// Loop Monitor – this checks that the loop() is executed at least once every 1mS // (c)2013 Forward Computing and Control Pty. Ltd. // www.forward.com.au // // This example code is in the public domain. // Pin 13 has an LED connected on most Arduino boards. // give it a name: int led = 13; // the setup routine runs once when you press reset: void setup() { // initialize the digital pin as an output. pinMode(led, OUTPUT); // add your other setup code here } // the loop routine runs over and over again forever: void loop() { // toggle the led output each loop The led frequency must measure >500Hz (i.e. <1mS off and <1mS on) if (digitalRead(led)) { digitalWrite(led, LOW); // turn the LED off by making the voltage LOW } else { digitalWrite(led, HIGH); // turn the LED on (HIGH is the voltage level) } // add the rest of your loop code here }