z-axis rotational speed
`ACCEL`	Acceleration in X, Y, Z axis	`g` (Standard gravity) [43]	3	3	`value0`: Acceleration in X axis `value1`: Acceleration in Y axis `value2`: Acceleration in Z axis
`ALL`	All values	none	0	5	`value0`: Z-axis angle (-18000 to 18000) [44] `value1`: Z-axis rotational speed [45] `value2`: X-axis acceleration [46] `value3`: Y-axis acceleration [46] `value4`: Z-axis acceleration [46]

Commands¶

Command	Description
`RESET` [47]	Reset device
`ACCEL-2G`	Set accelerometer scaling to 2G
`ACCEL-4G`	Set accelerometer scaling to 4G
`ACCEL-8G`	Set accelerometer scaling to 8G

Notes¶

[42]

(1, 2)

CruizCore XG1300L doesn’t follow LEGO guidelines by returning vendor, product and firmware version values. As a result, this sensor can’t be automatically detected. Until we find another way to identify the sensor, the driver has to be loaded manually.

Register I2C device:

echo mi-xg1300l 0x01 > /sys/class/lego-port/port<N>/set_device

[43]	$1 g \approx 9.81 m/s^2$

[44]	Two decimal places

[45]	Two decimal places

[46]	(1, 2, 3) Three decimal places, range as was set by last command

[47]	Recalculate bias drift, reset accumulated angle, set accelerometer scaling factor to 2G, this has to be done with sensor not moving and is strongly recommended to be called manually before work.

mindsensors.com Gyro, MultiSensitivity Accelerometer and Compass¶

General Info¶

Driver Name	`ms-absolute-imu`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x11 [48]
Vendor ID	`mndsnsrs`
Product ID	`AbsIMU`
Number of Modes	6

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`TILT`	Tilt	`deg` (degrees)	0	3	`value0`: X-axis angle (0 to 180) `value1`: Y-axis angle (0 to 180) `value2`: Z-axis angle (0 to 180)
`ACCEL` [49]	Acceleration	`g` (Standard gravity) [50]	3	3	`value0`: X-axis acceleration `value1`: Y-axis acceleration `value2`: Z-axis acceleration
`COMPASS` [51]	Compass	`deg` (degrees)	0	1	`value0`: Heading (0 to 360)
`MAG` [51]	Magnetic field	none	0	3	`value0`: X-axis magnetic field `value1`: Y-axis magnetic field `value2`: Z-axis magnetic field
`GYRO` [52]	Gyro	`d/s` (degrees per second)	1	3	`value0`: X-axis rotational speed `value1`: Y-axis rotational speed `value2`: Z-axis rotational speed
`ALL` [53]	All data	none	0	23	`value0`: `value1`: `value2`: `value3`: `value4`: `value5`: `value6`: `value7`: `value8`: `value9`: `value10`: `value11`: `value12`: `value13`: `value14`: `value15`: `value16`: `value17`: `value18`: `value19`: `value20`: `value21`: `value22`:

Commands¶

Command	Description
`BEGIN-COMP-CAL`	Begin compass calibration
`END-COMP-CAL`	End compass calibration
`ACCEL-2G` [54]	Change accelerometer sensitivity to 2G and gyro sensitivity to 250 deg/sec
`ACCEL-4G` [54]	Change accelerometer sensitivity to 4G and gyro sensitivity to 500 deg/sec
`ACCEL-8G` [54]	Change accelerometer sensitivity to 8G and gyro sensitivity to 2000 deg/sec
`ACCEL-16G` [54]	Change accelerometer sensitivity to 16G and gyro sensitivity to 2000 deg/sec

Notes¶

[48]	The address is programmable. See manufacturer documentation for more information.

[49]	Only returns data from models with an accelerometer (AbsoluteIMU-AC / AbsoluteIMU-A).

[50]	Standard gravity (g) is defined as $1 g = 9.81 m/s^2$

[51]	(1, 2) Only returns data from models with a compass (AbsoluteIMU-C / AbsoluteIMU-AC / AbsoluteIMU-ACG).

[52]	Only returns data from models with a gyro (AbsoluteIMU-ACG).

[53]	Reads all data from the sensor. Use `bin_data` attribute to read values. Some values will not be scaled. See manufacturer docs for more info.

[54]	(1, 2, 3, 4) Wait 50 msec after sending command for sensor to reconfigure itself.

mindsensors.com GlideWheel-AS¶

General Info¶

Driver Name	`ms-angle`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x18
Vendor ID	`mndsnsrs`
Product ID	`AngSens`
Number of Modes	4

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`ANGLE`	Angle	`deg` (degrees)	0	1	`value0`: Angle
`ANGLE2`	High-precision angle	`deg` (degrees)	1	1	`value0`: Angle
`SPEED`	Rotational Speed	`rpm` (revolutions per minute)	0	1	`value0`: Rotational Speed (-4000 to 4000)
`ALL`	All values	none	0	3	`value0`: Angle `value1`: Angle x2 [55] `value2`: Rotational Speed [56]

Commands¶

Command	Description
`RESET`	Reset angle values

Notes¶

[55]	Angle value times 2 (i.e. value of 10 = angle of 5 degrees). Allows for 0.5 degree precision.

