iMX8M Industrial Environmental chamber testing

On this page environmental stress testing results of iMX8M Industrial Development Kit are displayed. Detailed instructions how to setup boards are also shown.

Hardware configuration

All of the modules used standard specification except of the temperature ranges for the key components as described below:

• 3x iMX6 TinyRex Development Kit in Max configuration
  • i.MX6 Quad 1.0 GHz CPU - automotive temperature range (-40°C to +125°C)
  • 2GB DDR3 Memory (4x 4Gb DDR3 Memory chips) - industrial temperature range (-40°C to +95°C)
  • 1GBps Ethernet PHY Tranciever KSZ9031RN - automotive temperature range (-40°C to +85°C)

• 3x iMX6 TinyRex Development Kit in Pro configuration
  • i.MX6 Dual 1.0 GHz CPU - automotive temperature range (-40°C to +125°C)
  • 1GB DDR3 Memory (4x 2Gb DDR3 Memory chips) - industrial temperature range (-40°C to +95°C)
  • 1GBps Ethernet PHY Tranciever KSZ9031RN - automotive temperature range (-40°C to +85°C)

• 3x iMX6 TinyRex Development Kit in Basic configuration
  • i.MX6 Solo 1.0 GHz CPU - extended temperature range (-20°C to +105°C)
  • 512MB DDR3 Memory (2x 2Gb DDR3 Memory chips) - industrial temperature range (-40°C to +95°C)
  • 1GBps Ethernet PHY Tranciever KSZ9031RN - automotive temperature range (-40°C to +85°C)

All of the tested development kits used standard configuration of iMX6 TinyRex Base Board with extended temperature range (-20°C to +85°C). The majority of tested kits used a standard heatsink. This heatsink sized 35x35x10mm is included in every development kit package. Thus these measurements show the actual performance of web shop based configuration. Some of the boards were mounted into a custom build iMX6 TinyRex aluminium case.

The setup in the environmental chamber:

Test description

Three iMX6 TinyRex Development Kits (one in Max, one in Pro and one in Basic version) were running full peripheral test and stressed all the peripherals in different range of temperatures. All the rest of the boards were running CPU and memory tests to check the reliability and stability of the firmware and hardware design.

Configuration, software and testing threads in details:

3x iMX6 TinyRex peripheral stress testing

• 1 thread of extensive Memory stress test
• 1 thread of CPU stress test
• SATA stress test (applied for Max and Pro versions only)
• receiving and processing HDMI Input signal through video input circuitry
• sending this video stream over HDMI Output to external monitor
• copying a file from the first USB drive to SD card and vice versa
• copying a file from the second USB device to SATA hard drive and vice versa (applied for Max and Pro versions)
• copying a file from the second USB drive to SD card and vice versa (applied for Basic version)
• pinging the host PC via Ethernet
• all the messages were printed out on the serial console through connected FTDI cable
• firmware running from SD card
• standard 35x35x10mm heatsink

2x iMX6 TinyRex Max Memory stress testing

• 4 threads of extensive Memory stress test
• 4 threads of CPU stress test
• reading CPU temperature via SSH Ethernet session
• serial FTDI cable used for displaying messages
• firmware running from SD card
• one set mounted inside the aluminium case

2x iMX6 TinyRex Pro Memory stress testing

• 2 threads of extensive Memory stress test
• 2 threads of CPU stress test
• reading CPU temperature via SSH Ethernet session
• serial FTDI cable used for displaying messages
• firmware running from SD card
• one set mounted inside the aluminium case

2x iMX6 TinyRex Basic Memory stress testing

• 1 threads of extensive Memory stress test
• 1 threads of CPU stress test
• reading CPU temperature via SSH Ethernet session
• serial FTDI cable used for displaying messages
• firmware running from SD card
• one set mounted inside the aluminium case

USB flash devices and SATA hard drives were placed outside the environmental chamber. All the scripts running during the test and the board setup instructions can be found in section How to prepare the test.

Testing Results

The picture below shows the temperature profile during the whole testing process:

Running the boards at -40°C – PASS

Test description: CPU, Memory and peripheral stress tests were running at -40°C. All the tested kits were working without errors during the whole time, even if some components used for iMX6 TinyRex Module Basic were only rated for temperature range between -20°C and +105°C. iMX6 TinyRex Base Boards were running at this temperature with components certified only from -20°C to +85°C temperature range.

