Raspberry Pi CPU Usage Monitoring With A BerryClip

While wandering the internet I found an article Raspberry Pi: CPU usage monitoring using GPIO by chteuchteu. This explained how to display the current CPU usage on 7 LEDs attached to the GPIO header.

I thought this would be a great application to convert for use with a BerryClip 6 LED Buzzer board. So I modified the original code to use 6 LEDs and tweaked a few of the functions. Apart from the LED count I changed the script to use an array of GPIO references so it would be easier to update if you used different pins.

I started with a fresh install of the latest Raspbian SD card image.

#!/bin/bash
#--------------------------------------
#    ___                   ________
#   / _ )___ __________ __/ ___/ (_)__
#  / _  / -_) __/ __/ // / /__/ / / _ \
# /____/\__/_/ /_/  \_, /\___/_/_/ .__/
#                  /___/        /_/
#
#       BerryClip - 6 LED Board
#
# This script uses 6 LEDs to display the
# current CPU usage.
#
# Author : Matt Hawkins
# Date   : 12/05/2013
#
# https://www.raspberrypi-spy.co.uk/
#
# Original script created by chteuchteu
# http://www.chteuchteu.com/
#
# Modified by Matt Hawkins to use the 6 LEDs
# on the BerryClip addon board.
#
# BerryClip LED reference :
# LED 1  - Pin 7  - GPIO4
# LED 2  - Pin 11 - GPIO17
# LED 3  - Pin 15 - GPIO22
# LED 4  - Pin 19 - GPIO10
# LED 5  - Pin 21 - GPIO9
# LED 6  - Pin 23 - GPIO11
#
#--------------------------------------

# Create array of GPIO references
led[1]="11"
led[2]="9"
led[3]="10"
led[4]="22"
led[5]="17"
led[6]="4"

# Configure GPIOs to be outputs
echo ${led[1]} > /sys/class/gpio/export 2> /dev/null
echo ${led[2]} > /sys/class/gpio/export 2> /dev/null
echo ${led[3]} > /sys/class/gpio/export 2> /dev/null
echo ${led[4]} > /sys/class/gpio/export 2> /dev/null
echo ${led[5]} > /sys/class/gpio/export 2> /dev/null
echo ${led[6]} > /sys/class/gpio/export 2> /dev/null
echo "out" > /sys/class/gpio/gpio${led[1]}/direction
echo "out" > /sys/class/gpio/gpio${led[2]}/direction
echo "out" > /sys/class/gpio/gpio${led[3]}/direction
echo "out" > /sys/class/gpio/gpio${led[4]}/direction
echo "out" > /sys/class/gpio/gpio${led[5]}/direction
echo "out" > /sys/class/gpio/gpio${led[6]}/direction

#################################################
#                   FUNCTIONS                   #
#################################################

number=0
gpio=0

function LEDON {
  # Turn ON the LED "number"

  gpio=${led[number]}

  echo "1" > /sys/class/gpio/gpio$gpio/value
  number=0
  gpio=0
}
function LEDOFF {
  # Allow you to turn off the del (the number of the del is contained in "number")
  # number  pin is done at the begining of the function

  gpio=${led[number]}

  echo "0" > /sys/class/gpio/gpio$gpio/value
  number=0
  gpio=0
}

function allON
{
  # Turn ON all the LEDs
  for i in {1..6}
  do
     number=i ; LEDON
  done

}
function allOFF
{
  # Turn OFF all the LEDs
  for i in {1..6}
  do
     number=i ; LEDOFF
  done

}
function flash
{
  counter=0
  while [ $counter -le $1 ]
  do
    allON ; sleep 0.2
    allOFF ; sleep 0.2
    counter=$(( $counter + 1 ))
  done

}

#################################################
#                   MAIN CODE                   #
#################################################

# Turn ON all LEDs in sequence
number=1 ; LEDON ; sleep 0.2
number=2 ; LEDON ; sleep 0.2
number=3 ; LEDON ; sleep 0.2
number=4 ; LEDON ; sleep 0.2
number=5 ; LEDON ; sleep 0.2
number=6 ; LEDON ; sleep 1

# Turn all LEDs OFF
allOFF

# Flash the LEDs 5 times
flash 5

# Start main loop
while true ; do

  # Obtain the current CPU usage percentage
  idle=`vmstat 2 3 | tail -n1 | sed "s/\ \ */\ /g" | cut -d' ' -f 16`
  cpu=$(( 100 - idle ))

  # Switch the LEDs ON or OFF the "cpu" value
  allOFF
  if [ ${cpu} -lt 5 ] ; then
    allOFF
  elif [ ${cpu} -lt 23 ] ; then
    number=1   ; LEDON
  elif [ ${cpu} -lt 41 ] ; then
    number=1   ; LEDON
    number=2   ; LEDON
  elif [ ${cpu} -lt 59 ] ; then
    number=1   ; LEDON
    number=2   ; LEDON
    number=3   ; LEDON
  elif [ ${cpu} -lt 77 ] ; then
    number=1   ; LEDON
    number=2   ; LEDON
    number=3   ; LEDON
    number=4   ; LEDON
  elif [ ${cpu} -lt 95 ] ; then
    number=1   ; LEDON
    number=2   ; LEDON
    number=3   ; LEDON
    number=4   ; LEDON
    number=5   ; LEDON
  else
    number=1   ; LEDON
    number=2   ; LEDON
    number=3   ; LEDON
    number=4   ; LEDON
    number=5   ; LEDON
    number=6   ; LEDON
  fi

done

# Turn all LEDs OFF
allOFF

exit 0

This script can be downloaded directly to your Pi using the following command :

wget https://www.raspberrypi-spy.co.uk/berryclip/6_led/berryclip_cpu_01.sh

The script must be made executable :

chmod +x berryclip_cpu_01.sh

It can then be run from the command line using :

sudo ./berryclip_cpu_01.sh &

The ampersand on the end of the line is required to run the script as a background process and give you your command line back. The number displayed when you run the script is the process ID. You can check the process is still running by typing :

ps aux | grep berryclip

You should see a process with the same ID. If you want to close the process you can type :

sudo kill 1234

Where 1234 is your process ID.

The LEDs will light up based on the CPU utilisation. The percentages required to light each LED are shown below :

None   less than 5%
1 LED  5% or greater
2 LED 23% or greater
3 LED 41% or greater
4 LED 59% or greater
5 LED 77% or greater
6 LED 95% or greater

If you now run “startx” and use some applications (Midori for example) you will see the CPU monitor spring into life! If you don’t like the percentages used in this example they are easy enough to change by adjusting the appropriate numbers in the script.

Here are some photos of the monitor in action :