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Eren Eroğlu

Using ROS2 and Platform IO on ESP32

·396 words·2 mins
Table of Contents

Introduction
#

Requirements
#

Setting up a platformio project
#

Firstly create a platform io project for your board with

pio project init -b esp32dev -d (PROJECT DIRECTORY)

if you have a different board, you can check available boards with pio boards.

Adding microROS
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Firstly specifly your ROS distribution by adding following lines to platformio.ini located at the root of your project:

board_microros_distro = humble

Change the value humble for other distributions. Then add following lines to install micro-ROS as a dependency for platformio:

lib_deps =
    https://github.com/micro-ROS/micro_ros_platformio

Writing firmware for ESP32
#

Copy following lines to src/main.cpp

#include <Arduino.h>
#include <micro_ros_platformio.h>

#include <rcl/rcl.h>
#include <rclc/rclc.h>
#include <rclc/executor.h>

#include <std_msgs/msg/int32.h>

#if !defined(MICRO_ROS_TRANSPORT_ARDUINO_SERIAL)
#error This example is only avaliable for Arduino framework with serial transport.
#endif

rcl_publisher_t publisher;
std_msgs__msg__Int32 msg;

rclc_executor_t executor;
rclc_support_t support;
rcl_allocator_t allocator;
rcl_node_t node;
rcl_timer_t timer;

#define RCCHECK(fn) { rcl_ret_t temp_rc = fn; if((temp_rc != RCL_RET_OK)){error_loop();}}
#define RCSOFTCHECK(fn) { rcl_ret_t temp_rc = fn; if((temp_rc != RCL_RET_OK)){}}

// Error handle loop
void error_loop() {
  while(1) {
    delay(100);
  }
}

void timer_callback(rcl_timer_t * timer, int64_t last_call_time) {
  RCLC_UNUSED(last_call_time);
  if (timer != NULL) {
    RCSOFTCHECK(rcl_publish(&publisher, &msg, NULL));
    msg.data++;
  }
}

void setup() {
  // Configure serial transport
  Serial.begin(115200);
  set_microros_serial_transports(Serial);
  delay(2000);

  allocator = rcl_get_default_allocator();

  //create init_options
  RCCHECK(rclc_support_init(&support, 0, NULL, &allocator));

  // create node
  RCCHECK(rclc_node_init_default(&node, "micro_ros_platformio_node", "", &support));

  // create publisher
  RCCHECK(rclc_publisher_init_default(
    &publisher,
    &node,
    ROSIDL_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Int32),
    "micro_ros_platformio_node_publisher"));

  // create timer,
  const unsigned int timer_timeout = 1000;
  RCCHECK(rclc_timer_init_default(
    &timer,
    &support,
    RCL_MS_TO_NS(timer_timeout),
    timer_callback));

  // create executor
  RCCHECK(rclc_executor_init(&executor, &support.context, 1, &allocator));
  RCCHECK(rclc_executor_add_timer(&executor, &timer));

  msg.data = 0;
}

void loop() {
  delay(100);
  RCSOFTCHECK(rclc_executor_spin_some(&executor, RCL_MS_TO_NS(100)));
}

(gracefully taken from micro_ros_platformio project)

Flashing firmware
#

Thankfully it is simple to flash firmware with platformio. Run

pio run -t upload

If you cannot connect to device it might be related to permissions of the serial port. Give yourself permissions for the serial port. If you can not find the serial, try

pio device list

Testing your configuration
#

Run following to check if our microros setup is running correctly:

docker run -it --rm -v /dev:/dev -v /dev/shm:/dev/shm --privileged --net=host microros/micro-ros-agent:$ROS_DISTRO serial --dev /dev/ttyUSB0 -v6

If everything has been setup up correctly you should be able to see your node sending messages. You can check if your node is connected by

ros2 node list

If you see an entry /micro_ros_platformio_node then everything is working.