A closer image on the temperature chamber displaying the minimum temperature is shown below. These readouts are available on the display:

• the first number shows relative humidity
• the second one current temperature
• the last one the dew point

Running the kits at high temperatures (from +60°C to +100°C) – PASS

Test description: The ambient temperature was gradually increasing (from 60°C up to 100°C) while CPU, Memory and peripheral stress tests were running. The moment when CPU frequency had decreased was used as a test threshold (this occurred when CPU temperature reached +70°C up to +100°C). Components used for iMX6 TinyRex Base Boards were only rated from -20°C to +85°C operating temperature range.

Temperature stress test – quick change from -40°C to -10°C and back – PASS

Test description: The ambient temperature was quickly increased from -40°C to -10°C and then back to -40°C. The boards were running CPU, Memory and peripheral stress tests. All the boards were working correctly.

Temperature stress test – quick change from +90°C to +30°C and back – PASS

Test description: The ambient temperature was quickly decreased from +90°C to +30°C and back to +90°C while running CPU, Memory and peripheral stress tests. All boards were working without errors.

Thermal camera focused on the boards as the set temperature inside the chamber reached +85°C:

Switch ON/OFF test – PASS

Test description: At temperatures from -30°C to -40°C the boards were switched OFF, left OFF for at least 5 minutes (to cool down completely) and then switched ON to see if they boot up without problems. Once booted up into Linux, the boards were turned off again. All of the tested boards booted up successfully. This test was performed 3 times at -30°C, -35°C and -40°C temperatures.

Cooling performance at high temperatures

Test description: As mentioned above, different heatsinks and enclosures were utilized in order to compare the cooling abilities. All these tests were performed with Max version which generate the most heat by itself. All setup reached temperature +85°C in the chamber while still successfully running. The board in the enclosure with the biggest height and cooling fins on the top size reached +100°C.

PC setup

During the test DHCP and FTP servers were utilised. The PC was also used during Ethernet ping test while controlling all the boards through SSH and serial console sessions. The control computer was running Windows 7 operating system.

Setting the network

Disable firewall (PC will not be connected to the Internet) and setup a static IP address: Press Windows button -> go to Control Panel -> Network and Internet -> Network and Sharing Center -> Change adapter settings (on the right side in the bar) -> double click on Local Area Connection -> Properties -> In the tab Networking go to Internet Protocol Version 4 (TCP/IPv4) -> type the static IP address and subnet mask as shown below:

Enabling sharing

iMX6 TinyRex Development kits and the control PC are connected via Gigabit Ethernet switch. To ensure correct IP address assignment, turn on the PC first, connect it with the switch and only after that turn the switch on. To be able to download the files from the FTP server, sharing option need to be enabled first. This can be done by setting up the network as a work network. Sharing can be enabled in Control Panel -> Network and Internet -> Network and Sharing Center -> Click to Choose homegroup and sharing options:

Setting up the TFTP and DHCP servers

Tftpd32 software supports both TFTP and DHCP server options. For more details about DHCP configuration, follow the screenshots below:

SSH and Serial consoles

To control iMX6 TinyRex Development Kits, one TeraTerm serial console was opened per board. SSH clients were used to read temperature. For the boards with the peripheral test, an extra SSH client was established to be able to spot possible errors or warnings if occurred.


The setup of the environmental chamber cables and out-of-chamber equipment:

Preparing the test

Boot device and software

SD card was selected as a booting device for all the boards. U-Boot settings were not adjusted as the default configuration was used. The only change compared to standard software package was running a multimedia filesystem. To prepare a fresh SD card follow these instructions. Here is an example of creating a SD card suitable for Max configuration:

git clone https://github.com/voipac/imx6tinyrex_bin_linux
cd imx6tinyrex_bin_linux/
sudo ./fsl-sdcard-partition.sh -max /dev/mmcblk0

Downloading stress test

Stressapptest package was selected to check CPU and memory integrity. Placing this file into the same directory where the testing script will be stored is important:

wget http://downloads.voipac.com/files/iMX6_TinyRex_Development_Kit/module/documents/Environmental_chamber_testing/stressapptest

