signalk-rpi-stats

Comprehensive Raspberry Pi system monitoring for Signal K — CPU, memory, storage, and power/thermal throttling — with no sudo and no native dependencies.

Paths published (default prefix environment.rpi)

• .cpu.temperature (K) — /sys/class/thermal/thermal_zone0/temp
• .cpu.utilisation (ratio, overall) and .cpu.core.<n>.utilisation (per core)
• .cpu.frequency (Hz) — current ARM clock
• .cpu.coreVoltage (V) — vcgencmd measure_volts core
• .cpu.load.1m / .5m / .15m — load averages
• .memory.utilisation (ratio), .memory.total, .memory.used, .memory.available (bytes)
• .storage.utilisation (ratio), .storage.capacity, .storage.used, .storage.available (bytes) — for the configured mount (default /)
• .uptime (s)
• .throttling.underVoltage / .throttled / .freqCapped / .softTempLimit (bool, current)
• .throttling.underVoltageOccurred / .throttledOccurred (bool, sticky since boot)
• notifications.<prefix>.throttling — alarm on active under-voltage / throttling

How it reads (no sudo, no native modules)

• CPU utilisation is computed from os.cpus() deltas between samples — no sysstat needed.
• Temperature, frequency, memory and storage come from /sys, /proc, and statfs.
• Core voltage and throttling come from vcgencmd (a PATH binary on Raspberry Pi OS).

Requirements

• Raspberry Pi (tested on Pi 5 / Bookworm).
• For core voltage + throttling flags only: the Signal K user must be in the video group and vcgencmd must be present (both default on Raspberry Pi OS). Everything else works with no extra packages.

Install

From the Signal K appstore, or with npm:

cd ~/.signalk
npm install signalk-rpi-stats

Then enable Raspberry Pi Stats in the Signal K plugin config and restart the server.

Configuration

| Option | Default | Notes | |---|---|---| | Sample rate (s) | 10 | | | Base Signal K path | environment.rpi | prefix for all paths | | Per-core CPU utilisation | true | also publish .cpu.core.<n>.utilisation | | Storage filesystem | / | mount to report storage for | | Report throttling | true | uses vcgencmd get_throttled | | Notify on under-voltage/throttling | true | raise an alarm notification |

Notes

• On the Pi 5 there is a single SoC thermal sensor, so "CPU temperature" is the SoC temperature.
• The throttling flags use the official vcgencmd get_throttled bitmask; *Occurred flags are sticky since boot. The notification firing on under-voltage is a good early warning for marine 12 V power-supply issues.

Credits / license

In the lineage of signalk-raspberry-pi-temperature / -monitoring / rpi-monitor, rebuilt dependency-free and sudo-free for the Pi 5. Licensed under Apache-2.0.