DragyDash ESP32

Experimental LilyGO T-Display-S3 firmware for showing live Dragy Pro speed and GNSS quality over Bluetooth LE.

The display is intentionally simple: large live speed on every page, with the smaller right-side metrics paginated by the board buttons.

Unofficial project: DragyDash ESP32 is not affiliated with, endorsed by, or supported by Dragy or LilyGO. The Dragy BLE behavior is based on limited hands-on testing and may vary by device or firmware version.

Display Pages

All values are metric only.

• Page 1: live speed, 5 km average, satellites, horizontal accuracy.
• Page 2: live speed, 1 km / 5 km / 10 km rolling averages.
• Page 3: live speed, peak speed, distance, altitude.

The firmware deliberately does not include 0-60 timing, 0-100 timing, lateral G, longitudinal G, imperial units, Wi-Fi, SD card logging, or settings screens.

Controls

• Quick left button tap: previous page.
• Quick right button tap: next page.
• Long left button: reset in-memory stats, including averages, peak speed, and distance.
• Long right button: pause BLE scanning/disconnect; long right again resumes scanning.
• Hold both buttons: cycle display brightness through dim, medium, and high.

Controls are RAM-only. Power cycling also resets run stats and resumes scanning.

What It Implements

• PlatformIO firmware for lilygo-t-display-s3.
• ST7789 170x320 display via TFT_eSPI.
• BLE client using NimBLE-Arduino.
• Dragy-style discovery by FD00 service or DRG* name.
• FD03 challenge response: [a, b, a XOR b, a AND b].
• FD02 notification stream reassembly for UBX NAV-PVT-like packets.
• NAV-PVT decoding for fix quality, satellites, altitude, horizontal accuracy, ground speed, and heading.
• FD04 battery percentage parsing from observed status packets.
• Distance-based rolling averages with a compact 15 km segment buffer.
• No-fix samples excluded from distance, peak speed, and rolling averages.
• Connection/fix status states: SCAN, WAIT GPS, BUSY?, STREAM, and PAUSED.

Documentation

• Firmware behavior
• Hardware assumptions
• Build and flash commands
• Dragy BLE protocol notes

Build

Requirements:

• Python 3
• PlatformIO Core

Project-local setup:

git clone https://github.com/jremick/dragy-dash-esp32.git
cd dragy-dash-esp32
python3 -m venv .venv
.venv/bin/python -m pip install --upgrade platformio
.venv/bin/pio run

If PlatformIO is already installed globally:

git clone https://github.com/jremick/dragy-dash-esp32.git
cd dragy-dash-esp32
pio run

Flash

Confirm the serial port before flashing:

.venv/bin/pio device list

Flash to the confirmed ESP32-S3 port:

.venv/bin/pio run --target upload --upload-port <PORT>

Open a serial monitor:

.venv/bin/pio device monitor --port <PORT> --baud 115200

Do not flash unless the selected port is clearly the intended LilyGO T-Display-S3.

Hardware Notes

Target board:

• LilyGO T-Display-S3
• ESP32-S3
• ST7789 170x320 display
• two physical buttons

The current pin assumptions are documented in Hardware assumptions. Verify your board revision before relying on the pin map.

Runtime Expectations

The ESP32 connects as a BLE central. If the official Dragy app or the iOS DragyDash app is already connected, the Dragy may reject or stall the ESP32 connection. The firmware shows BUSY? or STREAM when it connects but telemetry does not start or later stops.

Safety

Do not interact with the display while driving. Mount the display securely, obey local road laws, and verify speed against safe/legal instrumentation before relying on any displayed value.

This firmware is experimental and should not be used as the sole source of speed, vehicle state, or compliance information.

Privacy

Public issues should not include raw BLE captures, full Dragy identifiers, route traces, or serial logs that expose a unique device. Use redacted examples only. See SECURITY.md.

License

Apache License 2.0.