[56]	Value needs to be converted to 16-bit signed integer. Example: `if (value2 > 32767) value2 = value2 - 65536`

mindsensors.com EV3 Sensor Multiplexer¶

General Info¶

Driver Name	`ms-ev3-smux`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x50, 0x51, 0x52 [57]
Vendor ID	`mndsnsrs`
Product ID	`Ev3SMux`
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`MUX` [59]	EV3 Sensor Multiplexer	none	0	0

Commands¶

This sensor does not support commands.

Notes¶

[57]	This sensor appears as three separate sensors, one for each channel on the sensor mux.

[58]	In addition to loading three [lego-sensor] devices for the sensor mux itself, three [lego-port] devices are added as well. These [ms-ev3-smux-port] devices must be used to manually specify the type of sensor that is attached to each port.

[59]	This mode does not do anything useful.

mindsensors.com Light Sensor Array¶

General Info¶

Driver Name	`ms-light-array`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x0A [60]
Vendor ID	`mndsnsrs`
Product ID	`LSArray`
Number of Modes	2

Modes¶

Mode Description Units Decimals Num. Values Values

CAL

Calibrated values

pct (percent)

0

8

value0: LED 0 (0 to 100)

value1: LED 1 (0 to 100)

value2: LED 2 (0 to 100)

value3: LED 3 (0 to 100)

value4: LED 4 (0 to 100)

value5: LED 5 (0 to 100)

value6: LED 6 (0 to 100)

value7: LED 7 (0 to 100)

RAW

Uncalibrated values

none

0

8

value0: LED 0 (0 to ???)

value1: LED 1 (0 to ???)

value2: LED 2 (0 to ???)

value3: LED 3 (0 to ???)

value4: LED 4 (0 to ???)

value5: LED 5 (0 to ???)

value6: LED 6 (0 to ???)

value7: LED 7 (0 to ???)

Commands¶

Command	Description
`CAL-WHITE`	Calibrate white
`CAL-BLACK`	Calibrate black
`SLEEP` [61]	Put sensor to sleep
`WAKE` [62]	Wake up the sensor
`60HZ`	Configures sensor for 60Hz electrical mains
`50HZ`	Configures sensor for 50Hz electrical mains
`UNIVERSAL`	Configures sensor for any (50/60Hz) electrical mains

Notes¶

[60]	The address is programmable. See manufacturer documentation for more information.

[61]	`poll_ms` must be set to 0 in order for sensor to sleep.

[62]	Will return an error (-ENXIO) if sensor is actually asleep. Completes successfully if sensor is already awake.

mindsensors.com Line Follower Sensor¶

General Info¶

Driver Name	`ms-line-leader`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x01 [63]
Vendor ID	`mndsnsrs`
Product ID	`LineLdr`
Number of Modes	4

Modes¶

Mode	Description	Units	Num. Values	Values
`PID`	Line Follower	`pct` (percent)	1	`value0`: Steering (-100 to 100) [64]
`PID-ALL`	Line Follower - all values	none	3	`value0`: Steering (-100 to 100) [64] `value1`: Average (0 to 80) [65] `value2`: Result (as bits) [66]
`CAL`	Calibrated values	`pct` (percent)	8	`value0`: LED 0 (0 to 100) `value1`: LED 1 (0 to 100) `value2`: LED 2 (0 to 100) `value3`: LED 3 (0 to 100) `value4`: LED 4 (0 to 100) `value5`: LED 5 (0 to 100) `value6`: LED 6 (0 to 100) `value7`: LED 7 (0 to 100)
`RAW`	Uncalibrated values	none	8	`value0`: LED 0 (0 to ???) `value1`: LED 1 (0 to ???) `value2`: LED 2 (0 to ???) `value3`: LED 3 (0 to ???) `value4`: LED 4 (0 to ???) `value5`: LED 5 (0 to ???) `value6`: LED 6 (0 to ???) `value7`: LED 7 (0 to ???)

Commands¶

Command	Description
`CAL-WHITE`	Calibrate white
`CAL-BLACK`	Calibrate black
`SLEEP` [67]	Put sensor to sleep
`WAKE` [68]	Wake up the sensor
`INV-COL`	Color inversion (White line on a black background)
`RST-COL`	Reset Color inversion (black line on a white background).
`SNAP` [69]	Take a snapshot.
`60HZ`	Configures sensor for 60Hz electrical mains
`50HZ`	Configures sensor for 50Hz electrical mains
`UNIVERSAL`	Configures sensor for any (50/60Hz) electrical mains

Notes¶

[63]	The address is programmable. See manufacturer documentation for more information.

