🧭 BLE HUD Navigation — LilyGO T-Display-S3

A pocket-sized Bluetooth Heads-Up Display that mirrors your phone's turn-by-turn navigation — directions, distance, speed and speed limits — onto a crisp ESP32-S3 screen on your dashboard.

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🚀 Overview

BLE HUD turns a LilyGO T-Display-S3 into a wireless Heads-Up Display for car navigation. It connects over Bluetooth Low Energy to a navigation app on your phone and shows the next maneuver in large, glanceable graphics right in your line of sight — no need to look down at your phone while driving.

It's cheap (~€15 board), runs on a single ESP32-S3, and needs no internet of its own — all the routing happens on your phone.

This project is adapted for the LilyGO T-Display-S3 and builds on the original BLE-HUD-navigation-ESP32 by Alexander Lavrushko.

The HUD (right) mirroring the next turn, distance and speed limit from the phone (left).

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✨ Features

• 🧭 Turn-by-turn directions — large arrow icons for every maneuver
• 📏 Distance to next turn — live countdown to the upcoming maneuver
• 🚦 Speed & speed-limit display — current speed and the active limit
• 🛣️ Lane guidance — lane-assist graphics for complex junctions
• 🔌 Connection-aware states — startup, disconnected, no route, navigating, recalculating
• 🎬 Startup animation — clean boot splash with progress bar
• 🔋 Battery voltage monitoring — optional, for portable/battery builds
• 😴 Deep sleep — button-triggered low-power mode to save energy
• 📱 Works with Sygic GPS (iOS) over standard BLE GATT

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🛠 Hardware

Component	Details
Board	LilyGO T-Display-S3 (ESP32-S3)
Display	Integrated 1.9" ST7789, 320×170, full colour
Connectivity	Bluetooth Low Energy (built into the ESP32-S3)
Power	USB-C, or a Li-Po battery on the onboard connector
Optional	Voltage divider for battery-level monitoring

🛒 Where to buy the board

• AliExpress (affiliate link)
• Alibaba (affiliate link)

🔘 Buttons

Button	GPIO	Action
Left	IO0	Long press → enter deep sleep (press again to wake)
Right	IO35	Toggle battery voltage display

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📲 Phone app — Sygic GPS (iOS)

The HUD currently receives data from Sygic GPS Navigation & Maps: Download on the App Store.

Enable the hidden BLE HUD feature

1. Open Sygic → Menu → Settings → Info → About
2. Tap 3 times on any item to unlock the hidden menu
3. Go to About → BLE HUD → Start
4. Grant Bluetooth permission

The app will then find and connect to the ESP32 automatically.

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🔧 Build & flash

Prerequisites

• Arduino IDE with ESP32 board support (install guide)
• This repository (clone it or download the src/ folder)

Required libraries

Library	Where to get it
TFT_eSPI	Library Manager — must be configured for the T-Display-S3 (see below)
Button2	Library Manager
BLEDevice / BLEServer / BLEUtils / BLE2902	Bundled with the ESP32 Arduino core

Configure TFT_eSPI for the T-Display-S3

Use the display config from the official LilyGO repo: Xinyuan-LilyGO/T-Display-S3. Apply User_Setups/SetupXX_TDisplay_S3.h (or edit User_Setup.h) so TFT_eSPI targets the onboard ST7789. This is the #1 cause of a blank/garbled screen.

Flash

1. Board: ESP32S3 Dev Module (or LilyGo T-Display-S3)
2. Select the correct USB port
3. Open src/BLEHUDNaviESP32TDislpays3.ino and Upload

💡 If the board isn't detected, hold BOOT while plugging in the USB-C cable to force download mode.

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📡 BLE communication protocol

The ESP32 advertises a GATT service and expects navigation packets in this format:

[1, <speed>, <direction>, <message>]

Field	Type	Description
speed	uint8	Current speed (0–255 km/h)
direction	enum	Maneuver type — see src/DataConstants.h
message	string	Null-terminated street/instruction text

GATT	UUID
Service	DD3F0AD1-6239-4E1F-81F1-91F6C9F01D86
Indicate (notify)	DD3F0AD2-6239-4E1F-81F1-91F6C9F01D86
Write	DD3F0AD3-6239-4E1F-81F1-91F6C9F01D86

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💻 Usage

1. Power on the device — it shows the startup animation, then "waiting for connection".
2. Start navigation in Sygic and enable the BLE HUD feature (steps above).
3. Once connected, the HUD shows the next direction, distance, speed and speed limit automatically.
4. Long-press the left button to put the device into deep sleep.

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🗂️ Project structure

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├── src/
│   ├── BLEHUDNaviESP32TDislpays3.ino   # Main sketch (BLE server, display state machine)
│   ├── DataConstants.h                 # Direction enums & shared constants
│   ├── ImagesDirections.h              # Turn-arrow bitmaps
│   ├── ImagesLanes.h                   # Lane-assist bitmaps
│   ├── ImagesOther.h                   # UI/status bitmaps
│   └── VoltageMeasurement.h            # Optional battery-voltage helper
├── image/                              # Demo GIF & photos
└── README.md

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🧯 Troubleshooting

Symptom	Fix
Blank or garbled screen	TFT_eSPI not configured for the T-Display-S3 — apply the LilyGO setup file
Board not detected	Hold BOOT while connecting USB-C to enter download mode
Phone won't connect	Re-enable the hidden BLE HUD menu in Sygic and toggle Bluetooth
Compile error on BLE headers	Make sure the ESP32 Arduino core is installed and selected

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🔮 Roadmap ideas

• Android navigation app support
• Configurable units (km/h ↔ mph)
• Adjustable brightness / auto-dimming
• 3D-printed dashboard mount

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🙌 Acknowledgements

• Alexander Lavrushko — the original BLE-HUD-navigation-ESP32 codebase this project is based on.
• Xinyuan-LilyGO — T-Display-S3 hardware & display configuration.

If this project is useful to you, please consider giving it a ⭐ — it really helps others find it!

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📜 License

Released under the MIT License.