A custom remote control for the Lego duplo 10427 train, built with a Seeed Studio XIAO ESP32S3 microcontroller. Designed for and tested with the LEGO DUPLO Train set 10427. Connects to the train over BLE using raw NimBLE and the LEGO Wireless Protocol 3 (LWP3).
- Board: Seeed Studio XIAO ESP32S3
- Potentiometer on GPIO2 (D1) for variable speed control
- 4 push buttons (active low, using internal pull-ups):
| GPIO | Pin | Function |
|---|---|---|
| 3 | D2 | Water/action sound cycle |
| 4 | D3 | Horn |
| 5 | D4 | Stop (brake) |
| 6 | D5 | LED color cycle |
- Variable speed — potentiometer maps linearly to 0-100% forward or backward, with a 15% deadband around center for stop
- 11 LED colors — cycle through off, white, green, yellow, light blue, dark blue, purple, purple pink, light pink, red pink, red
- 7 action sounds — cycle through recorded sound, cat, nothing, beach, rain, birthday, night
- Horn — plays the train horn sound
- Stop button — immediately stops the motor
- Auto-reconnect — automatically scans and reconnects when the train is turned off and back on
- Debounced buttons — using the Bounce2 library
Requires PlatformIO.
# Compile
pio run
# Upload to board
pio run -t upload
# Serial monitor
pio device monitor- NimBLE-Arduino 2.x — BLE stack
- Bounce2 — button debouncing
Pin assignments, potentiometer deadband, speed limits, and timing are all configurable in config.h.
Communicates with the Duplo Train Hub using raw LEGO Wireless Protocol 3 (LWP3) packets over BLE:
- Service UUID:
00001623-1212-efde-1623-785feabcd123 - Characteristic UUID:
00001624-1212-efde-1623-785feabcd123 - Motor packet format (11 bytes):
0B 00 81 34 11 51 01 [CMD] 01 [SPEED] 00- CMD:
01=forward,02=backward,03=stop,04=LED,06=action,07=horn
- CMD:
This project is based on the excellent work by drndos and his duplo-train-controller. Many thanks for figuring out the BLE protocol, the raw LWP3 packet format, and providing a working NimBLE implementation that made this project possible!