arduinoTrinketCode.txt

volatile unsigned long lastRisingEdge = 0;
volatile unsigned long period = 0;

// Desired on and off times in milliseconds
unsigned long desiredOnTime = 10;
unsigned long desiredOffTime = 10;

// Pin assignments
const int inputPin = 2;  // Pin to read the incoming frequency
const int outputPin = 13; // Pin to output the on/off signal

void setup() {
  pinMode(inputPin, INPUT);
  pinMode(outputPin, OUTPUT);
  
  // Attach an interrupt to the input pin on the RISING edge
  attachInterrupt(digitalPinToInterrupt(inputPin), onRisingEdge, RISING);
}

void loop() {
  unsigned long currentPeriod;

  // Safely read the shared 'period' variable
  noInterrupts();
  currentPeriod = period;
  interrupts();

  // Check if a period has been measured
  if (currentPeriod > 0) {
    // Turn the output pin on
    digitalWrite(outputPin, HIGH);
    delay(140); // 140ms (needs to be >70)

    // Turn the output pin off
    digitalWrite(outputPin, LOW);
    delay(800); // 800ms (needs to be >400)
  }
}

void onRisingEdge() {
  unsigned long currentRisingEdge = micros();
  period = currentRisingEdge - lastRisingEdge;
  lastRisingEdge = currentRisingEdge;
}