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Physical Computing

Motor Driver Experimentation

Today I experimented with connecting a motor driver to the Arduino. Here’s the circuit I used:

Circuit

While initially I had the motor turn on only when the button is depressed, I switched it to be on all the time, changing directions & speed using PWM when the button is pressed.

Code for this demo:
const int switchPin = 2;    // switch input
const int motor1Pin = 3;    // Motor driver leg 1 (pin 3, AIN1)
const int motor2Pin = 4;    // Motor driver leg 2 (pin 4, AIN2)
const int pwmPin = 5;       // Motor driver PWM pin


void setup() {
  // set the switch as an input:
  pinMode(switchPin, INPUT); 


  // set all the other pins you're using as outputs:
  pinMode(motor1Pin, OUTPUT);
  pinMode(motor2Pin, OUTPUT);
  pinMode(pwmPin, OUTPUT);


  // set PWM enable pin high so that motor can turn on:
  digitalWrite(pwmPin, HIGH);
}


void loop() {
  // if the switch is depressed, motor will turn on one direction slowly:
  if (digitalRead(switchPin) == LOW) {
    analogWrite(pwmPin, 72);
    digitalWrite(motor1Pin, LOW);   // set leg 1 of the motor driver low
    digitalWrite(motor2Pin, HIGH);  // set leg 2 of the motor driver high
  }
  // if the switch is low, motor will turn in the other direction quickly:
  else {
    analogWrite(pwmPin, 255);
    digitalWrite(motor1Pin, HIGH);  // set leg 1 of the motor driver high
    digitalWrite(motor2Pin, LOW);   // set leg 2 of the motor driver low
  }
}

For an extra challenge, I wanted to add a potentiometer to control the speed, leaving the button to control direction. Reviewing how I wired/coded a potentiometer week 2, Sophie-Ana and I configured that:

Code for this demo:
const int switchPin = 2;    // switch input
const int motor1Pin = 3;    // Motor driver leg 1 (pin 3, AIN1)
const int motor2Pin = 4;    // Motor driver leg 2 (pin 4, AIN2)
const int pwmPin = 5;       // Motor driver PWM pin
int dialValue = 0;          // Current value from pot


void setup() {
  // set the switch as an input:
  pinMode(switchPin, INPUT); 


  // set all the other pins you're using as outputs:
  pinMode(motor1Pin, OUTPUT);
  pinMode(motor2Pin, OUTPUT);
  pinMode(pwmPin, OUTPUT);


  // set PWM enable pin high so that motor can turn on:
  digitalWrite(pwmPin, HIGH);
}


void loop() {
  dialValue = analogRead(A0);
  analogWrite(pwmPin, 255 - (dialValue / 4));
  // if the switch is depressed, motor will turn in one direction:
  if (digitalRead(switchPin) == LOW) {
    analogWrite(pwmPin, 72);
    digitalWrite(motor1Pin, LOW);   // set leg 1 of the motor driver low
    digitalWrite(motor2Pin, HIGH);  // set leg 2 of the motor driver high
  }
  // if the switch is low, motor will turn in the other direction:
  else {
    digitalWrite(motor1Pin, HIGH);  // set leg 1 of the motor driver high
    digitalWrite(motor2Pin, LOW);   // set leg 2 of the motor driver low
  }
}