Tag Archives: raspberry pi

Raspberry Pi sensors – Munin graphing plugin

I love Munin!  I’ve finally got one of the Raspberry Pi’s to be reasonably stable, so I’ve set up a munin-node on it.  The standard Linux sensord stuff doesn’t run on the arm core, so I had assumed I wouldn’t be able to see any exciting temperature graphs, but I was wrong!

The Raspberry Pi Debian image includes a command called vcgencmd, which allows root to interrogate various settings and measurements.  That includes the temperature, clock frequencies and voltages across various components.

So I’ve knocked up a quick plugin for Munin which gathers that stuff and graphs it.  You can get it over at GitHub here.  The current code looks like this (but the GitHub copy will be most up-to-date),

#!/bin/bash
# -*- sh -*-

: << =cut

=head1 NAME

pisense_ - Wildcard-plugin to monitor Raspberry Pi sensors (temp, volts, clock speed)

=head1 CONFIGURATION

This plugin needs to be run as root for vcgencmd to work.

[pisense_*]
user root

=head2 ENVIRONMENT VARIABLES

This plugin does not use environment variables.

=head2 WILDCARD PLUGIN

This is a wildcard plugin. To specify if you want temperature,
clock speed or volts, link this file to _volt, _temp
or _clock.

For example,

ln -s /usr/share/munin/plugins/pisense_ \
/etc/munin/plugins/pisense_clock

will monitor the clock speeds of your pi.

=head1 BUGS

None known.

=head1 NOTES

This plugin is shamelessley based on the ip_ plugin (structure).

=head1 MAGIC MARKERS

#%# family=auto
#%# capabilities=autoconf suggest

=head1 AUTHOR

Tony (tony@darkstorm.co.uk).

=head1 LICENSE

It's yours, do with it what you like.

=cut

. $MUNIN_LIBDIR/plugins/plugin.sh

sensor=${0##*/pisense_}

if [[ "$1" == "autoconf" ]]; then
    if ! /opt/vc/bin/vcgencmd firmware >/dev/null 2>/dev/null; then
        echo "no (could not run /opt/vc/bin/vcgencmd as user $(whoami))"
        exit 0
    else
        echo yes
        exit 0
    fi
fi

# this is flawed, vcgencmd always returns with RC 0. Needs expanding.
if [[ "$1" == "suggest" ]]; then
    if /opt/vc/bin/vcgencmd measure_temp >/dev/null 2>/dev/null; then
        echo temp
    fi
    if /opt/vc/bin/vcgencmd measure_volts >/dev/null 2>/dev/null; then
        echo volt
    fi
    if /opt/vc/bin/vcgencmd measure_clock core >/dev/null 2>/dev/null; then
        echo clock
    fi
    exit 0
fi

if [[ "$1" == "config" ]]; then

    if [[ "$sensor" == "temp" ]]
    then
        echo "graph_title Raspberry Pi core temp"
        echo "graph_args --base 1000"
        echo "graph_vlabel dgrees Celsius"
        echo "graph_category sensors"
        echo "temp.label Core Temperature"
        echo "temp.min 0"
    fi
    if [[ "$sensor" == "clock" ]]
    then
        echo "graph_title Raspberry Pi clock frequencies"
        echo "graph_args --base 1000"
        echo "graph_vlabel herz"
        echo "graph_category sensors"
        for clock in arm core h264 isp v3d uart pwm emmc pixel vec hdmi dpi
        do
           echo "clock$clock.label $clock clock Frequency"
           echo "clock$clock.min 0"
           echo "clock$clock.type GAUGE"
        done
    fi
    if [[ "$sensor" == "volt" ]]
    then
        echo "graph_title Raspberry Pi voltages"
        echo "graph_args --base 1000"
        echo "graph_vlabel volts"
        echo "graph_category sensors"
        for volt in core sdram_c sdram_i sdram_p
        do
           echo "volt$volt.label $volt voltage"
           echo "volt$volt.min 0"
           echo "volt$volt.type GAUGE"
        done
    fi

    exit 0
fi;

if [[ "$sensor" == "temp" ]]
then
    temp=$(/opt/vc/bin/vcgencmd measure_temp | awk -F"=" '{print $2}' | awk -F"'" '{print $1}')
    echo "temp.value $temp"
fi
if [[ "$sensor" == "clock" ]]
then
    for clock in arm core h264 isp v3d uart pwm emmc pixel vec hdmi dpi
    do
       clockval=$(/opt/vc/bin/vcgencmd measure_clock $clock | awk -F"=" '{print $2}')
       echo "clock$clock.value $clockval"
    done
fi
if [[ "$sensor" == "volt" ]]
then
   for volt in core sdram_c sdram_i sdram_p
   do
       voltage=$(/opt/vc/bin/vcgencmd measure_volts $volt | awk -F"=" '{print $2}' | tr -d "V")
       echo "volt$volt.value $voltage"
   done
fi

I’ll post some sample screenshots in a bit!

Problems with my Pi

I have a couple of Raspberry Pi’s (long story as to why I have two).  I spent a few hours one day a couple of weeks ago setting one of them up – pretty impressive, but I felt the overall performance was disappointing.  I moved the Pi between rooms in the house, did some more setup and then left it running for a few days.

Everything seemed okay.  Then one morning, it wasn’t responding.  I was running it headless and I could no longer SSH into it.  I had no choice but to power it off because it was no where near a composite or HDMI device.  Once powered off, it wouldn’t boot again at power on.  I carried it back through into the room with a TV, powered it up, and discovered the filesystem was corrupt.

No problem, pull out the SDHC card, whack it into a USB adapter, plug it into another Linux machine and fsck it.  That had a billion errors, I was impressed at quite how badly it had been corrupted.  I didn’t really think much more about it, I had a second SDHC card with raspbian already on it, and I didn’t really do much with the machines for a few weeks.

The day before yesterday, the Linux box I use to backup the other machines developed a fault, so I thought it would be the perfect time to replace it with one of the Pi’s.  Got it all set up on the shelf, hidden away, and ran it for a day.  Terrible disk IO performance, but otherwise okay.  I read around a bit and discovered that the SDHC card performance can be quite bad.  So I put a USB thumb drive in (16GB) with the intention of moving everything except /boot onto that to improve performance.

Except, when I reboot it – it wouldn’t boot.  Sure enough, corrupt filesystem.  I went back to check the original SDHC card and discovered not only was the filesystem corrupt, the card is damaged.  The second card doesn’t appear to be damaged but it would seem any power fluctuation in the Pi, or any power off without a shutdown, can trash the filesystem beyond recovery.

Now I’m concerned the Pi’s aren’t reliable enough to have sitting in the corner running 24×7.  A browse on the web shows I’m not alone either.  Quite disappointing.