Setup the cron

To be able to check the CPU temperature every minute a new cron job was setup. For Ubuntu file systems postfix package installation is required:

sudo apt-get install postfix

To setup a cron tab, the file containing all cron jobs needs to be altered. Before running the crontab for the first time, selecting a text editor is required:

sudo crontab -e

Paste the following line to the end of the cron list file. The output time format will be set the same as for stressapptest. Cron job performs a current CPU temperature readout and the data are saved in the log file. The log format was selected identical to the one used by stressapptest package:

* * * * * { echo -n $(date +%Y/%m/%d-%T); echo -n "("; echo -n $(date +%Z); echo -n ") "; cat /sys/devices/virtual/thermal/thermal_zone0/temp; } >> ~/testing-env-chamber/cpu-temp.log

Note: The percent sign '%' has a special purpose in the cron file. As this sign is needed to write the date formats, the backslash is required to be placed before the percent sign: '\%'.

Setting up the date

If the master PC is equipped with a timeserver, server date and time can be automatically obtained using this Linux feature:

ntpdate 192.168.0.2

Time and date can also be set up manually (use format MMDDhhmmYYYY e.g. 07th of July 2016 4:27 pm):

date 071116272016

Setup the CPU temperature printout

Open one SSH client per board where CPU temperature will be shown. Tail command is utilized to display the last part of the log file, which is filled up as the CRON job outputs the current readouts:

tail -F cpu-temp-measuring.log

Error checking during peripheral test

To make sure tests are running smoothly, potential errors can be detected by opening another SSH session:

tail -f env-chamber-testing.log | grep -i "error"

Play video file for peripheral test

To be able to test HDMI Input during the peripheral testing, a video file was played from boards which were running memory stress tests only. Infinite loop is opened in another SSH session:

while [ true ]; do gst-play-1.0 /media/ploughing.mp4; done

Start CPU and memory stress test

Navigate into the directory, where stressapptest feature and test are stored.

Stress command for Max configuration:

./stressapptest -s 600000 -M 1000 -m 4 -C 4 -W -l ~/env-chamber-testing/stressapptest.log --printsec 100

Stress command for Pro configuration:

./stressapptest -s 600000 -M 700 -m 2 -C 2 -W -l ~/env-chamber-testing/stressapptest.log --printsec 100

Stress command for Basic configuration:

./stressapptest -s 600000 -M 150 -m 1 -C 1 -W -l ~/env-chamber-testing/stressapptest.log --printsec 100

Start peripheral test

Before the test start it is a good practice to make sure that all the devices were plugged in successfully. To find out where the devices were mounted following command can be used:

fdisk -l

The testing script uses multiple variables to specify its operation. As the first parameter board configuration is used (-max, -pro or -basic). As other parameters device names are written in the following order: the first USB stick, the second USB, SD card and SATA drive (if used). All logs are stored into a single file.

Starting peripheral test for Max configuration:

./imx6-tinyrex-v1i1-peripheral-test.sh -max sdb1 sdc1 mmcblk2p2 sda2 2>&1 | tee -i trx-env-chamber-testing.log

Starting peripheral test for Pro configuration:

./imx6-tinyrex-v1i1-peripheral-test.sh -pro sdb1 sdc1 mmcblk2p2 sda1 2>&1 | tee -i trx-env-chamber-testing.log

Starting peripheral test for Basic configuration:

./imx6-tinyrex-v1i1-peripheral-test.sh -basic sda1 sdb1 mmcblk2p2 2>&1 | tee -i trx-env-chamber-testing.log

The complete script can be found in the download section or down below:

#!/bin/sh
 
# iMX8MQ environmental chamber peripheral test
  
mountDevice() {
  mkdir -p "/media/$2"
  mount /dev/$1 /media/$2
  cat /proc/mounts | grep -F "/dev/$1 /media/$2"
  if [ "$?" -eq "0" ]; then
    echo "$2 mounted"
  else
    echo "$2 not mounted"; exit 2
  fi
}
 