[64]	(1, 2) “Steering” is the power value returned by the sensor to correct your course. Add this value to your left motor and subtract from right motor.

[65]	“Average” is the weighted average of the sensor reading. The average is a weighted average of the bits set to 1 based on the position. i.e. left most bit has weight of 10, second bit has* weight of 20.

[66]	“Result” is a byte value of the sensor reading. Each bit corresponding to the sensor where the line is seen is set to 1, or else the bit is zero.

[67]	`poll_ms` must be set to 0 in order for sensor to sleep.

[68]	Will return an error (-ENXIO) if sensor is actually asleep. Completes successfully if sensor is already awake.

[69]

The “SNAP” command looks at the line under the sensor and stores the width and position of the line in sensor’s memory. Subsequently, sensor will use these characteristics of line to track it. This command inverts the colors if it sees a white line on black background. (PID parameters are not affected.)

mindsensors.com Vision Subsystem v4 for NXT or EV3¶

General Info¶

Driver Name	`ms-nxtcam`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x01 [70]
Vendor ID	`mndsnsrs`
Product ID	`NXTCAM`
Number of Modes	1

Modes¶

Mode Description Units Decimals Num. Values Values

TRACK [71]

Tracking

none

0

6

value0: Object count

value1: Color index

value2: X upper left

value3: Y upper left

value4: X lower right

value5: Y lower right

Commands¶

Command	Description
`TRACK-ON`	Enable tracking
`TRACK-OFF`	Disable tracking
`TRACK-OBJ`	Set to object tracking mode
`TRACK-LINE`	Set to line tracking mode
`SORT-SIZE`	Sort by size
`SORT-COL`	Sort by color

Notes¶

[70]	The address is programmable. See manufacturer documentation for more information.

[71] This driver only allows for tracking a single object. To track more than one object and for other more advanced uses, you can disable this driver by setting poll_ms to 0 and using the direct attribute to directly read and write I2C messages. See Appendix C: I2C Devices and the manufacturers documentation for more information.

mindsensors.com Multiplexer for NXT/EV3 Motors¶

General Info¶

Driver Name	`ms-nxtmmx`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x03 [72]
Vendor ID	`mndsnsrs`
Product ID	`NxTMMX`
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`STATUS`	Status	`V` (volts)	3	1	`value0`: Battery voltage
`STATUS-OLD` [74]	Status (for older firmware versions)	`V` (volts)	3	1	`value0`: Battery voltage

Commands¶

This sensor does not support commands.

Notes¶

[72]	The address is programmable. See manufacturer documentation for more information.

[73] The NxtMMX driver also loads two [tacho-motor] class devices. Use the tacho-motor class devices to actually control the motors. You can identify the motors by the address attribute. It will be in<X>:i2c<Y>:mux<Z> where <X> is 1-4, <Y> is 3 (unless you changed the address) and <Z> is 1 or 2 (matches M1 or M2 printed on the NxtMMX).

[74]	The I2C register for battery voltage was changed for EV3 compatibility. If the `STATUS` mode does not seem to work, try this mode instead.

mindsensors.com 8-channel Servo Controller¶

General Info¶

Driver Name	`ms-8ch-servo`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x58 [75]
Vendor ID	`mndsnsrs`
Product ID	`NXTServo`
Number of Modes	2

Modes¶

Mode	Description	Units	Decimals	Num. Values	Values
`V3`	EV3 Compatible	`V` (volts)	3	1	`value0`: Battery voltage (0 to 9400) [77]
`OLD` [78]	Older versions	`V` (volts)	3	1	`value0`: Battery voltage (0 to 9400) [77]

Commands¶

This sensor does not support commands.

Notes¶

[75]	The address is programmable. See manufacturer documentation for more information.

[76] The ms-8ch-servo driver loads separate servo motor devices (one for each of the 8 channels) in addition to the The lego-sensor Subsytem device. See the servo-motor Subsystem for more information. The servo-motor class address attribute will return in<X>:i2c<Y>:sv<Z> where <X> is the input port the servo controller is connected to, <Y> is the address and <Z> is the channel as indicated on the servo controller itself.

[77]	(1, 2) The current voltage scaling is based on the manufacturers documentation, however it seems to be low. If you are seeing this too, please open an issue on GitHub and we will change the scaling.

