Hi! “Arduino Timer with on/off setpoint” is my most viewed instructable by far, so i got a lot of questions in the comments, inbox and youtube, about how to add minutes,seconds, days and save settings on the eeprom…. so i decided to bring an old code, made with PIC, to arduino, easier to share and make.
I tried to make this project compact, easy to use and set up, with 3 buttons and a 16x2 lcd.The interface is based on my previous instructable “Turn single screen into multiple screens”. If you want to learn how this interface was made, please visit:
https://www.instructables.com/id/Arduino-LCD-16x2-Turn-Single-Screen-Into-Multiple-/
Here you have 6 codes to choose:
All timers are hours,minutes and seconds (on/off) programmables. Save data on the eeprom.
-1Timer for everyday,
-1Timer, selectable day
-4 Timers. 1 relay, for everyday
All timers has a “simple” version, that means, without lcd interface. Useful if you want to save money or don’t need to chage the settings periodically.
These timers can recover the data and work even in case of power failure. The code was made to activate the relay at any moment.
We’ll start from the basic timer to the more complete one.With this timer you can even turn on something for a second!
You will need:
-Arduino UNO
-LCD 16x2 (I2C)
-RTC 3231 module
-Push buttons x3
-10K resistors x3
-Relay module x1
-Breadboard,wires,etc”

Link