#define ledbrd 13 #define rxpin 0 #define txpin 1 void setup() { pinMode(ledbrd, OUTPUT); // initialize digital pin 13 as an output. Serial.end(); // disable the serial port to start using the tx and rx and input port pinMode(rxpin, INPUT); //set the serial rx pin as general input pinMode(txpin,INPUT); // set the serial tx pin as general input } // Very low duty cycle blink to indicate idle mode of UNO board void loop() { digitalWrite(ledbrd, HIGH); // turn the LED on delay(1); // wait for a very short (minimum) time digitalWrite(ledbrd, LOW); // turn the LED off delay(4000); // wait for many seconds }