fsp2mqtt

Bridge from an FSP "Twin" redundant PSU (e.g. FSP930-20REB) to MQTT, using the Home Assistant discovery format. OpenHAB consumes the same topics.

The PSU exposes PMBus telemetry over a Silicon Labs CP2112 HID-to-I2C bridge. The Linux hid_cp2112 driver presents it as a regular I2C adapter (/dev/i2c-N), so the bridge just talks SMBus to the two PSU modules:

Address	Module
0x58	PSU 1
0x59	PSU 2

Per module it reads VIN, VOUT, IOUT, TEMP1/TEMP2, FAN, POUT, PIN and STATUS_WORD (decoded from PMBus LINEAR11/LINEAR16), plus an aggregate output power and a redundancy-degraded indicator.

Published topics

• HA discovery configs under homeassistant/{sensor,binary_sensor}/<device_id>/.../config (retained)
• State under fsp/<device_id>/psuN/<metric> and fsp/<device_id>/total_pout (retained)
• Availability / LWT on fsp/<device_id>/availability (online/offline)

Networking

The container only needs to reach the MQTT broker. In docker-compose.yml it joins an internal bridge network shared with the broker and resolves it by name (MQTT_HOST=mqtt), so it needs no LAN IP. Adjust MQTT_HOST / the network to match your setup (a plain bridge that can reach your broker also works).

Requirements

• The CP2112 USB device available on the host running the container (e.g. passed through to a VM). The hid_cp2112 kernel driver exposes it as an I2C adapter (/dev/i2c-N).
• The /dev/i2c-N node mapped into the container (see docker-compose.yml). I2C_BUS=auto finds the CP2112 adapter by name; if the bus index changes, update the devices: mapping accordingly.

Setup

1. Copy .env.example to .env and set your MQTT broker host/credentials.
2. docker compose up -d --build

Debug

docker logs -f fsp2mqtt
mosquitto_sub -h <broker> -u <user> -P '<pwd>' -t 'fsp/#' -v

License

MIT — see LICENSE.