NotifyBridge - LoPy4 + PyTrack

Turn a LoPy4 + PyTrack GPS tracker into a push notification device with NotifyBridge.

Platform: Espressif ESP32 · Board: lopy4 · Framework: Arduino (ESP32 core)

Runs on a Pycom LoPy4 module mounted on the PyTrack v2.0 expansion board.

Sensors

Sensor	Library	Usage
L76GNSS (GPS)	TinyGPSPlus	Position (lat/lon), speed, altitude, satellite count
LIS2HH12 (accel)	rhio-LIS2HH12	Acceleration (g), earthquake detection

The L76GNSS communicates over I2C (address 0x10) rather than UART. GPS time is used to sync the ESP32 RTC via settimeofday() on first valid fix; heartbeat timestamps switch from uptime to wall-clock UTC once synced.

Alert Thresholds

Event	Trigger	Priority	Cooldown
High speed	GPS speed > 120 km/h	2	5 min
Earthquake	3+ consecutive accel deviation > 0.2 g from 1 g	2	5 min
Heartbeat	Every 30 minutes — includes RSSI, sensor snapshot, and position drift	−1	—

• Button on GPIO 37 (PyTrack P14) — sends a priority-1 notification with timestamp and sensor snapshot on press
• WS2812B RGB LED on GPIO 0 — IDLE state flashes green when GPS has a fix, blue while waiting for fix
• Position drift tracking — the heartbeat reports maximum drift (metres) and sample count since the last heartbeat
• Uses the native ESP32 HTTPClient library for HTTPS POST

Prerequisites

• PlatformIO (CLI or VS Code extension)
• A Mindeon NotifyBridge account with an API token and user key

Quick Start

git clone https://github.com/mindeon/NotifyBridge-LoPy-PyTrack.git
cd NotifyBridge-LoPy-PyTrack

Configure your credentials in src/main.cpp:

#define WIFI_SSID      "YOUR_WIFI_SSID"
#define WIFI_PASSWORD  "YOUR_WIFI_PASSWORD"

#define NB_API_TOKEN   "YOUR_API_TOKEN"
#define NB_USER_KEY    "YOUR_USER_KEY"
#define NB_DEVICE_CODE "YOUR_DEVICE_CODE"

Build and upload:

pio run --target upload

LED State Machine

State	Pattern	Meaning
CONNECTING	Fast 100 ms toggle	Joining WiFi
IDLE	50 ms flash every 3 s	Connected, waiting
SENDING	3 rapid 50 ms blinks	Sending notification
DISCONNECTED	Slow 500 ms toggle	WiFi lost

Notification Delivery

HTTP POST to https://notifybridge.mindeon.net/v1/messages/send with JSON payload:

{
  "api_token": "YOUR_API_TOKEN",
  "user_key": "YOUR_USER_KEY",
  "device_code": "YOUR_DEVICE_CODE",
  "message": "Notification text",
  "priority": 1
}

Failed requests are retried with exponential backoff: 2 s initial delay, doubling up to 60 s, for a maximum of 5 attempts.

Priority	Meaning
−1	Background / heartbeat
1	User-triggered (button press)
2	System alert (WiFi restored, sensor event)

NotifyBridge

This project sends push notifications via NotifyBridge, a cloud notification service for embedded and IoT projects — no Firebase SDK, no mobile development, no notification backend, just an HTTPS request.

• 📖 REST API
• 📚 Full developer guide — setting up your account, creating devices, claiming, groups
• 🧭 Other supported devices

License

See LICENSE for details.