Ubiquiti's Flex Mini Runs on an Undocumented Nuvoton Chip
A firmware dump plus the debug port's identity register name the chip in Ubiquiti's USW Flex Mini, and Zephyr's thin support for it is what blocks a fresh firmware.
ESP32 showed up in the firmware filenames of Ubiquiti’s small switches, and the teardown that followed ended at the Flex Mini. Its MCU carries only a Nuvoton marking — UB10, or U810 — that appears nowhere online except one blog post. The switch IC is an RTL8367RB, whose public datasheet says only “internal”.
The dump came over SWD with a hacked-together OpenOCD and gdb’s dump binary memory. Pin mapping pointed at an M467SJHAN; its EMAC registers did not match the reference manual. The M487SIDAE did, and the debug port’s DPIDR confirmed a Cortex-M4. Zephyr’s support for that MCU is thin, and the effort has moved to the USW-Ultra for now.
I have used a Pico as a debug probe and felt clever about it; pulling a chip’s identity off its debug port is the step I would have walked past. Skip it if you want working ports and no interest in the silicon. The devicetree is the durable output; follow that board file.