Micro-ROS agent not working for a serial communication between Arduino R4 Minima and Linux computer

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#1,502 opened on Aug 21, 2023 1 comment 1 reaction 0 assignees View on GitHub

Dominant language: C
Stars: 576
Forks: 146
PR merge metrics: No merged PRs in 30d

Description

Hello,

I am working on an Arduino R4 Minima with the goal to create a micro-ROS communication between this board and a Raspberry [3B+]. I am using ROS2 galactic, downloaded the micro-ROS application from source [here](https://micro.ros.org/docs/tutorials/core/first_application_linux/) and the micro-ROS Arduino package from [here](https://github.com/micro-ROS/micro_ros_arduino/tree/galactic).

The code uploaded on the Arduino was tested without micro-ROS via serial communication and works well, as I am able to insert a velocity value in the stepper motor to make it move and can get the left and right encoder tick values. Now, when I try to integrate it with micro-ROS functions and that I test it using a serial communication between my PC and the arduino, most of the time it doesn't work. Here is the Arduino code adapted for Micro-ROS, where a node with one subscriber (cmd_vel) and two pulbishers (left and right ticks):

```c
#include
#include
#include
#include
#include

#include
#include
#include
#include
#include

#include
#include
#include

MobileRobot robot;

float angularSpeed = Parameter::angularSpeed;
float linearSpeed = Parameter::linearSpeed;

rcl_node_t node;
rclc_support_t support;
rcl_allocator_t allocator;

// publishers
rcl_publisher_t pub_right_ticks;
std_msgs__msg__Int16 right_wheel_tick_count;

rcl_publisher_t pub_left_ticks;
std_msgs__msg__Int16 left_wheel_tick_count;

rclc_executor_t executor_pub;
rcl_timer_t timer;

// subscriber
rcl_subscription_t subscriber;
geometry_msgs__msg__Twist msg_twist;
rclc_executor_t executor_sub;

#define POWER_OPT A5
#define LED_PIN LED_BUILTIN

#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)) {} \
}

Timer timerTicks(Parameter::timerTicks);
Timer timerSpeedControl(Parameter::timerSpeed);
Timer timerPause(Parameter::timerPause);
bool speedPause = false;

//--------------------------- Interrupt Service Routines-------------------------------------

static void leftWheelInterruptA()
{
robot.leftWheelIncrementA();

}

static void rightWheelInterruptA()
{
robot.rightWheelIncrementA();
}

//--------------------------- Micro-ROS Functions-------------------------------------

// subscription callback
void twist2vel(const void *msgin) {
const geometry_msgs__msg__Twist *cmd_vel_msg = (const geometry_msgs__msg__Twist *)msgin;
// if velocity in x direction is 0 turn off LED, if 1 turn on LED
digitalWrite(LED_PIN, (cmd_vel_msg->linear.x == 0) ? LOW : HIGH);
linearSpeed = cmd_vel_msg->linear.x;
angularSpeed = cmd_vel_msg->angular.z*Parameter::rotationLength/(2*PI);
}

void error_loop() {
while (1) {
digitalWrite(LED_PIN, !digitalRead(LED_PIN));
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(&pub_right_ticks, &right_wheel_tick_count, NULL));
RCSOFTCHECK(rcl_publish(&pub_left_ticks, &left_wheel_tick_count, NULL));
}
}

//--------------------------- Setup -------------------------------------

void setup() {
//Serial.begin(9600);
set_microros_transports();

pinMode(POWER_OPT, OUTPUT);
digitalWrite(POWER_OPT, HIGH);

delay(1000);

timerTicks.init();
timerSpeedControl.init();
timerPause.init();

allocator = rcl_get_default_allocator();

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

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

// create subscriber
RCCHECK(rclc_subscription_init_default(
&subscriber,
&node,
ROSIDL_GET_MSG_TYPE_SUPPORT(geometry_msgs, msg, Twist),
"cmd_vel"));

// create publishers
RCCHECK(rclc_publisher_init_default(
&pub_right_ticks,
&node,
ROSIDL_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Int16),
"right_wheel_tick_count"));

RCCHECK(rclc_publisher_init_default(
&pub_left_ticks,
&node,
ROSIDL_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Int16),
"left_wheel_tick_count"));

// create timer, called every 1000 ms to publish
const unsigned int timer_timeout = 1000;
RCCHECK(rclc_timer_init_default(
&timer,
&support,
RCL_MS_TO_NS(timer_timeout),
timer_callback));

RCCHECK(rclc_executor_init(&executor_pub, &support.context, 2, &allocator));
RCCHECK(rclc_executor_add_timer(&executor_pub, &timer));

RCCHECK(rclc_executor_init(&executor_sub, &support.context, 1, &allocator));
RCCHECK(rclc_executor_add_subscription(&executor_sub, &subscriber, &msg_twist, &twist2vel, ON_NEW_DATA));

right_wheel_tick_count.data = 0;
left_wheel_tick_count.data = 0;
}

//--------------------------- Loop -------------------------------------

void loop() {
if (timerSpeedControl.isTime()){
robot.move(linearSpeed, angularSpeed / 9.39);
}

if (timerTicks.isTime()) {
left_wheel_tick_count.data = robot.getDataLeftWheel();
right_wheel_tick_count.data = robot.getDataRightWheel();
}

RCCHECK(rclc_executor_spin_some(&executor_pub, RCL_MS_TO_NS(100)));
RCCHECK(rclc_executor_spin_some(&executor_sub, RCL_MS_TO_NS(100)));
delay(50);
}
```

- Hardware: PC
- ROS version: Galactic
- RTOS: Ubuntu 20.04

- Steps to reproduce the issue:
``
`source install/setup.bash`
`ros2 run micro_ros_agent micro_ros_agent serial --dev /dev/ttyACM0 -b 921600`

The problems I encounter are the following:

1. When the USB-C cable is already plugged in, I get the following error:
![forum_error_terminal](https://github.com/micro-ROS/micro_ros_arduino/assets/102654647/168d3c33-5d51-4202-93fb-fd7aed0ee7df)
Although no other device is connected in this port and that I have the rights to read/write.

Once, after few resets, I was able to establish a correct communication and to move the robot using `ros2 run teleop_twist_keyboard teleop_twist_keyboard `, and I was getting correct subscriber values, even though there were some important delays.
This makes me think of the same problem than #241. I have not tried to modify the `client-host-colcon.meta` file located in `~/microros_ws/src/micro_ros_setup/config/host/generic` as I am not sure to what modify.

Would you have an idea as to how to solve this issue?

Thank you for your time.

- EDIT
When trying with the Arduino Zero, the program seems to work correctly, so this must be some sort of incompatibility between micro-ROS library and the Arduino R4 Minima.

Contributor guide

Open the contributing guide

Research direction

Start by reproducing the serial connection with the documented micro-ROS agent command, the Arduino R4 Minima sketch, and the logged client creation and deletion sequence. Compare this behavior with the referenced micro-ros_reconnection_example.ino and the working Arduino Zero setup; done means the R4 Minima establishes a stable session and creates the expected publishers and subscriber without repeated resets.

Written by the indexing model from the issue text.

Assessment

Tech stack: arduino, c, linux
Domain: embedded-iot, robotics
Issue type: Bug
Difficulty: 4/5
Estimated time: 3-5 days
Activity status: Stale
Clarity: Needs clarification
Newbie friendliness: 30/100

Micro-ROS agent not working for a serial communication between Arduino R4 Minima and Linux computer

Description

Contributor guide

Research direction

Assessment

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