How to use 4-20mA sensor with an Arduino Youtube link: https://youtu.be/yrHJ84ePtIw You probably came here because of the youtube video right? It's written in Arduino so ask your lawyer to read their official license. Most people read through it before using Arduino IDE right? you can do whatever you want with it as long as your lawyer says it's ok. You won't hear from me (or my imaginary lawyer), so long as you don't blame me for your code not working. The author doesn't provide any warranty / support, but feel free to drop me a comment on youtube if you have any questions. the LCD library is "hd44780" by Bill Perry, you can install it directly from Arduino IDE's library manager