Simplest UNO Digital Clock Ever © GPL3+

I tried the clock from here:

https://www.hackster.io/Annlee_Fores/simple-arduino-digital-clock-without-rtc-7d4303

and found lots of problems in it, so decided to improve it.

Now the incrementation of s will be every 1 second and no more depending from the loop{} execution time.

RESISTORS AND POTENTIOMETER SUCKS, I removed them completely.

For the Pullup of the time setting buttons, you can use the one integrated in the ATmega328P chip...

pinMode(hs, INPUT_PULLUP) avoids to use a external pullup.

Avoid the LCD Contrast Potentiometer !

The contrast of the LCD can be set with a Arduino PWM signal.

Same for the Backlight, powered with the Arduino PWM signal, so it can be set on / off and intensity by the Arduino.

Here is a short video about this precision clock!