One other use-case for my old Nextion/TJC screens is to turn the device into a Serial Debug Monitor. It will just spit out the serial buffer to the screen, so you can monitor what’s being sent. For example when booting an MCU:
The UI runs standalone on the Nextion/TJC screen, so no MCU is needed. The code runs on the display. Just hook it up to a serial interface and watch the output scroll by…
There is even an onscreen keyboard to send commands over serial too:
