Replaced a dead fan-controller MCU on a dual V100 board with an RP2040, Claude doing the reverse engineering

Dual Tesla V100 carrier board fan controller: preview from notes.alelec.net — Image: notes.alelec.net

What was done

Claude Code scanned the board to find the I2C bus and LM75-style temperature sensors, traced the fan PWM lines, and wrote MicroPython control firmware; a 4-hour full-load run held both GPUs below throttling.

Where the human stepped in

The author did the soldering and wiring and used Gemini only to sanity-check that the sensor was digital I2C. A leftover boot.py on the board crashed boot until removed.

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Firmware and hardwareWorks

Target: Dual Tesla V100 carrier board fan controller

Replaced a dead fan-controller MCU on a dual V100 board with an RP2040, Claude doing the reverse engineering

by Andrew LeechRead the writeup

What was done

Where the human stepped in

The author did the soldering and wiring and used Gemini only to sanity-check that the sensor was digital I2C. A leftover boot.py on the board crashed boot until removed.