Running a custom firmware based on RIOT-OS on an IKEA TRÅDFRI light bulb (in this case, the GU-10 bulb).
The light bulb contains a Silicon Labs EFR32MG1P microcontroller, of which the debug pins are accessible. This video demonstrates that it is possible to flash another firmware onto the chip.
Current functionality is limited, as the video only shows how to toggle the LEDs using the shell.
The additional PCB is a UART isolator, so I don’t fry my machine.
More info can be found on