MeshCore Relay Controller: Switch Relays via LoRa Mesh

This project extends the MeshCore ecosystem with a practical feature: depending on the board and available GPIOs, multiple external relays can be remotely switched via a LoRa node – completely off-grid, without internet or central infrastructure. The number of relays is variable and expandable. The browser-based configurator at relay.meshcore.at is currently in Beta (v2.0).

Browser Flasher with Guided Setup

The configurator uses the Web Serial API and requires Chrome or Edge version 89 or later. Setup follows six steps: board selection, GPIO configuration, security settings, summary, flash process, and verification. Alternatively, users can download generated files (relay_config.h, platformio.ini) and compile with PlatformIO.

GPIO and Switching Logic

The number of relays is configurable. Two switching logic modes are available: Active HIGH (standard for simple modules) and Active LOW (for optocouplers). Serial console commands for testing:

• relay_test 1 – Test pulse
• relay_on 2 – Relay permanently on
• relay_all_off – All off

Remote Control via Mesh Message

Commands in the format PASSWORD:COMMAND are sent to the node. Examples:

• MYPASSWORD:STATUS – Query status
• MYPASSWORD:R3_ON – Relay 3 on
• MYPASSWORD:ALL_OFF – Emergency off

Security

Multi-layered protection includes: relay password, optional node whitelist (authorized nodes only), rate limiting (10 commands/minute, 300-second lockout after 5 failed attempts).

Whitelist management:

• relay_wl_add AABBCCDDEEFF – Add node
• relay_wl_on – Activate whitelist
• relay_wl – Show status

Note for nRF52 Boards

RAK4631 and other nRF52 boards do not support Web Serial flashing. Alternatives: nRF Connect App via Bluetooth DFU or adafruit-nrfutil via USB. DFU mode: double-press the reset button.