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Adding Nodes

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Rojo edited this page Jul 30, 2026 · 1 revision

Adding More Nodes

soundspy is designed to scale horizontally with no per-node configuration. The firmware is generic — the same binary runs on every board. Node identity is derived at runtime from the ESP32's chip ID, so you never need to rebuild or modify anything for a new node.

Steps

  1. Wire the new ESP32 + mic using the same hardware wiring.

  2. Flash the existing firmware binary via USB:

    arduino-cli upload -p /dev/ttyUSB0 --fqbn esp32:esp32:esp32 \
  --input-file builds/soundspy_latest.bin

    If you have not built firmware yet, run ./scripts/build_firmware.sh first.

  3. Power on the new node. It will connect to WiFi and MQTT, derive its chip ID, and begin publishing to soundspy/<chip_id>/data.

  4. The dashboard auto-discovers the new node and assigns it a name (node-2, node-3, etc.). Click the name to rename it.

No Rebuild Needed

The same builds/soundspy_latest.bin can be flashed to any number of boards. WiFi credentials and MQTT addresses are baked in at build time from .env. If your network config has not changed since the last build, there is nothing to regenerate.

If you need to update credentials or addresses, rebuild once:

./scripts/build_firmware.sh

Then flash the new binary to all nodes — either via USB for the first flash, or via OTA for nodes already running:

./scripts/deploy_ota.sh <chip_id>

Subsequent OTA Updates

Once a node has been flashed once via USB, all future updates can be done wirelessly from the dashboard UI or the CLI:

./scripts/deploy_ota.sh <chip_id>

The chip_id is visible in the dashboard node card and in the serial output during boot.

Resource Considerations

Each node adds one MQTT subscriber connection, one WebSocket audio stream, and one 3600-sample in-memory history deque in the dashboard. The dashboard is single-threaded (Flask-SocketIO with eventlet), so at very high node counts (10+) you may want to profile memory and SocketIO broadcast latency. For typical home or small-studio use, a dozen nodes on a modest server is well within range.

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