key-right: an upgrade for the Elgato Key Light

Architecture & System Overview

The Elgato Key Light is a staple of modern streaming and video conferencing infrastructure, valued for its form factor and edge-lit diffusion. However, its closed-ecosystem firmware and proprietary control protocol restrict deeper integration into custom studio automation pipelines. The key-right project addresses this limitation by presenting a drop-in controller replacement that strips away the proprietary control stack in favor of an open, transparent architecture.

From a system architecture perspective, key-right intercepts the low-level power delivery and LED driver stages, decoupling the lighting hardware from manufacturer-dependent software. The system relies on a modular replacement board that interfaces directly with the original constant-current driver circuitry and power delivery rails. By replacing the stock microcontroller with an open-source alternative, the architecture enables direct integration into standard local automation frameworks, such as Home Assistant via MQTT or native ESPHome implementations, bypassing cloud dependencies and proprietary mobile applications.

Hardware Design & Component Selections

The hardware design of key-right centers around maintaining mechanical compatibility with the internal chassis of the Elgato Key Light while upgrading the processing and communication capabilities. The replacement PCB is engineered to mount directly onto the existing structural standoffs, utilizing the original thermal management pathways and connector pinouts where feasible.

Key component selections prioritize availability, community support, and robust peripheral sets: * Microcontroller Unit (MCU): An ESP-based module (such as an ESP32-C3 or ESP8266 variant) is typically selected for its integrated Wi-Fi and Bluetooth capabilities, low idle power consumption, and sufficient PWM hardware channels to independently drive the warm and cool LED arrays. * Power Regulation: The onboard power supply unit (PSU) of the Elgato Key Light provides a high-voltage direct current (DC) bus, which key-right steps down using a high-efficiency buck converter to supply clean 3.3V logic to the digital control plane. * PWM Gate Drivers / MOSFETs: To control the high-density surface-mount LEDs without thermal runaway, the design utilizes logic-level N-channel MOSFETs capable of handling the required current load. High-frequency PWM (typically above 20 kHz) is employed to eliminate visible flicker during high-speed video capture and to prevent audible coil whine from the inductive components.

Firmware Architecture & Protocols

The firmware architecture of key-right is built for deterministic lighting control and low-latency network responsiveness. Because the lighting unit is frequently deployed in professional video environments, firmware stability and smooth dimming curves are critical design parameters.

* Control Loop & Dimming Resolution: The firmware implements logarithmic or gamma-corrected PWM mapping. Human perception of brightness is non-linear; applying a direct linear mapping from 0 to 100% results in bunched steps at the lower end of the brightness scale. The firmware translates input values into a 10-bit or 12-bit PWM duty cycle, ensuring perceptual linearity across both color temperature (ranging from warm amber to cool daylight) and overall luminance. * Communication Protocols: Eschewing proprietary binary protocols, key-right natively supports standard Internet of Things (IoT) transport layers. When flashed with ESPHome, the device exposes native API endpoints and YAML-configurable entities. Alternatively, custom firmware builds implement lightweight MQTT clients with Last Will and Testament (LWT) configurations, ensuring state synchronization with home automation controllers in the event of network interruptions. Local fallback controls—such as physical buttons wired to General Purpose Input/Output (GPIO) pins with internal pull-ups—allow manual toggle and dimming adjustments directly on the chassis.

Limitations, Trade-offs & Builder Prerequisites

While key-right offers a significant functional upgrade, implementing this modification involves specific engineering trade-offs and safety considerations:

* Mains Voltage Exposure: The Elgato Key Light houses an integrated high-voltage AC-to-DC power supply internally. Builders modifying the hardware must exercise extreme caution. Working in close proximity to exposed AC mains wiring or primary-side bulk capacitors presents severe electrocution risks. Proper insulation, physical barrier placement, and adherence to safe electronics assembly practices are mandatory. * Thermal Management: The original enclosure is designed to dissipate heat generated by the stock LED arrays under specific thermal loads. Altering the driving frequency or driving the LEDs outside their original operational parameters can lead to accelerated junction temperature degradation. Builders must verify that MOSFET saturation is complete to minimize resistive heating on the replacement PCB. * Loss of Out-of-the-Box Proprietary Features: Flashing custom firmware permanently severs compatibility with Elgato’s Control Center software and Stream Deck plugins unless custom bridging scripts are written by the end-user. * Licensing: The project is distributed under an Open Hardware license, granting users the freedom to study, modify, and manufacture the hardware designs and associated firmware source files, provided attribution is maintained according to the terms of the specific repository release.