Control your LEGO® Technic 42065 RC Tracked Racer with your Smartphone instead of using the included RC.

• Use a Progressive Web App as controller. Add it without further installation to your homescreen.
• Use Web standard communication with WebSockets
• Use cheap hardware components

• 42065 RC Tracked Racer
• A LEGO® Power Functions extension wire [8886]
• Amica NodeMCU ESP8266 - Important note: Not all ESP8266 development boards are compatible with the offered motor shields. Especially the sizing of the LoLin NodeMCU V3 doesn't fit together.
• ESP8266 NodeMcu V2 Motor Shield Board
• An elastic band to tie up NodeMCU and MotorShield the easy way with LEGO® bricks
• A bunch of wires

Plain LEGO® Technic 42065 chassis:

Assembled ESP8266 + Motorshield + LEGO® parts:

Details of ESP8266 + Motorshield + LEGO® parts:

You find further details of wiring LEGO® Power Functions for example here.

TODO further details

I tried various controller versions with the idea of using motion control abilities of my smartphone to control the vehicle:

• JSFiddle - First version inspired by Android Remote Controller

• JSFiddle - Adapted second version

Technically motion control works perfectly. - But in practise it was very unhandy for controlling the vehicle.

Finally the winner looks plain simpler:

• JSFiddle - Latest JSFiddle Version

Prerequisition: Polymer CLI

1. Install all dependencies - Go to folder tracked-racer-app:

$ polymer install

2. Test app locally in your browser.

$ polymer serve --open

Note: By design this app runs locally on ESP8266 and depends on a WebSocket served by the WebServer of the ESP. For production adjust the WS endpoint.

3. Prepare for production

$ polymer build

4. Upload app to ESP8266

Finally upload app from ESP8266/data/www folder to your ESP8266. Go to Arduino IDE Tools > ESP8266 Sketch Data Upload

Note: Close Serial Monitor of Arduino IDE before uploading data. Otherwise upload will interrupt.

Load sketch ESP8266.ino from ESP8266 folder in Arduino IDE.

Verify dependencies:

• #include <Esp8266Utils.h>
• #include <Log4Esp.h>

You can manage your additional includes by Arduino IDE Sketch > Include Library > Manage Libraries or you checkout dependencies yourself by git clone in your library folder of your Arduino sketchbook location.

Using git allows you to easily update all libraries at once:

ls | xargs -I{} git -C {} pull

With all dependencies provided the code should compile and is ready for upload.

5. Browse to https://esp8266.local/ to load the app.