How to drive stepper motor using Arduino Accelstepper library with ros message?

Question

At the moment I am working on a code that should send a message to a arduino uno through rosserial to drive the stepper motor to move a speciafied number of steps. I was using a 28BYJ-48 with ULN2003 driver. Everything is hooked up correctly. My goal is to send a message using raspberry pi 2b to arduino uno through rosserial and that then the stepper moves to a certain position. However, I am not succeeding in this. I am using AccelStepper and at the moment I have the following code:

#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include <WProgram.h>
#endif
// Include the AccelStepper Library
#include <AccelStepper.h>
#include <ros.h>
#include <std_msgs/UInt16.h>
#include <std_msgs/Empty.h>

// Define step constant
#define HALFSTEP    8
// Creates an instance
// Pins entered in sequence IN1-IN3-IN2-IN4 for proper step sequence
AccelStepper stepper(HALFSTEP, 4, 6, 5, 7);

uint8_t run_flag = 0;

void startStepper(const std_msgs::Empty& start_msg) {
    run_flag = 1;
    digitalWrite(13, HIGH);
}

void runStepper(const std_msgs::UInt16& pos_msg) {
    run_flag = 2;
    stepper.moveTo(pos_msg.data);
}

ros::NodeHandle nh;
ros::Subscriber<std_msgs::Empty> stepperStart("stepper/start", &startStepper);
ros::Subscriber<std_msgs::UInt16> stepperRun("stepper/run", &runStepper);

void setup() {
    pinMode(13, OUTPUT);
    // set the maximum speed, acceleration factor,
    // initial speed and the target position
    stepper.setMaxSpeed(1000.0);
    stepper.setAcceleration(50.0);
    stepper.setSpeed(200);
    stepper.moveTo(2038);

    nh.initNode();
    nh.subscribe(motorStart);
    nh.subscribe(motorRun);
}

void loop() {   
    if (run_flag == 1) {
            stepper.run();
            if (stepper.distanceToGo() == 0) {
                    run_flag = 0;
                    digitalWrite(13, LOW);
                    stepper.setCurrentPosition(0);
            }
    }
    nh.spinOnce();
}

Run "roscore" in the terminal;
Open a new terminal and run the command "rosrun rosserial_python serial_node.py /dev/ttyACM0"
Open a new terminal and run the command "rostopic pub stepper/start std_msgs/Empty --once"

The code could run correctly for the first time after the arduino uno was power on. After that the arduino did not respond to the message from raspberry pi.

Any help you can offer me is appreciated! Thanks for your time.

How to drive stepper motor using Arduino Accelstepper library with ros message?

0 Answers0