A4988 driver for stepper motor

Good day! I am using an A4988 driver module to drive my nema 17 stepper motor

I tried to translate the arduino code below into a matlab code, but it doesnt work the same way as it does when i use the arduino IDE. What happens instead is that the motor seems to find it hard to make steps

this is the matlab code that i wrote based on the arduino code by Dejan Nedelkovski

clc;
clear;
a = arduino('com5', 'mega2560');

writeDigitalPin(a, 'D4', 1);
for ctr = 1:200
    writeDigitalPin(a, 'D3', 1);
    pause(0.0005);
    writeDigitalPin(a, 'D3', 0);
    pause(0.0005);
end
pause(1);

writeDigitalPin(a, 'D4', 0);
for ctr = 1:200
    writeDigitalPin(a, 'D3', 1);
    pause(0.0005);
    writeDigitalPin(a, 'D3', 0);
    pause(0.0005);
end
pause(1);

this is the arduino code

/*     Simple Stepper Motor Control Exaple Code
 *      
 *  by Dejan Nedelkovski, www.HowToMechatronics.com
 *  
 */
// defines pins numbers
const int stepPin = 3; 
const int dirPin = 4; 
 
void setup() {
  // Sets the two pins as Outputs
  pinMode(stepPin,OUTPUT); 
  pinMode(dirPin,OUTPUT);
}
void loop() {
  digitalWrite(dirPin,HIGH); // Enables the motor to move in a particular direction
  // Makes 200 pulses for making one full cycle rotation
  for(int x = 0; x < 200; x++) {
    digitalWrite(stepPin,HIGH); 
    delayMicroseconds(500); 
    digitalWrite(stepPin,LOW); 
    delayMicroseconds(500); 
  }
  delay(1000); // One second delay
  
  digitalWrite(dirPin,LOW); //Changes the rotations direction
  // Makes 400 pulses for making two full cycle rotation
  for(int x = 0; x < 200; x++) {
    digitalWrite(stepPin,HIGH);
    delayMicroseconds(500);
    digitalWrite(stepPin,LOW);
    delayMicroseconds(500);
  }
  delay(1000);
}

[Walter Roberson]

What is the reason for rewriting it as MATLAB code?

Each time that you invoke writeDigitalPin, MATLAB has to talk to a command interpreter on the arduino, sending it a command and appropriate data, and the command interpreter has to parse and validate the parameters and then execute the appropriate functionality. That will always be slower than dedicated code on the Arduino like you already have.

[Adrian Dwight]

i am rewriting the code in matlab since i am using the stepper motor in conjunction with the matlab image processing features.

thanks you sir. so its the time it takes to communicate between matlab and arduino that's causing the motor to run differently? is there any way to go around this problem? thanks again

[Adrian Dwight]

i tried the writePWMDutyCycle command, the stepper motor runs smoothly for some time depending on the pause value, but by doing so i am unable to control the number of steps. I need to control the number of steps though

[Walter Roberson]

Using writeDigitalPin is relatively slow. It is more efficient to have a dedicated program on the arduino that listens for inputs (especially binary instead of text) from the MATLAB side and sends results to the MATLAB side, and takes care of the pin manipulation on the arduino side. You could send pulse duty cycle and duration information. Or, especially with quadrature motors, you could send target positions and let the Arduino take care of the pulses to get there.

Note: if you are using a USB to serial connection to talk between the Arduino and MATLAB, then you are limited to at most 1000 transactions per second because of the way that USB serial is scheduled on the Arduino. There is an alternate device available that is Arduino-like that schedules immediately and so can send more than 1000 times per second... but you could still have some difficulty sending to it from the MATLAB side.

[Adrian Dwight]

i tried the code below, but the stepper motor doesn't seem to respond. Im guessing this is because the serial data is gone after a few moments?:

MATLAB:

clc;
clear;
serialNano = serial('COM7', 'BaudRate', 9600);
while 1
sendData = input('Enter data: ');
fopen(serialNano);
    switch sendData
        case 1
            fprintf(serialNano, '%s', char(1));
            pause(1);
        case 2
            fprintf(serialNano, '%s', char(2));
            pause(1);
    end
fclose(serialNano);
end

ARDUINO

int receivedData;


void setup() 
{
  pinMode(6,OUTPUT); //Step1
  pinMode(7,OUTPUT); //Direction1
  pinMode(9,OUTPUT); //Step2
  pinMode(10,OUTPUT);//Direction2
  Serial.begin(9600);
}

void loop() 
{
if(Serial.available() > 0)
{
  receivedData = Serial.read();
  if (receivedData == 1)
  {
      digitalWrite(7,LOW); 
      for(int x = 0; x < 349; x++) 
      {
        digitalWrite(6,HIGH); 
        delayMicroseconds(500); 
        digitalWrite(6,LOW); 
        delayMicroseconds(500); 
      }
      delay(1000); 

      digitalWrite(10,HIGH); 
      for(int x = 0; x < 25; x++) 
      {
        digitalWrite(9,HIGH); 
        delay(5); 
        digitalWrite(9,LOW); 
        delay(5); 
      }
      delay(1000);
      digitalWrite(10,LOW); 
      for(int x = 0; x < 25; x++) 
      {
        digitalWrite(9,HIGH);
        delay(5); 
        digitalWrite(9,LOW); 
        delay(5); 
      }
      delay(1000);
      digitalWrite(7, HIGH); 
      for(int x = 0; x < 349; x++) 
      {
        digitalWrite(6,HIGH);
        delayMicroseconds(500);
        digitalWrite(6,LOW);
        delayMicroseconds(500);
      }
      digitalWrite(11, HIGH);
      delay(1000);
  }
  else if (receivedData == 2)
  {
      digitalWrite(7,LOW);
      for(int x = 0; x < 1297; x++) 
      {
        digitalWrite(6,HIGH); 
        delayMicroseconds(500); 
        digitalWrite(6,LOW); 
        delayMicroseconds(500); 
      }
      delay(1000); 
      digitalWrite(10,HIGH); 
      for(int x = 0; x < 25; x++) 
      {
        digitalWrite(9,HIGH); 
        delay(5); 
        digitalWrite(9,LOW); 
        delay(5); 
      }
      delay(1000);
      digitalWrite(10,LOW);
      for(int x = 0; x < 25; x++) 
      {
        digitalWrite(9,HIGH);
        delay(5); 
        digitalWrite(9,LOW); 
        delay(5); 
      }
      delay(1000);
      digitalWrite(7, HIGH); 
      for(int x = 0; x < 1297; x++) 
      {
        digitalWrite(6,HIGH);
        delayMicroseconds(500);
        digitalWrite(6,LOW);
        delayMicroseconds(500);
      }
      digitalWrite(11, HIGH);
      delay(1000);
  }
}
}

[Paul Bayron]

Hi, everyone any update on this thread? I'm also trying to do the same thing but I can't get Matlab and Arduini IDE code to "talk" to each other.

[Rajbir Singh]

I am facing this same problem

[Yasya Khalif]

hi, have you found the solution? i need to interface matlab to arduino, and control the motor using driver motor drv8825

[明炀 范]

I am also concerning this question