GPIO (and therefor I2C) cannot be used at 5v. You will need to use a level shifter on the I2C lines if you want to run the board at 5v. Connections on Raspberry Pi Pico board, other boards may vary.

Seeed Studio product page: https://www.seeedstudio.com/Raspberry-Pi-RGB1602-LCD-Module.html Product pages links to this wiki: https://wiki.52pi.com/index.php/52Pi-BPi ...

Learn how to easily adjust the contrast of a 1602 LCD display using Arduino. In this quick tutorial, I’ll show you a simple trick to control the contrast electronically, without relying solely on the ...