SparkFun Forums

[rhysonce]

When designing a basic program to test an H bridge I built, however, when using analogWrite to control the speed of my motor, the code locks and the outputs won't turn off. From doing some research this appears to have been a problem with the Leonardo as well. Something about the basic Arduino code not cancelling the PWM when digitalWrite is called.

~working code~

Code: Select all

int gogo;


void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
  
pinMode(A0, OUTPUT);
pinMode(A1, OUTPUT);
pinMode(A2, OUTPUT);
pinMode(A3, OUTPUT);

pinMode(A16, INPUT_PULLUP);
pinMode(A15, INPUT_PULLUP);
pinMode(A14, INPUT_PULLUP);
}





void loop() {
  

//free spinning, all MOSFET off. Clear any stray code since I don't know what I'm doing. 
digitalWrite(A3, LOW);
digitalWrite(A2, LOW);
digitalWrite(A1, LOW);
digitalWrite(A0, LOW);

gogo = analogRead(A5)/4;

Serial.print("Throttle is set to ");
Serial.print(gogo);
Serial.println(" of 255.");


  //brake
if (!digitalRead(16)){


  digitalWrite(A3, LOW);
  digitalWrite(A1, LOW);
  digitalWrite(A2, HIGH);
  digitalWrite(A0, HIGH);

}

//clockwise rotation
if (!digitalRead(14)){


  digitalWrite(A2, LOW);
  digitalWrite(A1, LOW);
  digitalWrite(A3, HIGH);
    digitalWrite(A0, HIGH);
}

//counter clockwise rotation
if (!digitalRead(15)){


  digitalWrite(A3, LOW);
  digitalWrite(A0, LOW);
  digitalWrite(A2, HIGH);
  digitalWrite(A1, HIGH);

}

  

delay(5);
}

~end working code~

~code that should work but doesn't?~

int gogo;


void setup() {
 
Serial.begin(9600);
  
pinMode(A0, OUTPUT);
pinMode(A1, OUTPUT);
pinMode(A2, OUTPUT);
pinMode(A3, OUTPUT);

pinMode(A16, INPUT_PULLUP);
pinMode(A15, INPUT_PULLUP);
pinMode(A14, INPUT_PULLUP);
}





void loop() {

digitalWrite(A3, LOW);
digitalWrite(A2, LOW);
digitalWrite(A1, LOW);
digitalWrite(A0, LOW);

gogo = analogRead(A5)/4;

Serial.print("Throttle is set to ");
Serial.print(gogo);
Serial.println(" of 255.");


  
if (!digitalRead(16)){


  digitalWrite(A3, LOW);
  digitalWrite(A1, LOW);
  digitalWrite(A2, HIGH);
  digitalWrite(A0, HIGH);

}

if (!digitalRead(14)){


  digitalWrite(A2, LOW);
  digitalWrite(A1, LOW);
  analogWrite(A3, gogo);
    analogWrite(A0, gogo);
}

if (!digitalRead(15)){


  digitalWrite(A3, LOW);
  digitalWrite(A0, LOW);
  analogWrite(A2, gogo);
  analogWrite(A1, gogo);

}

  

delay(5);
}

~end sad code~



If it is indeed my code that is just wrong, my apologies. But I do believe this has to do with the way the Artemis handles analogWrite.

[liquid.soulder]

Hmmm - digitalWrite does indeed not disable pwm output. This is because PWM output comes from a different peripheral. I think you need to reconfigure the pin to a normal digital output with pinMode(pin, OUTPUT); when you want it to stop being PWM

[rhysonce]

Is that something unique to the Artemis Arduino core? On my teensy as well as on other Arduinos digitalWrite will stop PWM output.

[liquid.soulder]

I knew this issue seemed familiar. We have considered it and decided that the best solution is to call pinMode to change back to a digital mode.
https://github.com/sparkfun/Arduino_Apollo3/issues/92

[rhysonce]

Thanks so much for the link! I agree with what was discussed there. I guess ill just have to add another line to my code