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LMKS V1 Light Meter
I built LMKS V1 to shrink my earlier light meter into a compact custom PCB and enclosure that can sit directly on a camera hot shoe.
Background
I started this project because I wanted to miniaturize the light meter I built in June 2025. In KiCad, I laid out a custom 2 layer PCB in a 35×35 mm footprint. The board is centered around an ESP32-C3 with mostly SMD parts, including a BH1750 light sensor and SSD1306 OLED. I had to make custom footprints for several components to fit everything cleanly in that small area.
Once the board was finalized, I designed the enclosure in Solidworks around the real hardware stack. I built custom toggles and rotary encoder attachments so the mechanical controls lined up correctly with the PCB components. The final result is a smaller and more portable light meter that fits on the hot shoe of a film camera.
Technical architecture
V1 combines a compact custom PCB with a SolidWorks enclosure, with BH1750 sensing, SSD1306 readout, and USB C connectivity. Controls use a rotary encoder, tactile switches, and printed toggle extensions aligned to the board.
Core electronics
- Microcontroller: ESP32-C3
- Light sensor: BH1750 digital ambient light sensor
- Display: SSD1306 0.91" monochromatic OLED
- PCB: Custom 2-layer FR4
- Connectivity: USB-C 16-pin
Control & interface
- Rotary encoder: 1× incremental rotary encoder
- Buttons: SMD tactile switches
- Custom toggles: 3D printed mechanical toggle extensions
Roadmap
LMKS V2 is planned for May 2026 with lower power draw, improved light sensing, and a smaller footprint. The update targets an STM32L072x8, a 350mAh LiPo, a VEML7700 lux sensor, and an Alps navigation wheel. I plan to prepare this version for market release and certification in the United States.
- MCU: STM32L072x8 (lower power consumption)
- Battery: 350mAh LiPo
- Light sensor: VEML7700 lux sensor
- Navigation: Alps navigation wheel