Hello everyone, thanks for the attention! I am using Ros Kinetic on Ubuntu Mate as OS, running on a Raspbery Pi 3 I am trying to use an Arduino Mega 2560 to do a few things in my robot. Control my Stepper Motors, publish raw IMU data and publish encoder readings.

The codes can be located here: https://github.com/renanmb/Ros_arduino

The Problem is:

When I use Arduino with only one type of message it works. However, when it runs different callbacks and publishers of different types, for example: Boolean, Int32 and Float 32. It does not work.

I receive the following message on my Terminal:

[ERROR] [ 1433855869.447165] Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino

In my Github Repository called Ros_arduino:

The codes that do not work

ros_surp.ino (lowercase, the upper case one is missing stuff)

ROS_PWM.ino

The codes that do work

IMUROStest2.ino

chapter7_book.ino

chapter7bookblink_and ......

I thought it was the following erros:

• Buffer. Then I modified the buffer size and it keep giving me the same error. I used the following tutorial to change the buffer:
• Baud rate. then I changed the baud rate using rosrun rosserialpython serialnode.py _port:=/dev/ttyACM0 _baud:=????? and I added Serial.begin() with the desired baud rate in the arduino. It did not work, I kept receiving the same error message.
• Bad cable

So what should I do to fix it?

I want to know if there is a way to use my Arduino to control multiple actuators and publish IMU and encoder data. If not I want to know if there is any board that I could use for that. I am considering as a last case scenario to use multiple arduinos, because it is an Ugly solution and takes a lot of space.

I am using the Arduino because of the AVR micro controller that is easier and generates a much better PWM signal than ARM based micro controller.

My code: ros_surp.ino

gives me

[ERROR] [ 1433855869.447165] Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino

#include <Wire.h>
#include <ros.h>

#include <Adafruit_Sensor.h>
#include <Adafruit_LSM303.h>
#include <Adafruit_LSM303_U.h>

#include <std_msgs/Float32.h>
#include <std_msgs/Int32.h>
#include <std_msgs/Bool.h>

#include <Encoder.h> //encoder library - http://www.pjrc.com/teensy/td_libs_Encoder.html

#include <PWM.h> //PWM library for controlling the steppers

/* Assign a unique ID to the sensors */
Adafruit_LSM303_Accel_Unified accel = Adafruit_LSM303_Accel_Unified(30301);
//******** add later gyroscope and magnet sensor for more complex positioning


//  Both pins must have interrupt capability
Encoder myEnc(2,3);

//Motor pins
//use pin 11 on the Mega instead, otherwise there is a frequency cap at 31 Hz
const int step_pin1 = 11;     // the pin that define the steps
const int dir_pin1 = 22;      // the dir pin
const int step_pin2 = 12;     // the pin that define the steps
const int dir_pin2 = 24;
int32_t frequency1 = 0; //frequency (in Hz)
int32_t frequency2 = 0; //frequency (in Hz)

ros::NodeHandle nh;
std_msgs::Float32 velLinear_x;
std_msgs::Float32 velAngular_z;
std_msgs::Int32 encoder;
std_msgs::Bool motor1_dir;
std_msgs::Bool motor2_dir;
std_msgs::Float32 motor1_cmd;
std_msgs::Float32 motor2_cmd;

ros::Publisher velLinear_x_pub("velLinear_x" , &velLinear_x);
ros::Publisher velAngular_z_pub("velAngular_z" , &velAngular_z);
ros::Publisher encoder_pub("encoder" , &encoder);

void initSensors(){
   if(!accel.begin())
  {
    /* There was a problem detecting the LSM303 ... check your connections */
    Serial.println(F("Ooops, no LSM303 detected ... Check your wiring!"));
    while(1);
  }
}

void motor1_cmd_callback(const std_msgs::Float32& motor1_cmd){
  frequency1 = (int)motor1_cmd.data;  
}

void motor2_cmd_callback(const std_msgs::Float32& motor2_cmd){
  frequency2 = (int)motor2_cmd.data;
}

void motor1_dir_callback(const std_msgs::Bool& motor1_dir){
  if(motor1_dir.data == true){
    digitalWrite(dir_pin1, HIGH);
  }
  else{
    digitalWrite(dir_pin1, LOW);
  }
}

void motor2_dir_callback(const std_msgs::Bool& motor2_dir){
  if(motor2_dir.data == true){
    digitalWrite(dir_pin2, HIGH);
  }
  else{
    digitalWrite(dir_pin2, LOW);
  }
}

 ros::Subscriber<std_msgs::Float32> sub1("motor1_cmd", &motor1_cmd_callback );
 ros::Subscriber<std_msgs::Float32> sub2("motor2_cmd", &motor2_cmd_callback );
 ros::Subscriber<std_msgs::Bool> sub3("motor1_dir", &motor1_cmd_callback );
 ros::Subscriber<std_msgs::Bool> sub4("motor2_dir", &motor2_cmd_callback );

void setup(void){ /* this is the same as void setup() but for older C and C++ */
  //Serial.begin(1000000);
  //initialize all timers except for 0, to save time keeping functions
  InitTimersSafe(); 

  nh.initNode();
  nh.advertise(velLinear_x_pub);
  nh.advertise(velAngular_z_pub);
  nh.advertise(encoder_pub);
  nh.subscribe(sub1);
  nh.subscribe(sub2);
  nh.subscribe(sub3);
  nh.subscribe(sub4);

