// The program allows you to set // the pulse duration and the pulse delay in ms // (meander, 20 Hz, 50/50 ms) int led = 13; // OUTPUT int dur = 50; // pulse duration (ms) int del = 50; // pulse delay (ms) void setup() { pinMode(led, OUTPUT); } void loop() { digitalWrite(led, HIGH); delay(dur); digitalWrite(led, LOW); delay(del); }