Converting serial signal (12V-5V) and reading it using Arduino - Electrical Engineering Stack Exchange

I'm trying to read some commands from a device that uses non-standard voltage levels for serial communication. It uses 0V for 0 and 12V for 1. For all I know, TTL levels are 0-5V, so if I want to

analogRead() erratic readings through op amp - General Electronics

12v signal to 5v with LM7805 - General Electronics - Arduino Forum

How does an Arduino actually read a high signal on a pin

12v Pulse signal to 5v pulse signal - Project Guidance - Arduino Forum

Can I covert a 3.3v/5v USB TTL Serial device to 1.8v using a

Recover Bricked ATtiny Using Arduino as high voltage programmer

How to make connections from digital energy meter to Arduino - Quora

microcontroller - How do I read the state of AC switch, through a

How to give 9v DC output when a 5v DC input is given through