🛠 Vérifier l'identité et la santé d'un CM3+ avec vcgencmd

Objectives

Before starting any project with a Compute Module 3+, you need to identify the board, verify that the firmware is recent enough, and check the power supply and temperature. Two documented pitfalls: the CM3+ requires an image/firmware dated November 2018 or later to function (datasheet RP-008163-DS §1) — an old CM3 SD card will refuse to boot; and thermal throttling kicks in at 80 °C on this module. The SoC is a Broadcom BCM2837B0 quad Cortex-A53 limited to 1.2 GHz, with 1 GB of LPDDR2.

Hardware

• CM3+ module (8/16/32/64 GB eMMC) or CM3+ Lite on a CMIO3 or equivalent carrier board
• HDMI display, USB keyboard, 5 V / 2.5 A minimum power supply (VBAT requires up to 3.5 W)
• Recent 32-bit Raspberry Pi OS image (Pi 3B+ images are suitable), flashed after November 2018

Full Code

# Identité matérielle
cat /proc/cpuinfo | grep -E 'Hardware|Revision' vcgencmd versionmap # date du firmware

# Santé électrique et thermique
sudo vcgencmd get_throttled   # 0x0 = rien anormal
vcgencmd measure_temp         # température du die (°C)
vcgencmd measure_volts core
vcgencmd get_mem arm && vcgencmd get_mem gpu

# Fréquence CPU réelle (doit plafonner à 1 200 000 000 Hz)
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

Expected Verification

vcgencmd versionmap displays a firmware date later than November 2018; get_throttled returns 0x0 at idle; measure_temp stays below 60 °C at idle; the CPU frequency rises up to 1.2 GHz. The board type (Revision) corresponds to a BCM2837B0 of the Pi 3B+ class.

Common Errors

• Reusing an SD card or eMMC from an old CM3: if the firmware dates from before November 2018, the CM3+ will not boot at all — this is the #1 pitfall listed in datasheet §1, you must re-flash a recent image.
• Interpreting throttled=0x10000 as a failure: bit 12 simply indicates a past undervoltage — check the cable and the 5 V power supply.
• Expecting 1.4 GHz like on a Pi 3B+: the module is intentionally capped at 1.2 GHz by its power supply (datasheet §10).
• Looking for Wi-Fi or Ethernet on the module: the CM3+ has neither radio nor Ethernet controller, everything goes through the carrier board (single USB 2.0 bus).
• Confusing the die temperature (throttling limit 80 °C) with the maximum ambient temperature of the component (up to +80 °C in a ventilated case according to the datasheet).