Demo Video

[password: physcomp]

I made an instrument with a SPST switch and a Photoresistor. I had a hard time debugging during this time, and I finally realized that Serial printing was causing the time to not flow precisely.

The code was a simple modification of the Event Loop program, but I really dissected it and have grown to understand it.

const int outputPin1 = 4;

const int photoval = A0;
int val = 0; 

const int switchVal = 9;

/****************************************************************/
// This function is called once after reset to initialize the program.
void setup()
{
  Serial.begin(9600); // for debugging
  
  pinMode( outputPin1, OUTPUT );
  pinMode( photoval, INPUT);
}

long next_output_time_1 = 0;        // timestamp in microseconds for when next to update output 1

long output_interval_1 = 500;       // interval in microseconds between output 1 updates

int output_state_1 = LOW;           // current state of output 1

/****************************************************************/
// This function is called repeatedly as fast as possible from within the
// built-in library to poll program events.

void loop()
{
  
  val = analogRead(photoval);
  int newVal = map(val,300,800,1000,1500);

  bool hey = digitalRead(switchVal);
  // read the current time in microseconds

  long now = micros();

  // Polled task 1 for output 1.  Check if the next_output_time_1 timestamp has
  // been reached; if so then update the output 1 state.
  if (now > next_output_time_1) {

    // reset the timer for the next polling point
//    next_output_time_1 = now + output_interval_1;
    next_output_time_1 = now + newVal;

    // toggle the output_state_1 variable
    output_state_1 = !output_state_1;

    // update output pin 1 with the new value
    
    if (hey == HIGH) {
      digitalWrite( outputPin1, output_state_1 );
    }
  }
}
/****************************************************************/