`surveillance-temperature.sh`

BeagleBone Black (TI Sitara AM3358) · File : surveillance-temperature.sh · Language : Bash · Use case : Surveiller la température du processeur et alerter en cas de chauffe

With zero dependencies, this script reads the thermal sensor exposed by the Linux kernel, logs CPU temperature and frequency to CSV and prints an alert past a threshold. Perfect to size passive cooling.

Hardware required

A BeagleBone Black (TI AM3358) on the official Debian image, powered by 5 V mini-USB, with its 3.3 V P8/P9 headers (never put 5 V on the pins!). None: the board measures its own temperature (SoC sensor).

Wiring

No wiring. Check /sys/class/thermal/thermal_zone*/temp exists (otherwise load the SoC thermal module).

How it works

The kernel exposes temperature in milli-°C in sysfs; the script converts it, compares with the threshold and appends a timestamped CSV line. The current frequency confirms thermal throttling. On Debian: sudo apt install gpiod python3-gpiod; the P8/P9 pins are devicetree-named (gpioinfo). Analog inputs AIN0-6 sit on P9 (1.8 V max, via IIO).

Going further

Add forced cooling (pwm-fan in sysfs), or push the CSV to a server with curl in the same cron.

surveillance-temperature.sh

#!/bin/bash
# Surveillance thermique : /sys/class/thermal + journalisation + alerte.
# Aucune dependance : sysfs et bash uniquement.

SEUIL_C="${SEUIL_C:-70}"     # degres avant alerte (variable d'env)
INTERVALLE="${INTERVALLE:-5}" # secondes entre deux mesures
JOURNAL="${JOURNAL:-/tmp/cpu-temp.csv}"

[ -f "$JOURNAL" ] || echo "horodatage,temp_c,frequence_mhz" > "$JOURNAL"

# Premier capteur thermique expose par le noyau (varie selon la carte)
ZONE=$(ls /sys/class/thermal/ | grep ^thermal_zone | head -1)
[ -n "$ZONE" ] || { echo "aucun capteur thermique dans /sys/class/thermal"; exit 1; }
echo "Capteur : $ZONE"

while true; do
  TEMP=$(($(cat /sys/class/thermal/$ZONE/temp) / 1000))  # milli-C -> C
  FREQ=$(awk 'NR==1{print $1/1000}' \
        /sys/devices/system/cpu/cpufreq/policy0/scaling_cur_freq 2>/dev/null || echo 0)
  TS=$(date -Is)
  echo "$TS,$TEMP,$FREQ" >> "$JOURNAL"
  if [ "$TEMP" -ge "$SEUIL_C" ]; then
    echo "$(date +%T) ALERTE : ${TEMP}C >= ${SEUIL_C}C (freq ${FREQ} MHz)"
  else
    echo "$(date +%T) temp ${TEMP}C  freq ${FREQ}MHz"
  fi
  sleep "$INTERVALLE"
done

← Back to the board