ROS2 PIGPIO

A ROS2 package to use pigpio. This package is tested with Raspberry Pi 4 Model B with Ubuntu 20.04 LTS and foxy.

Install

1. Install pigpio following official instruction
2. Download this repository in <your ros2 workspace>/src
3. build this package with colcon build --packages-select ros2_pigpio

Preparing

sudo pigpiod # run pigpio daemon
cd <ros2_ws> # go to your ros2 workspace
source install/local_setup.bash # install local setup

Read Input Pin

To read inputted signal on GPIO-21 (PULL_UP), run the following command. A publisher will send read value of the pin.

ros2 run ros2_pigpio gpio_reader --ros-args --param pin:=21

You can set a input pin in pull-down with the below,

ros2 run ros2_pigpio gpio_reader --ros-args --param pin:=21 --param is_pull_up:=false

Write Output Pin

To write signal with GPIO-21, run a following command. A subscriber will wait for your inputs.

ros2 run ros2_pigpio gpio_writer --ros-args --param pin:=21 

When you submit a value to the subscriber, it write the signal on the pin. Write high signal:

ros2 topic pub --once gpio_output_21 std_msgs/msg/Bool '{data: true}'

Write low signal:

ros2 topic pub --once gpio_output_21 std_msgs/msg/Bool '{data: false}'

Write PWM Signals

To write pwm signal with GPIO-18, run a following command.

ros2 run ros2_pigpio gpio_pwm_writer  --ros-args --param pin:=18

A duty cycle is 0–255 which corresponded with 0%–100% Write 128 (50%) pwm signal:

ros2 topic pub --once gpio_pwm_18 std_msgs/msg/Int16 '{data: 128}'

Drive Wheels with DC-Motors (H-Bridge)

You can control DC motors with H-Bridge motor drivers.

To control the driver, run wheels.

ros2 run ros2_pigpio wheels 

wheels uses Maker Drive and GPIO-17, 18 and GPIO-27, 22 for Motor1 and 2, respectively in default settings.

You can drive wheels with publishing /wheels (topic).

Move Forward:

ros2 topic pub --once /wheels geometry_msgs/msg/Twist "{linear: {x: 1.0, y: 0.0, z: 0.0}, angular: {x: 1.0, y: 0.0, z: 0}}"

Move Backward

ros2 topic pub --once /wheels geometry_msgs/msg/Twist "{linear: {x: 1.0, y: 0.0, z: 0.0}, angular: {x: 1.0, y: 0.0, z: 0}}"

Turn Left

ros2 topic pub --once /wheels geometry_msgs/msg/Twist "{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 1.0}}"

Turn Right

ros2 topic pub --once /wheels geometry_msgs/msg/Twist "{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: -1.0}}"

Stop

ros2 topic pub --once /wheels geometry_msgs/msg/Twist "{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 0.0}}"