Marph's Tracker

A small, battery-powered Wi-Fi/GNSS tracker based on the LilyGO T-SIM7080G-S3 and MicroPython.

Motivation

I want a theft protection for our new stroller.

Requirements:

• Small and mobile
• Cheap
• Can send from any location to a configurable endpoint
• Without vendor-lock (no app/registration)

Images

Tracker Assembled	Tracker in Case
Tracker in Stroller	Tracker in Traccar

Overview

• Hardware:
  • LILYGO T-SIM7080G-S3 including GNSS and LTE antenna
  • 18650 battery
  • IoT SIM card
• Location methods:
  • WiFi (+ cell data) -> BeaconDB
  • GNSS
• Cellular connectivity: LTE-M or NB-IoT

The tracker obtains the location based on GNSS or WIFI. This data is sent to a configurable URL. In my case, this is a ntfy instance. A custom script subscribes to the ntfy instance, converts the data and forwards it to a self-hosted Traccar server in my home lab.

Please check the documentation for setup instructions and further details:

• Quick start
• Software implementation details
• Battery life estimation
• Cost estimation
• Search for a good LTE-M or NB-IoT SIM card

Example Deployment

flowchart LR

    %% =========================================================
    %% DEVICE
    %% =========================================================
    subgraph DEVICE["📍 LILYGO T-SIM7080G"]
        direction TB

        TRACKER["Tracker"] --> WIFI_PATH["📶 WiFi path"]

        WIFI_PATH -->|"Configured home SSID detected"| WIFI_PASSWORD["WiFi password set?"]
        WIFI_PASSWORD -->|"No"| DONE["Cycle finished"]
        WIFI_PASSWORD -->|"Yes -> heartbeat"| WIFI["WiFi"]
        WIFI_PATH -->|"Enough APs detected"| CELLULAR["LTE-M / NB-IoT"]
        WIFI_PATH -->|"Too few APs"| GNSS_PATH["🛰️ GNSS path"]

        GNSS_PATH -->|"Fix -> Location"| CELLULAR
        GNSS_PATH -->|"No fix -> WiFi fallback or heartbeat"| CELLULAR
    end


    %% =========================================================
    %% PUBLIC NETWORK
    %% =========================================================
    subgraph PUBLIC["🌐 PUBLIC NETWORK"]
        NTFY["ntfy"]
        BEACON["BeaconDB\nWiFi geolocation"]
    end


    %% =========================================================
    %% HOME NETWORK
    %% =========================================================
    subgraph HOME["🏠 HOME NETWORK"]
        CONVERTER["Message Converter"]
        TRACCAR["Traccar Server"]
    end


    %% =========================================================
    %% CONNECTIONS
    %% =========================================================

    WIFI -->|"Publish"| NTFY
    CELLULAR -->|"Publish"| NTFY

    NTFY -->|"Subscribe"| CONVERTER

    CONVERTER -->|"WiFi AP lookup"| BEACON
    BEACON -->|"Location"| CONVERTER

    CONVERTER -->|"HTTP Request in OsmAnd format"| TRACCAR

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Abbreviations

Abbreviation	Description
AP	Access Point. I.e. a WiFi network.
APN	Access Point Name. Gateway for the cellular data.
BSSID	Basic Service Set Identification. I.e. the MAC address of the WiFi.
GNSS	Global Navigation Satellite System. For example GPS or Galileo.
LTE-M / NB-IoT	Narrowband Cellular Standards for mobile data.
RSSI	Received Signal Strength Indicator. I.e. the strength of the WiFi signal.
SSID	Service Set Identifier. I.e. the name of the WiFi.

Code structure

File/Folder	Content
.github/workflows	Github CI
docs	Documentation
firmware	Firmware running on the device
ntfy_traccar_bridge	Bridge scripts running on the server at a machine in local network
flash_firmware.bash	Flash the firmware to the device

Similar projects

• https://github.com/eaxsi/sim7000-tracker
• https://github.com/onlinegill/LILYGO-TTGO-T-SIM7000G-ESP32-Traccar-GPS-tracker
• https://github.com/Wovyn/lilygo-t-sim7000g-asset-tracker-example