ESP32 Web Bluetooth RC Car 🚗

An ESP32 RC car controlled from a browser via Web Bluetooth. Just open the HTML, connect via Bluetooth and drive.

Here's the current look of the car:

📡 Enabling Web Bluetooth

Web Bluetooth is what lets the browser talk directly to the ESP32. Here's what you need:

✅ Works out of the box:

• Chrome or Edge on Android
• Chrome or Edge on Windows / macOS / Linux

⚠️ Needs a flag enabled:

• Brave: brave://flags → enable "Web Bluetooth API"
• Chrome: chrome://flags → enable "Web Bluetooth"

❌ Doesn't work:

• Safari on iOS → use Bluefy or WebBLE from the App Store
• Firefox → no support at all

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🧰 Components

Brains

• ESP32 WEMOS LOLIN32 Lite (CH340C chip)
• TC1508A Dual H-Bridge Motor Driver Module (sold as ,,MINI L298N", but with the TC1508A chip, not an actual L298N)

Muscles

• 2x TT Gearbox DC Motor (3V–6V, 1:48 gear ratio)
• 2x 5mm Yellow LED
• 2x 220Ω Resistor (for the LEDs)

Power/Charging

• 3.7V 1S Lithium-Polymer Battery (Original: 802060-1000mAh, died. Replaced with: --)
• TP4056 Lithium Charger Module (with DW01HA + 8205A protection, USB Type-C)
• MT3608 DC-DC Boost Converter (Step-Up, set to output 5V)
• LM2596 DC-DC Buck Converter (Step-Down, set to output 3.3V)
• 2x 2-Pin Rocker Switch (SPST) (one for the charger circuit, one for the main motor+led circuit)

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Motors, charger and rest of logic get separate power, but there's one shared ground.

Ground (GND): Every - wire in the car goes to one common junction.

Pins used:

Function	GPIO
Motor A	13, 26
Motor B	33, 4
LEDs	18, 23

💻 Setup

ESP32 (Arduino IDE):

1. Board: WEMOS LOLIN32 Lite w/ CH340C chip
2. Upload speed: 115200 (921600 fails with a scary flash error)
3. Libraries: BLEDevice, BLEServer, BLEUtils, BLE2902
4. Upload the .ino to the board

Controller:

1. Open controller.html in Chrome or Edge
2. Click CONNECT TO CAR
3. Pick ESP32_RC_Car from the browser popup

🎮 Driving

1. Flip Switch 2 (car circuit) ON. Leave Switch 1 (charger) OFF.
2. Connect via the web page.
3. GAS / REVERSE / LEFT / RIGHT / STOP / LIGHTS

To charge:

1. Flip Switch 2 (car) OFF.
2. Flip Switch 1 (charger) ON.
3. Plug in USB to the TP4056.
4. When done, unplug USB, flip Switch 1 OFF.

⚠️ Lessons Learned the Hard Way

• Don't connect USB and battery at the same time. Pick one.
• Set LM2596 to exactly 3.30V before wiring it to the ESP32. Not 3.5V or anything "close enough."
• Battery → MT3608 (5V) → LM2596 (3.3V) because the buck converter can't lower a voltage less than 5V, so we need to first increase the 3.7V to 5V, then reduce it to 3.3V.
• Don't charge while driving. TP4056 has no load sharing.
• Web Bluetooth ≠ OS Bluetooth pairing. Do NOT pair through phone/laptop settings, just use the button ,,CONNECT TO CAR" on the web page and pair through via Web Bluetooth. If you already paired via OS, forget it first.
• Motors without capacitors can work fine. (add them only if Bluetooth drops out under load)

🛠️ Quick Troubleshooting

Problem	Fix
"Flash chip connection" error	Upload speed → 115200
Won't boot on battery, works on USB	Check common ground, verify 3.30V under load, press RST once and wait 5s
Motors twitch and everything dies	Battery sag or DW01 tripping

🪦 Casualties

• 1x 1000mAh LiPo (802060) — Seriously discharged during testing and never recovered. Would charge to 4.1V in less than 10 min and drop back to 3.1V the second you unplugged it.
• 1x TC1508A Motor Driver — Died suddenly mid-project. Suddenly stopped responding on Motor A, onnly worked for Motor B. Suspect a voltage spike during the LiPo's final death throes. Replaced with an identical unit.
• 1x GPIO 27 — Killed during a soldering operation with a bad batch of solder. Moved Motor B over to GPIO 33 instead.

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📜 Status

Working. Tight turning, stable Bluetooth, headlights toggle. Future upgrades: better design

A lot more parts died than planned. Soldering was nearly impossible at times.