LoRA Power Switch Control System ¶

Project Overview ¶

Two-board LoRA system to control a 240V water pump with programmable scheduling and override capabilities.

Hardware Specifications ¶

ESP32 Boards ¶

• 2x LoRa32 V2.1 868MHz ESP32 boards
• All AC powered (no battery requirements)

Switch Board (Remote - Water Pump Location) ¶

Location: 41°52'41.3"N 12°32'25.6"E (street level)
Components:

• ESP32 LoRa32 V2.1
• 40A SSR (240V AC rated for motor loads)
• Snubber circuit (RC: 0.1µF + 100Ω)
• 10A fuse
• IP65 enclosure
• 5V power supply

Home Board (Gateway) ¶

Location: 41°52'45.4"N 12°32'22.9"E (~25-30m height)
Components:

• ESP32 LoRa32 V2.1
• Standard enclosure

Distance: ~150m (well within LoRA range)

System Architecture ¶

WiFi Network → Home Board (Gateway) → LoRA → Switch Board → SSR → Water Pump Circuit
                    ↑
            Web Interface (AsyncWebServer)

Software Architecture ¶

Switch Board Firmware ¶

• LoRA receiver (868MHz)
• Schedule storage (LittleFS)
• Time sync via LoRA commands from home board
• SSR control via GPIO pin
• Failsafe: Circuit CLOSED if communication lost >30s
• Heartbeat transmission every 3s
• Failure Mode: If LoRA fails, pump circuit stays closed (pump available)

Home Board Firmware ¶

• LoRA transceiver (868MHz)
• WiFi client connecting to existing network (DHCP)
• Static IP assigned by router
• NTP client for accurate time
• AsyncWebServer for web interface
• Schedule management and storage
• Command acknowledgment system
• Real-time status display

Communication Protocol ¶

Message Types ¶

• CMD_ON_OVERRIDE - Manual override ON until next schedule
• CMD_OFF_OVERRIDE - Manual override OFF until next schedule
• CMD_ALWAYS_ON - Emergency always ON
• CMD_ALWAYS_OFF - Emergency always OFF
• CMD_SCHEDULE_UPDATE - Update stored schedule
• CMD_TIME_SYNC - Sync time from home board
• STATUS_REQUEST - Request current status
• STATUS_RESPONSE - Current pump state, next event, signal strength
• HEARTBEAT - Every 3s from switch board

Reliable Delivery ¶

• Sequence numbers on all commands
• Acknowledgment packets required
• Automatic retry (3 attempts)
• 30s timeout for communication failure detection

Scheduling System ¶

Default Schedule ¶

• ON: 06:30 (circuit closed - pump available)
• OFF: 22:00 (circuit open - pump disabled)
• DST Aware: Automatic daylight saving time adjustment
• Initial Config: Single daily schedule (no weekday/weekend differentiation)

Features ¶

• Multiple schedule support (future: seasonal adjustments)
• Override until next scheduled event
• Emergency always-on/always-off modes
• Schedule storage in LittleFS on both boards

Web Interface ¶

Requirements ¶

• Responsive design (no mobile app needed)
• No authentication (handled by reverse proxy basic auth)
• Real-time status indicators
• Schedule configuration interface
• Manual override controls
• Emergency controls

Technology Stack ¶

• AsyncWebServer on ESP32
• HTML/CSS/JavaScript served from SPIFFS/LittleFS
• WebSocket for real-time updates
• JSON API for configuration

Physical Implementation ¶

Water Pump Control ¶

• Pump has built-in pressure control
• System only opens/closes electrical circuit
• SSR handles 240V AC switching
• No soft start/stop required

Safety & Protection ¶

• Proper fusing and snubber circuits
• IP65 enclosure for outdoor switch board
• Failsafe defaults to circuit closed (pump available)

Development Plan ¶

Phase 1: Basic Communication ¶

1. Basic LoRA communication between boards
2. Message protocol implementation
3. Reliable delivery with ACK system

Phase 2: Core Functionality ¶

1. Time synchronization (NTP → Home Board → Switch Board)
2. Schedule storage and management
3. SSR control implementation

Phase 3: Web Interface ¶

1. AsyncWebServer setup
2. Schedule configuration UI
3. Real-time status display
4. Manual override controls

Phase 4: Integration & Testing ¶

1. Hardware integration
2. End-to-end testing
3. Failsafe behavior verification
4. Range and reliability testing

Future Enhancements (Docker Services) ¶

• Data logging container
• Schedule backup service
• Historical monitoring dashboard
• REST API gateway for external control

Network Configuration ¶

• Home board connects to existing WiFi
• DHCP with router-assigned static IP
• Standard HTTP port (80) for web interface
• Reverse proxy handles authentication

File Structure ¶

/
├── switch_board/          # Remote switch board firmware
├── home_board/           # Home gateway board firmware
├── web_interface/        # HTML/CSS/JS for web UI
├── docs/                # Documentation
└── PROJECT_SPECS.md     # This file