Converting A CardKB Credit Card Sized Keyboard From I2C to UART

I wanted a small keyboard for use with some of my projects. I found a CardKB keyoard on M5Stack.com  that was almost what I wanted. It used an I2C interface, but I wanted one with a UART interface. It was pretty easy to modify the Arduino firmware to do that.  To find out more about this project and get the Arduino sketch, CLICK HERE.