Seeking 4x4 keypad for Onion Omega 2 (hardware novice)

I have been an embedded programmer for decades, but only in large projects, and it might surprise you that most of the software guys never learn anything about hardware.

I prefer the Onion Omega 2 to the Raspberry Pi and would like to code a project which requires a 4x4 keypad, while at the same time using their display Hat shield thingy

The pin out for the GPIO is at

The forum post at says that
"The OLED uses I2C, so (as far as I am aware) the only pins you should need to connect are:


So, the rest would be free for the keypad. That post also recommends using their $5 proto expansion board (Sorry, the link is in acomment following this post, as new users are limited to 2 links)


  • which cheap 4x4 keypad can I use for a proof of concept?
  • how would I wire it?
  • can I do it without soldering?

Sorry to ask what is probably a very basic “hello world” type question, but that’s about the limit of my hardware ability :-)

Many thanks in advance for any help.

Here’s the link to the proto expansion -