I am looking for a simple timer sketch. It should turn-on a relay at 45, 60, or 90 minutes, etc., by changing a variable in the code.
I am guessing that this can be done with millis (but I don't know how to write the sketch myself). I hope to upload the sketch and run two wires to the relay. I'm confident a simple program like it must have been done before.
I have been trying without success to make a countdown timer sketch work which involves a LCD display. It is a nice project, but, for my purpose, the LCD display is unnecessary.
Anyway, I can't get it to work. The problem seems to be with the button circuitry. That's what gave me the idea to eliminate the buttons and LCD, and simply write a variable for the desired time in the code.
A link to the LCD project is copied below. The relay I want to control is shown in the second link. Briefly, it operates at 3-48VDC input, which is perfect for use with an Uno board.https://www.electronicshub.org/adjustable-timer/https://www.sparkfun.com/products/14236