Help with interrupt problem

Hi,

What behavior are you seeing with this code?  From looking at it, it looks like you turn the light on when pin 18 is low but never turn it off again.  Also, how have you got the switch wired to pin 18?

Jeff.

You'll need to adjust your light() method to handle both turning on and off, for example, you can read the current state of the pin (or make a variable to toggle the state)

void light() {

     // Check if pin is high

     if(digitalRead(LED_PIN))

     {

          digitalWrite(LED_PIN, LOW);

     }

     // Pin is low, so turn high

     else

     {

          digitalWrite(LED_PIN, HIGH);

     }

}

Thanks for your help. Yes, you are right, the light turns on when I turn on the switch 18 and never goes out when I release it. Also the motor only runs when the switch 18 is on and turns continuously very slowly when switch 18 is off.

This is not the result I wanted. I needed the light to turn on and the motor to come to a complete stop when switch 18 is turned on, and the light to go off and the motor to turn when I release the switch.

The switch is wired with one terminal connected to pin 18 and ground with a resistor. The other terminal is connected to the positive power supply.

NB. Switch 18 is the one I'm using to turn on the interrupt for pin 18.

Just to draw a better picture.  Can you verify the description of your circuit here.

You have VCC going to terminal 1 of a switch.  Terminal 2 of the switch is connected directly to pin 18.  Also connected to pin 18 is resister lead 1.  Resistor lead 2 is connected to ground.

If this is the case i would re-visit the mode setting on your interrupt attachment.  When set to HIGH the interrupt will fire whenever the pin is high.  Meaning a long press could result in multiple firings.  I would suggest switching to either CHANGE/RISING/FALLING depending on how much more you want to add to the interrupt handler.  To stop the motor you will need to flag the main loop somehow.  I would recommend adding a boolean that you can set or clear in the interrupt.  Then you can check this boolean in the main loop. 

I don't have the means to build and test this but it should function.  Another option is to setup more of an interrupt based loop so that you have more of an instantaneous start/stop.  The following example would require that you get to the end of the loop (which current looks like 4 seconds) to actually stop.

Example:

boolean runMotor = false;

void setup() {

  pinMode(DIR_PIN, OUTPUT);

  pinMode(STEP_PIN, OUTPUT);

  pinMode(LED_PIN, OUTPUT);

  // switch input

  pinMode(18, INPUT);

  // attach the interrupt on pin 18

  attachInterrupt(SWITCH_PIN, light, CHANGE);

}

void light() {

  // Check if motor is running

  if(runMotor)

  {

  digitalWrite(LED_PIN, HIGH);

  runMotor = false

  }

  // Motor is not running, start it again

  else

  {

  digitalWrite(LED_PIN, LOW);

  runMotor = true;

  }

}

void loop(){

  if(runMotor)

  {

  //rotate a specific number of degrees

  rotateDeg(360, 1);

  delay(1000);

  rotateDeg(-360, .1);  //reverse

  delay(1000);

  //rotate a specific number of microsteps (8 microsteps per step)

  //a 200 step stepper would take 1600 micro steps for one full revolution

  rotate(1600, .5);

  delay(1000);

  rotate(-1600, .25); //reverse

  delay(1000);

  }

  else

  {

  delay(100);

  }

}

void rotate(int steps, float speed){

  //rotate a specific number of microsteps (8 microsteps per step) - (negitive for reverse movement)

  //speed is any number from .01 -> 1 with 1 being fastest - Slower is stronger

  int dir = (steps > 0)? HIGH:LOW;

  steps = abs(steps);

  digitalWrite(DIR_PIN,dir);

  float usDelay = (1/speed) * 70;

  for(int i=0; i < steps; i++){

  digitalWrite(STEP_PIN, HIGH);

  delayMicroseconds(usDelay);

  digitalWrite(STEP_PIN, LOW);

  delayMicroseconds(usDelay);

  }

}

void rotateDeg(float deg, float speed){

  //rotate a specific number of degrees (negitive for reverse movement)

  //speed is any number from .01 -> 1 with 1 being fastest - Slower is stronger

  int dir = (deg > 0)? HIGH:LOW;

  digitalWrite(DIR_PIN,dir);

  int steps = abs(deg)*(1/0.225);

  float usDelay = (1/speed) * 70;

  for(int i=0; i < steps; i++){

  digitalWrite(STEP_PIN, HIGH);

  delayMicroseconds(usDelay);

  digitalWrite(STEP_PIN, LOW);

  delayMicroseconds(usDelay);

  }

}

Thanks. I will test it and let you know how it goes.

Some other recommendations i can make (maybe once you get this part working) are

1. Separate each of the rotate() methods and put an if( runMotor ) around each.  This would give you an easy way to lower the time between a button press and stopping the motors (to more like 1 second)

2.  Look into timer interrupts.  You could set up a timer with an interrupt to fire and have that handle rotating the motor.  I would set it up with one rotate() method and just switch through the degrees and speeds you use.  Then you can control whether the timer is running or not when the button is pressed.

3. Incorporate the runMotor variable into the rotate() method itself.  This could provide instantaneous response from a button press, but would require the runMotor variable to be somewhat global...