Reading a variable set in an ISR, or using millis() for time within while loop?

Projects Programming
8

So you want something like this?

const byte LedPin = 8;
const byte SwinPin = 3;
volatile boolean StartSignal = false;
unsigned long MaxStartTime = 5000;  // StartSignal must be set within 5 seconds
unsigned long StartTime;
void setup() {
  pinMode(LedPin, OUTPUT);
  pinMode(SwinPin, OUTPUT);
  // initialize timer1
  cli();           // disable all interrupts
  TCCR3A = 0;      // Clean the registers
  TCCR3B = (1 << CS12) ;   // Prescaler 1024
  TIMSK3 |= (1 << TOIE3);   // enable timer overflow interrupt
  sei();             // enable all interrupts
  StartTime = millis();
}
ISR(TIMER3_OVF_vect) {        // interrupt service routine
  digitalWrite(LedPin, !digitalRead(LedPin));
  StartSignal = true;
}
void loop() {
  static boolean running = false;
  // Wait for start signal from ISR
  if (!running) {
    if (StartSignal) {
      running = true;
    } else {
      if (millis() - StartTime >= MaxStartTime) {
        // ERROR: StartSignal did not get set in time
      }
    }
    return;
  }  //end if (!runing)
  // RUNNING.  Do the stuff
}