ESP32-C3 0.42" OLED board

The ESP32-C3 0.42" OLED board - sold as HW-675, by 01Space, and under a dozen no-name labels - is a thumb-sized ESP32-C3 with a 72×40 monochrome SSD1306 OLED soldered on. It is the smallest display FrameOS drives, and the cheapest way to try a microcontroller frame.

The C3 has no PSRAM, which is not enough for an on-device renderer - so FrameOS runs it as a thin client: your backend renders the scene and the device draws the finished bitmap. The backend has to be reachable when the frame renders, and FrameOS Cloud can't manage it. Everything else - scenes, apps, schedules, state fields - works the same way as on an ESP32-S3 frame.

Needs FrameOS 2026.9.10 or newer.

Setup

1. In the FrameOS backend, create a frame with Flash embedded device.
2. Choose ESP32-C3, select the ESP32-C3 0.42" OLED dev board preset, and enter your WiFi details.
3. Flash it over USB from the browser - the backend writes the release image for the board and sets it up as this frame.
4. Install scenes as usual. At 72×40 a clock, a number or a short line of text is about what fits.

The board has 4 MB of flash, so it uses the single-slot layout with no OTA partition: firmware updates go over USB.

Pin map

The BOOT button is registered as a GPIO button and can trigger events in your scenes.

Status

🟢 Confirmed working - a thin-client render at 72×40 was verified end to end on the board.