[78]	Older versions of this sensor have the battery voltage at a different address. If the default mode does not return a value, try this mode.

mindsensors.com Sensor building kit for NXT with PCF8574 IC¶

General Info¶

Driver Name	`pcf8574`
Website	mindsensors.com
Connection Type	Other/I2C
Default Address	0x38 [79]

Notes¶

[79]	Valid addresses are 0x38..0x3F (configurable via input pins)

[80]

Sample usage:

Register I2C device:

echo pcf8574 0x38 > /sys/bus/i2c/devices/i2c-<port+2>/new_device

Finding device class node and initializing:

for chip in $(find /sys/class/gpio -name gpiochip*)
do
    if [[ "$(cat $chip/label)" == "pcf8547" ]]
    then
        base=$(cat $chip/base)
        # Pins are active low
        for i in {0..7}
        do
            gpio=$(($base + $i))
            echo $gpio > /sys/class/gpio/export
            # gpios on this chip are active low
            echo 1 > /sys/class/gpio/gpio$gpio/active_low
            # initialize direction here
        done
        # do whatever with the gpios
    fi
done

mindsensors.com Sensor building kit for NXT with PCF8591 IC¶

General Info¶

Driver Name	`pcf8591`
Website	mindsensors.com
Connection Type	Other/I2C
Default Address	0x48 [81]

Notes¶

[81]	Valid addresses are 0x48..0x4F (configurable via input pins)

[82]	Sample usage: Register I2C device: echo pcf8591 0x48 > /sys/bus/i2c/devices/i2c-<port+2>/new_device Finding device class node: for chip in $(find /sys/class/hwmon -name hwmon*) do if [[ "$(cat $chip/device/name)" == "pcf8591" ]] then # do whatever fi done

mindsensors.com Digital Pneumatic Pressure Sensor¶

General Info¶

Driver Name	`ms-pps58-nx`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x0C
Vendor ID	`mndsnsrs`
Product ID	`PPS58`
Number of Modes	7

Modes¶

Mode	Description	Units	Num. Values	Values
`RAW`	Raw sensor value	`Pa`	1	`value0`: Pressure (0 to 400,000 Pa)
`ABS-PSI`	Absolute pressure (PSI)	`PSI` (Pounds per square inch)	1	`value0`: Pressure (0 to 58 PSI)
`ABS-MBAR`	Absolute pressure (millibar)	`mbar` (millibar)	1	`value0`: Pressure (0 to 4000 millibar)
`ABS-KPA`	Absolute pressure (kPa)	`kPa` (kilopascals)	1	`value0`: Pressure (0 to 400 kPa)
`REL-PSI`	Gauge pressure (PSI)	`PSI` (Pounds per square inch)	1	`value0`: Pressure (0 to 58 PSI minus the reference pressure)
`REL-MBAR`	Gauge pressure (millibar)	`mbar` (millibar)	1	`value0`: Pressure (0 to 4000 millibar minus the reference pressure)
`REL-KPA`	Gauge pressure (kPa)	`kPa` (kilopascals)	1	`value0`: Pressure (0 to 400 kPa minus the reference pressure)

Commands¶

Command	Description
`ZERO` [83]	Change Reference pressure to current absolute pressure.

Notes¶

[83]	The reference pressure is used to calculate the gauge pressure. Therefore, this command only affects the `REL-*` modes.

mindsensors.com Pixy Adapter for MINDSTORMS EV3 or NXT¶

General Info¶

Driver Name	`ms-pixy-adapter`
Website	www.mindsensors.com
Connection Type	NXT/I2C
Default Address	0x01 [84]
Vendor ID	`mndsnsrs`
Product ID	`PixyAdpt`
Number of Modes	1

Modes¶

Mode Description Units Decimals Num. Values Values

TRACK [85]

Tracking

none

0

6

value0: Object count

value1: Color index

value2: X upper left

value3: Y upper left

value4: X lower right

value5: Y lower right

Commands¶

Command	Description
`SORT-SIZE`	Sort by size
`SORT-COL`	Sort by color

Notes¶

[84]	The address is programmable. See manufacturer documentation for more information.

[85] This driver only allows for tracking a single object. To track more than one object and for other more advanced uses, you can disable this driver by setting poll_ms to 0 and using the direct attribute to directly read and write I2C messages. See the [Using I2C Sensors] page and the manufacturers documentation for more information.

mindsensors.com Realtime Clock for NXT¶

General Info¶

Driver Name	`ds1307`
Website	mindsensors.com
Connection Type	Other/I2C
Default Address	0x68

Notes¶

[86]	Sample usage: Register I2C device: echo ds1307 0x68 > /sys/bus/i2c/devices/i2c-<port+2>/new_device Finding device class node: for chip in $(find /sys/class/rtc -name rtc*) do if [[ "$(cat $chip/name)" == "ds1307" ]] then # do whatever fi done

mindsensors.com Touch Sensor Multiplexer for NXT & EV3¶

General Info¶

Driver Name	`ms-nxt-touch-mux`
Website	mindsensors.com
Connection Type	NXT/Analog
Number of Modes	1

Modes¶

Mode Description Units Decimals Num. Values Values

TOUCH-MUX

Touch sensors

none

0

3

value0: Sensor T1 state [87]

value1: Sensor T2 state [87]

value2: Sensor T3 state [87]

Commands¶

This sensor does not support commands.

Notes¶

[87]

(1, 2, 3)

Values:

Value	Description
0	Released
1	Pressed

Appendix B: Motor Data¶

This page contains sensor-specific data for each type of supported motor.

