Rust firmware replacing only the original Elgato Key Light's Realtek controller with an ESP32-C3_MINI_V1. It retains the PCA9635, stock LED driver circuitry, LEDs, and power supply. Matter over Wi-Fi provides local Apple Home control.
Each lamp exposes one Matter Color Temperature Light with power, brightness, and white-temperature controls. Home's 1% through 100% brightness maps to stock nominal 1% through 10%; Home 100% is the selected low-light ceiling. The initial level is about Home 22%, reproducing the former stock nominal 3% output. Temperature spans 143 through 344 mired (about 6993 through 2907 K).
Pair two lamps separately, then group them in Apple Home to control brightness and temperature together. The former 3300 K and 5000 K choices can be Home scenes. Grouping does not guarantee simultaneous output. Stock firmware evidence defines PCA commands, not measured brightness or Kelvin, and low-output steps are limited by eight-bit PWM quantization.
On September 29, Michael reports that both closed-up lamps work well and have a solid connection without external antennas. This is his current experience, not a long-term reliability result. Bench probing is complete. A resistor trial visibly reduced the faint orange panel glow while Off, but residual glow remains. Whether it disappears after longer Off is unknown. Its electrical cause remains under investigation; zero PWM does not establish optical darkness.
Board A runs 0.1.4; board B remains on 0.1.3. Version 0.1.4 adds 400 ms eased power, brightness and temperature transitions while Home continues to report selected targets immediately. Output-frame fades reach zero; intermediate frames never write flash. Visual fades and detailed loaded startup remain unverified. Low-output steps remain limited by the PCA's 8-bit resolution. Firmware 0.1.5 adds Matter-delivered OTA updates with bootloader rollback. It requires one USB migration per board, and neither board has had it yet. See development. The validation record separates installed-image results, user observations and remaining checks.
The Rust application targets esp32c3. The spec records the
single-light control contract. Build results and pending checks are recorded in
software validation.
- Installed board, five-wire map, measurements, and limits
- Initial bench power, chip inspection, flashing, and probing
- Development and USB instructions
- Physical validation record
- Off-glow diagnosis and next-opening fix plan
The controller uses the retained PCA9635 over I²C. It does not lift PCA output legs or add level translators or output interlocks. GPIO4/5/6 provide SDA/SCL/OE; the board takes power directly from the lamp's measured 3.37 V rail. With lamp wiring attached, USB must block VBUS/5 V while retaining data and ground. Ordinary powered USB requires disconnecting all five lamp wires first.
sh scripts/check.sh
sh scripts/check-firmware.sh
python3 scripts/device.py --listfirmware/core is dependency-free no_std state and PCA9635 logic;
firmware/cli simulates it without hardware. firmware/app has separate real
and bench C3 images. Host tests establish software behavior
only, not correct wiring, safe startup, physical light output, or real-network
recovery.
See requirements, research, and stock firmware evidence. Original photos and datasheets remain in docs/references.
