void myISR( void );

 

void setup() {

  // put your setup code here, to run once:

  Serial.begin(115200);

  attachInterrupt(digitalPinToInterrupt(2), myISR, FALLING);

 

}

 

volatile uint8_t messageReady = 0;

volatile unsigned long elapsedTime;

volatile uint8_t message[4];

 

void loop() {

 

  // put your main code here, to run repeatedly:

  if ( messageReady == 1 ){

    messageReady = 0;

    for ( int i = 0; i < 4; i++){

      Serial.print(message[i], HEX);

      Serial.print(" ");

    }

    Serial.println(" ");

  }

 

}void myISR( void ){

  static unsigned long previousMicros = micros();

  static uint8_t byteIndex = 0;

  static uint8_t bitIndex = 0;

 

  elapsedTime = micros() - previousMicros;

  previousMicros = micros();

  if ( elapsedTime > 10000 && elapsedTime < 15000){

    // Start of message

    byteIndex = 0;

    bitIndex = 0;

  }

 

  if ( elapsedTime > 1000 && elapsedTime < 1500 ){

    // We have a zero

    bitWrite( message[byteIndex], bitIndex, 0);

    bitIndex++;

    if (bitIndex > 7){

      byteIndex++;

      bitIndex = 0;

    }

  }

 

  if ( elapsedTime > 2000 && elapsedTime < 2500 ){

    // We have a one

    bitWrite( message[byteIndex], bitIndex, 1);

    bitIndex++;

    if (bitIndex > 7){

      byteIndex++;

      bitIndex = 0;

    }

  }

 

  if ( byteIndex > 3 ){

    // We have the entire message

    messageReady = 1;

    byteIndex = 0;

  }

 

}