Actuonix L12 EV3 100mm¶

General Info¶

Driver Name	`act-l12-ev3-100`
Website	www.actuonix.com
Connection Type	ev3

Actuonix L12 EV3 50mm¶

General Info¶

Driver Name	`act-l12-ev3-50`
Website	www.actuonix.com
Connection Type	ev3

LEGO Motor 9V Mini-motor, newer lighter weight¶

General Info¶

Driver Name	`lego-43362`
Website	rebrickable.com
Connection Type	rcx

LEGO EV3 Large Servo Motor¶

General Info¶

Driver Name	`lego-ev3-l-motor`
Website	shop.lego.com
Connection Type	ev3

LEGO EV3 Medium Servo Motor¶

General Info¶

Driver Name	`lego-ev3-m-motor`
Website	shop.lego.com
Connection Type	ev3

LEGO Technic Motor 9V Geared ¶

General Info¶

Driver Name	`lego-47154`
Website	rebrickable.com
Connection Type	rcx

LEGO Motor 9V Micromotor¶

General Info¶

Driver Name	`lego-70823`
Website	rebrickable.com
Connection Type	rcx

LEGO Motor 9V Mini-motor, older heavier weight¶

General Info¶

Driver Name	`lego-71427`
Website	rebrickable.com
Connection Type	rcx

LEGO Technic Motor 9V¶

General Info¶

Driver Name	`lego-74569`
Website	rebrickable.com
Connection Type	rcx

LEGO Power Functions Train Motor¶

General Info¶

Driver Name	`lego-88002`
Website	shop.lego.com
Connection Type	rcx

LEGO Power Functions L-Motor¶

General Info¶

Driver Name	`lego-88003`
Website	shop.lego.com
Connection Type	rcx

LEGO Power Functions Servo Motor¶

General Info¶

Driver Name	`lego-88004`
Website	shop.lego.com
Connection Type	rcx

LEGO Power Functions XL-Motor¶

General Info¶

Driver Name	`lego-8882`
Website	shop.lego.com
Connection Type	rcx

LEGO Power Functions M-Motor¶

General Info¶

Driver Name	`lego-8883`
Website	shop.lego.com
Connection Type	rcx

LEGO Power Functions E-Motor¶

General Info¶

Driver Name	`lego-9670`
Website	education.lego.com
Connection Type	rcx

LEGO NXT (Interactive Servo) Motor¶

General Info¶

Driver Name	`lego-nxt-motor`
Website	shop.lego.com
Connection Type	ev3

Appendix C: I2C Devices¶

The I2C standards only specify how data is sent from device to device. It does not specify the layout of the registers of a device. LEGO, however, has guidelines for 3rd party manufactures so that they can provide sensors with a (fairly) uniform register layout.

We call sensors that were designed following LEGO’s guidelines NXT/I2C sensors. This common register layout lets us autodetect the type of sensor and proves access to the sensor via the lego-sensor class.

We refer to sensors that do not conform to LEGO’s specifications as Other/I2C sensors. There are so many types of I2C chips in the wild that are already supported on Linux that we do not attempt to autodetect them. To use them, we just need to find a compatible driver and manually load it.

This page discusses both types of I2C sensors.

Addressing¶

I2C uses a 7-bit addressing scheme (there is also 10-bit addressing but it is not implemented in the ev3dev I2C driver). When sending an address over the bus, the address is shifted to the left 1 bit and the least significant bit is used to indicate read or write.

Note

The I2C address that is used in ev3dev is different from the other EV3/NXT programming languages/environments. This means the address in your sensors’ documentation is probably not the address that you need for ev3dev! In ev3dev (and Linux in general), we used the unshifted 7-bit address.

I2C addresses 0x01 through 0x07 (unshifted) are reserved for special use by the I2C specifications. However, these addresses are used by some sensors anyway (most notably the NXT Ultrasonic sensor). The ev3dev kernel has been patched to allow these to work, but some userspace tools will not work with devices at these addresses. For example, we distribute a patched version of the i2c-tools package to work around this.

There is a table of I2C addresses at the end of the page.

Using NXT/I2C Sensors¶

See the page on the lego-sensor class for general usage. This page only covers the I2C specifics.

Polling¶

When we say “polled”, we just mean that the EV3 brick initiates a read command to read data from the sensor. The data that is read depends on the current mode that is selected. You can change the polling rate using the poll_ms attribute (of the lego-sensor device). You can also disable polling by setting poll_ms to 0. When polling is disabled, you can initiate a data read by setting the mode again. By default, NXT/I2C sensors are polled every 100 milliseconds. The default value can be changed via a module parameter.

Direct Reading and Writing of the Sensor¶

Warning

Be very careful when reading from or writing to your sensors. It is theoretically possible to break them if you read or write to the wrong register.

In most cases, setting the mode of a sensor will write the proper data if necessary, so you don’t actually need to write data using this method. However, it is possible to write arbitrary data to I2C sensors using the direct attribute. Use seek to specify the register to read or write from and always specify the number of bytes to read or write.

