tepra-lite-esp32

MicroPython module to communicate with KING JIM TEPRA Lite LR30

Preface

This is a reverse-engineered module to communicate with KING JIM TEPRA Lite LR30. A REST API server implemented in ESP32 + MicroPython translates the image you requested into Bluetooth Low Energy communication.

client directory has an implementation of CLI to send requests to it.

Requirements

ESP32
- Developed on ESP-WROOM-32
- Any ESP32 modules should be capable of running this
Latest stable MicroPython
- Developed on esp32-20210418-v1.15.bin

Installing

Fill the SSID and PSK in config.json.

Put all files into your ESP32 with adafruit-ampy.

export PORT=/path/to/the/usb/serial
ampy --port ${PORT} put ble_advertising.py
ampy --port ${PORT} put bluetooth.pyi
ampy --port ${PORT} put config.json
ampy --port ${PORT} put main.py
ampy --port ${PORT} put nanoweb
ampy --port ${PORT} put tepra.py
ampy --port ${PORT} put time.pyi
ampy --port ${PORT} put typ1ng.py
ampy --port ${PORT} put wifi.py

The main function will be invoked on boot automatically.

How to print

Install tepra-lite-esp32 into your ESP32.
See client for a CLI and install it.
Turn on your TEPRA Lite LR30.
Turn on your ESP32.
- It will connect to the AP you configured in config.json.
- Then it discovers an advertising LR30.
- After the connection process, it will print like [12.48] Launching the Tepra API and you're ready to proceed.
Send requests to the ESP32 with the client.
- See the README.md for the usage.

Why ESP32 + MicroPython?

Why I wrote this module in MicroPython is because it enriches the time of coding on microcontrollers. The simple and easy-to-use API of ubluetooth is also a prominently good point. It let me focus on high-level behavior of BLE stack and may help people who are interested in reverse engineering and re-implementing BLE communication.

The nature of import will also work nicely when you prototype your project that connects something and TEPRA Lite. Import tepra on the REPL and try communicating with it step-by-step.

And here's another reason: preventing nightmares of Bluetooth stacks on PC, for example, Bluez. Bluez has a Python binding that is prone to crash and raise exceptions everywhere. While there are some choices like Bleak that works multi-OS, I didn't choose this. Resetting entire stack including the physical BT module is hard without rebooting. When it comes to ESP32, it's super easy; you just have to push the RESET button on the module. This literally resets everything on ESP32 and removes any side effects until then.