Problem with DC motor software, newby

Other Hardware 3rd Party Boards
1

Hello, i am having troubles with my DC motor. I was trying to make it so it can vary speed, the arduino starter book suggested me to try and do so. Here is my problem : No matter what, my arduino keeps spinning the same MAX speed.

const int switchPin = 2;
const int motorPin = 9;
const int potPin = A0;
int switchState = 0;
int potVal = 0; //Potentiometer value
int motorOut = 0; //The to be speed mapped from 0-1023 to 0-255

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(switchPin, INPUT);
  pinMode(motorPin, OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  switchState = digitalRead(switchPin);
  int potVal = analogRead(potPin);
  Serial.print("Etat du switch = ");
  Serial.println(switchState);
  Serial.print("potVal = ");
  Serial.println(potVal); 
  motorOut = map(potVal, 0, 1023, 0, 255);
  Serial.print("Valeur de MotorOut = "); 
  Serial.println(motorOut); //it actually works : printing value from 0-255
  float motorOut2 = motorOut/255*5; // Unused troubleshoot tries (overall useless)



  if (switchState == 1) { 
    
    digitalWrite(motorPin, motorOut); //Same motor speed no matter WHAT !
    delay(50);
  }

  else {
    digitalWrite(motorPin, LOW); //thankfully, it stops
    delay(50);
  }
  delay(5);
}
2

digitalWrite(motorPin, motorOut); //Same motor speed no matter WHAT !

You need to use an analog PWM pin, and analogWrite().

Please post a wiring diagram, and a link to the motor driver. Don't try to connect a motor directly to a digital pin, or power it from the Arduino 5V (even if the "starter book" tells you to do so).

Tutorial

What is printed out for "potVal"?

3

Thanks your for your fast answer :slight_smile:

I am litteraly using project 09 of the starter kit :

Project-09-Motorized-Pinwheel_bb-3355702147
Project-09-Motorized-Pinwheel_bb-33557021471863×1581 274 KB

potVal prints value map from 0-1023 (pot) to 0-255. It works and shows as i move it.

I don't know what the motor driver is but on it is written as follow :

TT MOTOR
20210703

4

The motor driver is the black object with 3 pins on the breadboard, which should be a MOSFET transistor.

What are the markings on it? Post a close up, focused picture of your setup, clearly showing all the wiring.

5

IMG_20230601_165544
IMG_20230601_1655441680×3648 245 KB

IMG_20230601_165705
IMG_20230601_1657051920×888 128 KB

the dual potentiometer doesnt really change much, it's only connected to the left one, that has white turning green wire connected to A0.

6

I MADE IT ! but i can't understand how it works :slightly_frowning_face: :

I just changed my
digitalWrite(motorPin, motorOut);

to

analogWrite(motorPin, motorOut);

Why does it work if my motorPin is acutally not on any analog, why is it analog write, and why does it works that way ?

7

The tutorial linked above explains that, or tries to. Read it, disregarding the difference in the driver used.