Example: Reading the white calibration data from the mindsensors.com Light Sensor Array. This reads 8 bytes from register 0x5A.

$ hd -s $(( 0x5A )) -n 8 direct

Example: Sending a “calibrate white” command to the mindsensor.com Light Sensor Array. This just writes the ascii character W to register 0x41.

$ echo -e -n "W" | dd bs=1 of=direct seek=$(( 0x41 ))

Manually Loading Devices¶

If you have autodetection disabled (e.g. using the other-i2c mode of a port) or if you have managed to change the I2C address of your sensor to something other than the default or you are using something that is not even a LEGO compatible sensor, you will have to manually load a device in order to be able to use your sensor. We just have to tell the I2C adapter which driver to use and the address of the device.

The I2C adapter device nodes are at /sys/bus/i2c/devices/i2c-N where N is the number of the input port plus 2. To load a device, we write to the new_device attribute. NOTE: These nodes only exist when you have an I2C sensor plugged into an input port or the port was manually set to an I2C mode.

Example:

# echo nxt-i2c-sensor 0x0B > /sys/bus/i2c/devices/i2c-5/new_device

Using Other/I2C Sensors¶

As we already discussed, Other/I2C sensors generally have an existing Linux driver that you can use. This means that each sensor will work a bit differently. You can load a device just like for manually loading an NXT/I2C device, except we use a different driver name. You can find the names of drivers here.

Example: Using the mindsensors.com Realtime Clock Sensor on input port 2.

$ echo ds1307 0x68 > /sys/bus/i2c/devices/i2c-4/new_device
$ dmesg | tail
...
i2c-legoev3 i2c-legoev3.4: registered on input port 2
i2c i2c-4: new_device: Instantiated device ds1307 at 0x68
rtc-ds1307 4-0068: SET TIME!
rtc-ds1307 4-0068: rtc core: registered ds1307 as rtc1
rtc-ds1307 4-0068: 56 bytes nvram
$ cd /sys/class/rtc
$ ls
rtc0    rtc1
$ cd rtc1
$ ls
date  device   max_user_freq  since_epoch  time
dev   hctosys  name           subsystem    uevent

Now, I just need to figure out what to do with TWO realtime clocks!

Direct I2C Communication (Going Driverless)¶

You actually don’t need a driver to use your I2C sensors. Drivers do make it much safer and easier, but if you really want full control, it is yours for the taking. There are symlinks for each I2C adapter to make finding them easy.

$ ls /dev/i2c-in*
/dev/i2c-in2  /dev/i2c-in3

Note

The symlinks and the underlying I2C device are only present when an I2C sensor is plugged into a port. Also, if a driver is loaded for a particular I2C device, you will get an error that it is in use. You should disable probing in the nxt-i2c-sensor module (or blacklist the driver in /etc/modprobe.d).

You can use the i2c-tools package or an I2C library in your programming language of choice to communicate with I2C devices this way. You don’t want to do this if a device is already loaded so you will want to disable autodetection first if the sensor is the autodetected type. Beware that many sensors, including the NXT Ultrasonic Sensor use an address of 0x01, which is illegal according to the I2C standards. i2c-tools and any library that does some error checking may prevent you from accessing the sensor. In ev3dev-stretch, the i2c-tools package has been patched to work around this.

Practical examples¶

Changing the Polling Rate¶

Using the NXT Ultrasonic Sensor:

$ cat poll_ms
100
$ while true; do cat value0; done
22
23
26
27
30
25
...
22
24
26
26
22
22
^C
$ echo 1000 > poll_ms
$ while true; do cat value0; done
22
22
22
22
22
22
22
25
25
25
25
25
25
25
25
...
^C
$ echo 0 > poll_ms
$ cat value0 # value0 will be last value measured before polling stopped
23
$ cat value0 # move the sensor and try again
23
$ cat mode
[NXT-US-CM] NXT-US-IN NXT-US-SI-CM NXT-US-SI-IN NXT-US-LIST
$ echo NXT-US-CM > mode # reads data
$ cat value0
29
$ cat value0 # move the sensor and try again
29

^C means you have to press CTRL+C to make the loop stop.

Sample /etc/modprobe.d/nxt-i2c-sensor.conf¶

# Module configuration for nxt-i2c-sensor

# Uncomment this line to disable polling
#options nxt-i2c-sensor default_poll_ms=0

# Uncomment this line to disable autodetection
#options nxt-i2c-sensor allow_autodetect=N

How to find the I2C adapter node without adding 2¶

$ IN2_I2C_ADAP=$(udevadm info -q path -n /dev/i2c-in2)"/../.."
$ echo $IN2_I2C_ADAP
/devices/platform/legoev3-ports/in2/in2:nxt-i2c-host/i2c-legoev3.4/i2c-4/i2c-dev/i2c-4/../..

