Rasperry PI-based GPS Tracker

Overview

This system is a Python-based GPS tracking and BLE scanning solution designed to run on Raspberry Pi OS (Lite) with a Qualcomm SIM7000E GSM/GPS module. The system provides real-time location tracking, BLE device scanning, and network connectivity over both GSM and WiFi interfaces.

Architecture

Core Components

1. Main Controller (supervisor.py)

   • Manages all system threads and components
   • Handles error states and recovery
   • Coordinates tasks timing and execution

2. Modem Management (modemdler.py)

   • Controls the SIM7000E GSM/GPS modem
   • Handles hardware power management
   • Provides communication layer initialization

3. Network Management (networker.py)

   • Monitors network connectivity (GSM and WiFi)
   • Manages connection states and transitions
   • Implements UDP packet transmission
   • Handles bearer network activation/deactivation

4. BLE Scanner (blendler.py)

   • Scans for BLE devices
   • Filters and tracks device presence
   • Maintains device histories and visibility states

5. Data Packaging (packager.py)

   • Coordinates GPS data acquisition
   • Builds data packets with GPS, BLE, and system info
   • Manages packet queuing and transmission

6. AT Command Interface (commander.py)

   • Provides AT command functions for the modem
   • Implements cellular, HTTP, and GPS functions
   • Handles PDP context and bearer management

7. Serial Communication (serialer.py)

   • Manages serial port communication with the modem
   • Handles timeout detection and recovery
   • Processes AT command responses

8. Firmware & Config Updates (updater.py)

   • Manages remote firmware updates
   • Downloads and applies configuration changes
   • Handles WiFi network configuration

9. Support Utilities (support.py)

   • Provides logging functionality
   • Implements system shell command execution
   • Handles time synchronization and formatting utilities

Key Features

• Dual Network Connectivity: Seamless switching between GSM and WiFi networks
• GPS Tracking: Real-time GPS location tracking with adjustable intervals
• BLE Device Scanning: Detection and tracking of nearby BLE devices
• Remote Management: OTA firmware updates and remote configuration
• Adaptive Reporting: Dynamic reporting frequency based on movement detection
• Encrypted Communications: Data encryption using Salsa20 cipher
• Resilient Operation: Automatic recovery from errors and connection failures
• Power Management: Optimized power usage based on movement state

Technical Specifications

Hardware Requirements

• Raspberry Pi 0w or compatible
• Qualcomm SIM7000E GSM/GPS modem
• UART interface connection between Pi and modem

Communication

• Uplink: UDP packets containing GPS coordinates, BLE device info, and system status
• Downlink: HTTP GET requests for configuration and firmware updates
• Local: UART communication with modem via AT commands

System Behavior

• Movement Detection: Adapts reporting frequency based on detected movement
• Connection Management: Prioritizes WiFi over GSM when available
• Error Recovery: Implements multi-level error recovery strategies
• Data Persistence: Maintains operation through connectivity outages with packet queuing

Configuration

• Remote Configuration: Updates APN, PIN, and WiFi settings from server
• Firmware Updates: OTA firmware updates with version tracking and rollback capability
• Time Synchronization: GPS-based time synchronization

Error Handling Codes

The system implements a hierarchical error handling system:

• W0, W1: System-level errors requiring reboot or process restart
• M0-M3: Modem-related errors requiring various recovery actions
• N0-N2: Network-related errors or state changes
• U0-U2: Update-related errors or actions