  // =======================================================================================
  /* ================ PWM Function  ======================================================= */

  //PWM to the motors
  pinMode(step_pin1, OUTPUT);
  pinMode(dir_pin1, OUTPUT);
  SetPinFrequency(step_pin1, frequency1); //change for the callback function of motor1_cmd
  pinMode(step_pin2, OUTPUT);
  pinMode(dir_pin2, OUTPUT);
  SetPinFrequency(step_pin2, frequency2); //change for the callback function of motor2_cmd

  while(true){
    //setting the duty to 50% with the highest possible resolution that 
    //can be applied to the timer (up to 16 bit). 1/2 of 65536 is 32768.
    pwmWriteHR(step_pin1, 32768);
    pwmWriteHR(step_pin2, 32768);
  }

   //initialize the sensor and its bandwidth here
   initSensors();

}

long oldPosition  = -999;

void loop(void){ /* this is the same as void loop() but for older C and C++ */

  /*create here the variables to store de data received from the sensor.*/
  /* Objects */
  sensors_event_t accel_event;

  /* Read the accelerometer */
  accel.getEvent(&accel_event);

  /* How do I insert in the right units ? */
  velLinear_x.data = accel_event.acceleration.x ;
  velAngular_z.data = accel_event.acceleration.y ;

  /* Encoder reading - long in arduino is the same as int32
     This code gives a int32 number that can be copared to get speed
     myEnc.*/
  long newPosition = myEnc.read();
  if (newPosition != oldPosition) {
    oldPosition = newPosition;
    encoder.data = newPosition;
  }

  velLinear_x_pub.publish(&velLinear_x);
  velAngular_z_pub.publish(&velAngular_z);
  encoder_pub.publish(&encoder);

  nh.spinOnce();
  delay(10);
}

Same error message for this code:

ROS_PWM.ino

#include <Wire.h>
#include <ros.h>

#include <std_msgs/Float32.h>
#include <std_msgs/Int32.h>
#include <std_msgs/Bool.h>

#include <PWM.h> //PWM library for controlling the steppers

//Motor pins
//use pin 11 on the Mega instead, otherwise there is a frequency cap at 31 Hz
const int step_pin1 = 11;     // the pin that define the steps
const int dir_pin1 = 22;      // the dir pin
const int step_pin2 = 12;     // the pin that define the steps
const int dir_pin2 = 24;
int32_t frequency1 = 0; //frequency (in Hz)
int32_t frequency2 = 0; //frequency (in Hz)

ros::NodeHandle nh;
std_msgs::Bool motor1_dir;
std_msgs::Bool motor2_dir;
std_msgs::Float32 motor1_cmd;
std_msgs::Float32 motor2_cmd;

//Motor_cmd Subscriber
void motor1_cmd_callback(const std_msgs::Float32& motor1_cmd){
  frequency1 = (int)motor1_cmd.data;  
}

void motor2_cmd_callback(const std_msgs::Float32& motor2_cmd){
  frequency2 = (int)motor2_cmd.data;
}

//Motor_dir Subscriber
void motor1_dir_callback(const std_msgs::Bool& motor1_dir){
  if(motor1_dir.data == true){
    digitalWrite(dir_pin1, HIGH);
  }
  else{
    digitalWrite(dir_pin1, LOW);
  }
}

void motor2_dir_callback(const std_msgs::Bool& motor2_dir){
  if(motor2_dir.data == true){
    digitalWrite(dir_pin2, HIGH);
  }
  else{
    digitalWrite(dir_pin2, LOW);
  }
}

 ros::Subscriber<std_msgs::Float32> sub1("motor1_cmd", &motor1_cmd_callback );
 ros::Subscriber<std_msgs::Float32> sub2("motor2_cmd", &motor2_cmd_callback );
 ros::Subscriber<std_msgs::Bool> sub3("motor1_dir", &motor1_cmd_callback );
 ros::Subscriber<std_msgs::Bool> sub4("motor2_dir", &motor2_cmd_callback );

void setup(void){ /* this is the same as void setup() but for older C and C++ */
  //initialize all timers except for 0, to save time keeping functions
  InitTimersSafe(); 

 nh.initNode();
 nh.subscribe(sub1);
 nh.subscribe(sub2);
 nh.subscribe(sub3);
 nh.subscribe(sub4);

  // =======================================================================================
  /* ================ PWM Function  ======================================================= */

  //PWM to the motors
  pinMode(step_pin1, OUTPUT);
  pinMode(dir_pin1, OUTPUT);
  SetPinFrequency(step_pin1, frequency1); //change for the callback function of motor1_cmd
  pinMode(step_pin2, OUTPUT);
  pinMode(dir_pin2, OUTPUT);
  SetPinFrequency(step_pin2, frequency2); //change for the callback function of motor2_cmd

  while(true){
    //setting the duty to 50% with the highest possible resolution that 
    //can be applied to the timer (up to 16 bit). 1/2 of 65536 is 32768.
    pwmWriteHR(step_pin1, 32768);
    pwmWriteHR(step_pin2, 32768);
  }

}

void loop(void){ /* this is the same as void loop() but for older C and C++ */
  nh.spinOnce();
  delay(10);
}