Using i2c-tools¶

With the mindsensors.com Realtime Clock Sensor on input port 2:

& i2cdump 4 0x68
No size specified (using byte-data access)
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-4, address 0x68, mode byte
Continue? [Y/n] y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00: 11 35 00 01 01 01 00 03 50 71 48 60 f5 01 6b 0c    ?5.???.?PqH`??k?
10: 78 e3 2d 4e 92 6e c7 69 25 61 6b 5b 04 34 15 05    x?-N?n?i%ak[?4??
20: cc 3e 4e 4b 41 8a 59 09 1b f3 1a 2a 7c 47 a7 90    ?>NKA?Y????*|G??
30: 20 6a 95 7a 3b da 5b de 73 31 a2 3a 6e 59 ed f8     j?z;?[?s1?:nY??
40: 11 35 00 01 01 01 00 03 50 71 48 60 f5 01 6b 0c    ?5.???.?PqH`??k?
50: 78 e3 2d 4e 92 6e c7 69 25 61 6b 5b 04 34 15 05    x?-N?n?i%ak[?4??
60: cc 3e 4e 4b 41 8a 59 09 1b f3 1a 2a 7c 47 a7 90    ?>NKA?Y????*|G??
70: 20 6a 95 7a 3b da 5b de 73 31 a2 3a 6e 59 ed f8     j?z;?[?s1?:nY??
80: 11 35 00 01 01 01 00 03 50 71 48 60 f5 01 6b 0c    ?5.???.?PqH`??k?
90: 78 e3 2d 4e 92 6e c7 69 25 61 6b 5b 04 34 15 05    x?-N?n?i%ak[?4??
a0: cc 3e 4e 4b 41 8a 59 09 1b f3 1a 2a 7c 47 a7 90    ?>NKA?Y????*|G??
b0: 20 6a 95 7a 3b da 5b de 73 31 a2 3a 6e 59 ed f8     j?z;?[?s1?:nY??
c0: 12 35 00 01 01 01 00 03 50 71 48 60 f5 01 6b 0c    ?5.???.?PqH`??k?
d0: 78 e3 2d 4e 92 6e c7 69 25 61 6b 5b 04 34 15 05    x?-N?n?i%ak[?4??
e0: cc 3e 4e 4b 41 8a 59 09 1b f3 1a 2a 7c 47 a7 90    ?>NKA?Y????*|G??
f0: 20 6a 95 7a 3b da 5b de 73 31 a2 3a 6e 59 ed f8     j?z;?[?s1?:nY??
$ i2cget -y 4 0x68 0x01 | sed s/0x// # read minutes
35
$ i2cset -y 4 0x68 0x08 0x46 0x72 0x65 0x65 0x20 0x72 0x61 0x6d 0x20 0x73 0x70 0x61 0x63 0x65 0x21 i
$ i2cdump -y -r 0x08-0x16 4 0x68
No size specified (using byte-data access)
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f    0123456789abcdef
00:                         46 72 65 65 20 72 61 6d            Free ram
10: 20 73 70 61 63 65 21                                space!

