LCD16x2 compatibility Uno R4

[eaglebauer]

Hi everyone,

I try to use a Shield LCD16x2 for a project on Arduino Uno R4, but only recently became aware of the different microcontroller types between prior hardware Revisions and R4.

Is the highly useful 16x2 shield compatible with the R4? What would I need to do in order to make it work? I need buttons and LCD functionality.

Best regards
eaglebauer

[LubOlimex]

The combo will probably not work out-of-the-box. There is a hardware compatibility issue, SHIELD-LCD-16x2 uses 3.3V level I2C while the levels of the new UNO board are 5V. This means 3.3V I2C would meet 5V I2C which might be a problem for proper communication. This can be resolved if level translators are installed on the I2C line. There is a ton of information online about how you can translate 3.3V I2C and 5V I2C since it is a commonly encountered issue.

Maybe check this blog post on how UNO R4 WiFi can achieve 3.3V shield compatibility:

https://community.element14.com/products/arduino/arduino-projects/b/blog/posts/modifying-the-arduino-uno-r4-making-it-3-3v-friendly

About the software, it should work fine without changes.

Alternatively either use shield that has 5V levels for communication or use Arduino board that has 3.3V levels (you can tell if main chip is powered by 3.3V or if there are build-in translators on the communication lines).