Droidputter

Plug an ESP32-S3 into an Android phone and the phone becomes the Cardputer.

Open-source Cardputer apps are rebuilt on demand from GitHub against a display and keyboard shim, flashed from the phone, mirrored on the phone, and driven from the phone's keyboard and GPS. The ESP32-S3 runs the app; the phone adds screen, keys, location, and a flasher. No display is needed on the board.

Features

App mirroring

- Any open-source Cardputer app, rebuilt unchanged against a patched M5GFX and M5Cardputer shim, becomes a phone app. - Every pixel write is sent over the ESP32-S3's native USB, and the phone's keys and GPS are merged into the app's keyboard and serial input.

Build on demand

- Builds happen on GitHub Actions through a small proxy. - Pick a recipe, paste any GitHub repository, or use a LauncherHub prebuilt. - A warm build takes about 2 minutes, a cold build about 4 minutes. - A build the proxy already has for the same repository, ref, target, and shim (under 24 hours old) is fetched instantly.

Flash from the phone

- Downloads and verifies the firmware, enters the ESP32-S3 ROM bootloader, writes all parts, and MD5-verifies each region before resetting. - Reset-to-verified takes 8 to 15 seconds depending on firmware size. - The link reconnects 190 to 330 ms after the reset.

Use it

- The ESP32's screen becomes the phone's screen. - The soft keyboard is the Cardputer's own 4x14 matrix, including fn and shift layers. - A Bluetooth or USB keyboard attached to the phone also works. - GPS: the phone's NMEA sentences reach the app like a serial GPS, with the link's foreground service keeping them flowing with the screen off.

Supported targets

- Bare ESP32-S3 devkit, with the phone as the only screen. - M5Stack Cardputer ADV, where the board's own TFT is also updated.

Verdicts

- 20 seconds after a flash, the app decides works or broken from the link evidence, or asks for one tap. - A tap files a GitHub issue through the proxy, which is folded into a shared verdicts file every phone reads back.

Requirements

- Android 8.0 (API 26) or newer with USB-OTG host support - An ESP32-S3 board (the app refuses anything else) - An OTG cable and a known-good data cable - Use the board's native USB port, not a UART or COM bridge port

Notes

- A board still running UiFlow2 or MicroPython needs its BOOT button held while replugging on the first flash, because a software CDC ignores the phone's reset signal. Once a Droidputter build is on the board, the phone resets it alone. - Debug and release APKs are signed with different keys, so uninstall one before installing the other.

Disclaimer

Droidputter is an independent community project by Felipe Cavalcanti. Cardputer, StickS3, and M5Burner are M5Stack names. It is not affiliated with M5Stack, Espressif, or any third-party service. The apps shown or supported by the catalog belong to their respective authors and keep their own licences. All trademarks belong to their respective owners.

License

MIT