Useful Info¶

Table of I2C addresses¶
Shifted Address (write/read)	Unshifted Address (hex (dec))	Notes
0x00/0x01	0x00 (0)	I2C spec: General call address / START byte
0x02/0x03	0x01 (1)	LEGO NXT Ultrasonic and many 3rd party sensors I2C spec: CBUS address
0x04/0x05	0x02 (2)	LEGO Energy Storage I2C spec: Reserved for different bus format
0x06/0x07	0x03 (3)	mindsensors.com Motor Multiplexer I2C spec: Reserved for future purposes
0x08/0x09	0x04 (4)	I2C spec: Hs-mode master code
0x0A/0x0B	0x05 (5)	I2C spec: Hs-mode master code
0x0C/0x0D	0x06 (6)	I2C spec: Hs-mode master code
0x0E/0x0F	0x07 (7)	I2C spec: Hs-mode master code
0x10/0x11	0x08 (8)	Some HiTechnic sensors
0x12/0x13	0x09 (9)
0x14/0x15	0x0A (10)	mindsensors.com Light Sensor Array
0x16/0x17	0x0B (11)
0x18/0x19	0x0C (12)	mindsensors.com PPS58-Nx Pressure Sensor
0x1A/0x1B	0x0D (13)
0x1C/0x1D	0x0E (14)
0x1E/0x1F	0x0F (15)
0x20/0x21	0x10 (16)
0x22/0x23	0x11 (17)	mindsensors.com AbsoluteIMU Accel/Compass/Gyro
0x24/0x25	0x12 (18)
0x26/0x27	0x13 (19)
0x28/0x29	0x14 (20)
0x2A/0x2B	0x15 (21)
0x2C/0x2D	0x16 (22)
0x2E/0x2F	0x17 (23)
0x30/0x31	0x18 (24)	mindsensors.com GlideWheel-AS Angle Sensor
0x32/0x33	0x19 (25)
0x34/0x35	0x1A (26)
0x36/0x37	0x1B (27)
0x38/0x39	0x1C (28)
0x3A/0x3B	0x1D (29)
0x3C/0x3D	0x1E (30)
0x3E/0x3F	0x1F (31)
0x40/0x41	0x20 (32)
0x42/0x43	0x21 (33)
0x44/0x45	0x22 (34)
0x46/0x47	0x23 (35)
0x48/0x49	0x24 (06)
0x4A/0x4B	0x25 (37)
0x4C/0x4D	0x26 (38)
0x4E/0x4F	0x27 (39)
0x50/0x51	0x28 (40)
0x52/0x53	0x29 (41)
0x54/0x55	0x2A (32)
0x56/0x57	0x2B (43)
0x58/0x59	0x2C (44)
0x5A/0x5B	0x2D (45)
0x5C/0x5D	0x2E (46)
0x5E/0x5F	0x2F (47)
0x60/0x61	0x30 (48)
0x62/0x63	0x31 (49)
0x64/0x65	0x32 (50)
0x66/0x67	0x33 (51)
0x68/0x69	0x34 (52)
0x6A/0x6B	0x35 (53)
0x6C/0x6D	0x36 (54)
0x6E/0x6F	0x37 (55)
0x70/0x71	0x38 (56)	PCF8574 IC
0x72/0x73	0x39 (57)
0x74/0x75	0x3A (58)
0x76/0x77	0x3B (59)
0x78/0x79	0x3C (60)
0x7A/0x7B	0x3D (61)
0x7C/0x7D	0x3E (62)
0x7E/0x7F	0x3F (63)
0x80/0x81	0x40 (64)
0x82/0x83	0x41 (65)
0x84/0x85	0x42 (66)
0x86/0x87	0x43 (67)
0x88/0x89	0x44 (68)
0x8A/0x8B	0x45 (69)
0x8C/0x8D	0x46 (70)
0x8E/0x8F	0x47 (71)
0x90/0x91	0x48 (72)	PCF8591 IC
0x92/0x93	0x49 (73)
0x94/0x95	0x4A (74)
0x96/0x97	0x4B (75)
0x98/0x99	0x4C (76)	LEGO Temperature Sensor
0x9A/0x9B	0x4D (77)
0x9C/0x9D	0x4E (78)
0x9E/0x0F	0x4F (79)
0xA0/0xA1	0x50 (80)	mindsensors.com EV3 Sensor Multiplexer
0xA2/0xA3	0x51 (81)	mindsensors.com EV3 Sensor Multiplexer
0xA4/0xA5	0x52 (82)	mindsensors.com EV3 Sensor Multiplexer
0xA6/0xA7	0x53 (83)
0xA8/0xA9	0x54 (84)
0xAA/0xAB	0x55 (85)
0xAC/0xAD	0x56 (87)
0xAE/0xAF	0x57 (87)
0xB0/0xB1	0x58 (88)	mindsensors.com 8 Channel Servo Controller
0xB2/0xB3	0x59 (89)
0xB4/0xB5	0x5A (90)
0xB6/0xB7	0x5B (91)
0xB8/0xB9	0x5C (92)
0xBA/0xBB	0x5D (93)
0xBC/0xBD	0x5E (94)
0xBE/0xBF	0x5F (95)
0xC0/0xC1	0x60 (96)
0xC2/0xC3	0x61 (97)
0xC4/0xC5	0x62 (98)
0xC6/0xC7	0x63 (99)
0xC8/0xC9	0x64 (100)
0xCA/0xCB	0x65 (101)
0xCC/0xCD	0x66 (102)
0xCE/0xCF	0x67 (103)
0xD0/0xD1	0x68 (104)	mindsensors.com Realtime Clock
0xD2/0xD3	0x69 (105)
0xD4/0xD5	0x6A (106)
0xD6/0xD7	0x6B (107)
0xD8/0xD9	0x6C (108)
0xDA/0xDA	0x6D (109)
0xDC/0xDD	0x6E (110)
0xDE/0xDF	0x6F (111)
0xE0/0xE1	0x70 (112)
0xE2/0xE3	0x71 (113)
0xE4/0xE5	0x72 (114)
0xE6/0xE7	0x73 (115)
0xE8/0xE9	0x74 (116)
0xEA/0xEB	0x75 (117)
0xEC/0xED	0x76 (118)
0xEE/0xEF	0x77 (119)
0xF0/0xF1	0x78 (120)	I2C spec: 10-bit slave addressing
0xF2/0xF3	0x79 (121)	I2C spec: 10-bit slave addressing
0xF4/0xF5	0x7A (122)	I2C spec: 10-bit slave addressing
0xF6/0xF7	0x7B (123)	I2C spec: 10-bit slave addressing
0xF8/0xF9	0x7C (124)	I2C spec: Reserved for future purposes
0xFA/0xFB	0x7D (125)	I2C spec: Reserved for future purposes
0xFC/0xFD	0x7E (126)	I2C spec: Reserved for future purposes
0xFE/0xFF	0x7F (127)	I2C spec: Reserved for future purposes