My Arduino (Uno) Christmas light Controller This program is used on an arduino uno with relays on pins 0-13 to control the 120V mains to turn lights on and off. The main part of this program is to use a random number generator to turn the lights on and off with no real order. There are some sections of the code where the lights will do a pre-programmed function, such as chace and blink after a set period of loops.