I have created a simple font for the X9 OLED display and used it to demonstrate text communication over serial Bluetooth using my Android phone. The BLE_CHAT example will display input from the Nordic phone app on the X9 display. If "red", "blue", "green", "yellow", or "purple" is sent, the message will be displayed in the corresponding color and a custom reply will be sent from the X9 activity tracker to the phone app.

I have also included a simple sketch demonstrating the super simple font.

All files for examples can be found in the GitHub repository, including required libraries and application hex files which I compiled myself. If you have a hacked X9 you can immediately load my compiled application to quickly check out the demo. I am adding the actual example sketches to the hackaday.io project files as well.

GitHub repository file directory:

nRF5x-device-reverse-engineering --> X9-nrf52832-activity-tracker --> Firmware --> examples --> nrf52_X9Project_BLE_CHAT
nRF5x-device-reverse-engineering --> X9-nrf52832-activity-tracker --> Firmware --> examples --> nrf52_X9Project_ALPHABET

Nordic UART Bluetooth Serial app: https://play.google.com/store/apps/details?id=com.nordicsemi.nrfUARTv2