LoRa Door Control System

Overview

The LoRa Door Control System is a distributed door control solution that leverages LoRa technology for reliable, long-range wireless communication between a central server and multiple door nodes. This system is designed to provide secure access control for buildings, facilities, or any environment requiring controlled door access.

The system utilizes the LoRa (Long Range) protocol, which offers several advantages for this application:

Long-range communication (up to several kilometers in optimal conditions)
Low power consumption, ideal for battery-powered door nodes
Reliable signal penetration through walls and obstacles
Secure communication with built-in encryption

System Architecture

System Architecture Diagram

The system consists of three main components working together to provide reliable door control:

Central Server

TCP server accepting connections from the central LoRa node
Manages door control commands
Implements ping/acknowledgment system
Runs on any Linux/macOS system

Central Node (Raspberry Pi Pico W)

Bridges TCP server with LoRa network
Forwards commands from server to doors
Handles packet routing and acknowledgments
Uses WiFi for server connection
Uses LoRa for door communication

Door Nodes (Raspberry Pi Pico)

Controls physical door mechanisms
Receives and processes LoRa commands
Displays status on OLED screen
Sends acknowledgments back to central node

Protocol

The system uses a custom protocol for reliable communication between components:

Packet Structure

AppID (1 byte): Application identifier
Index (8 bytes): Packet sequence number
Hash (4 bytes): CRC32 validation hash
Command (1 byte): Operation code
Target (1 byte): Target node identifier

Commands

Open (0x01): Open door command
Ping (0x02): Connection check
Ack (0x03): Command acknowledgment

Communication Flow

Server sends command to central node via TCP
Central node forwards command to door node via LoRa
Door node processes command and sends acknowledgment
Central node forwards acknowledgment to server
Server confirms successful command execution

Hardware Requirements

Central Node (Pico W)

Raspberry Pi Pico W
SX127X LoRa module
Connections:
- SPI0: LoRa communication
- GPIO20: LoRa RST
- GPIO17: LoRa CS
- GPIO21: LoRa DIO0
- GPIO22: LoRa DIO1

Door Node (Pico)

Raspberry Pi Pico
SX127X LoRa module
SSD1306 OLED Display (128x64)
Relay module
Connections:
- GPIO15: Relay control
- I2C0: OLED display
- SPI0: LoRa communication
- GPIO20: LoRa RST
- GPIO17: LoRa CS
- GPIO21: LoRa DIO0
- GPIO22: LoRa DIO1

Setup and Configuration

Server Setup

# Build and run the server
go build
./gates

Central Node

# Flash the central node (Pico W)
tinygo flash --target=pico-w -stack-size=8kb central/

Door Node

# Flash the door node (Pico)
tinygo flash --target=pico door/

Configuration Parameters

Edit protocol/config.go to set:

AppID: Application identifier (default: 0x01)
Password: Security password for packet validation
NodeServer: Server node ID (0x00)
NodeDoor: Door node ID (0x01)

LoRa configuration in protocol/config.go:

Frequency: 868.1 MHz
Bandwidth: 125.0 kHz
Spreading Factor: 7
Coding Rate: 4/8
Sync Word: 0x38

Features

Reliable Communication

CRC32 hash validation
Packet sequence tracking
Acknowledgment system
Automatic ping/pong for connection monitoring

Security

Password-based packet validation
Unique node identifiers
Sequence number protection against replay attacks

User Interface

OLED status display on door nodes
Command logging
Connection status monitoring

Development

The project uses TinyGo for embedded development. Required tools:

Go 1.23.4 or later
TinyGo
SSD1306 and SX127X drivers