# prepare files
cd ~/
mkdir -p env-chamber-testing/
cd env-chamber-testing/
   
touch env-chamber-testing.log
touch cpu-temp.log
 
basic=0
pro=0
max=0
case $1 in
  -basic)  basic=1 ;;
  -pro)  pro=1 ;;
  -max)  max=1 ;;
  *)
esac
  
# mount devices
mountDevice $2 usb0
mountDevice $3 usb1
mountDevice $4 mmc0
 
updateLogFiles() {
  # obtain board ID from IP address - be sure addresses are allocated based on MAC
  boardID=$(/sbin/ip -o -4 addr list eth0 | awk '{print $4}' | cut -d/ -f1 | cut -d'.' -f4 | cut -d'2' -f2);
  # be sure time server is running on DHCP server
  currentTime=`date +%Y-%m-%d.%H:%M`
   
  mv env-chamber-testing.log trx-board-$boardID-env-chamber.log.$currentTime
  mv cpu-temp.log trx-board-$boardID-env-cpu-temp.log.$currentTime
}
 
finish_test_now() {
  echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) Ctrl+C Detected: End of the test"
  precced=0;
  #kill -INT $vid_pid $str_pid $log_pid;
  sleep 3;
  test_status=`cat env-chamber-testing.log | grep -i "error" | grep -v -e "0 errors" -e "no corrected errors"`
  if [ -z "$test_status" ]
  then
    echo "*********TEST PASS*********"
  else
    echo "*********TEST FAIL*********"
    echo "List of detected errors:"
    cat env-chamber-testing.log | grep -i "error" | grep -v -e "0 errors" -e "no corrected errors" -e "List of detected errors:"
  fi
  updateLogFiles
  exit;
}
  
# kill all processes if Ctrl+C is detected
trap finish_test_now 2
 
# play a video stream from HDMI input - testing also HDMI output
gst-launch-1.0 -q imxv4l2src ! autovideosink &
 
# stressapptest - one thread CPU, one thread memory, sata thread (if possible)
if [ "${basic}" -eq "1" ]; then
  stress-ng --cpu 2 --vm 4 &
  str_pid=$!
fi
if [ "${pro}" -eq "1" ]; then
  stress-ng --cpu 4 --vm 4 &
  str_pid=$!
fi
if [ "${max}" -eq "1" ]; then
  stress-ng --cpu 4 --vm 4 &
  str_pid=$!
fi
echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) Starting stressapptest with PID: " $str_pid
  
proceed=1
# create test files
file1_path=`mktemp`
file2_path=`mktemp`
file1=`basename $file1_path`
file2=`basename $file2_path`

dd if=/dev/urandom of=$file1_path bs=1024 count=10000
dd if=/dev/urandom of=$file2_path bs=1024 count=10000
 
cp1_from="/media/mmc0/"
cp1_to="/media/usb0/"
 
cp2_from="/media/usb0/"
cp2_to="/media/usb1/"
 
#copy files in case they are missing
cp $file1_path $cp1_from
cp $file1_path $cp1_to
cp $file2_path $cp2_from
cp $file2_path $cp2_to
  
while [ $proceed -eq 1 ]
do
 
  ping -q -c1 127.0.0.1 >> env-chamber-testing.log
  if [ $? -ne 0 ]
  then
    echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) ERROR: Ping failed"
  else
    echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) Ping OK"
  fi
  
  cp1_done=`ps | grep $cp1_pid | grep cp`
  if [ -z "$cp1_done" ]; then # copy finished
    if cmp -s $cp1_from$file1 $cp1_to$file1; then
      echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) PASS: Copying file from $cp1_from to $cp1_to successful"
    else
      echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) ERROR: Difference between files on $cp1_from and $cp1_to detected"
    fi
    cp1_temp=$cp1_from # swap destinations
    cp1_from=$cp1_to
    cp1_to=$cp1_temp
      
    rm $cp1_to$file1 # remove destination file
      
    cp $cp1_from$file1 $cp1_to$file1 &
    cp1_pid=$!
    echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) Started copying file from $cp1_from to $cp1_to"
  fi
    
  cp2_done=`ps | grep $cp2_pid | grep cp`
  if [ -z "$cp2_done" ]; then # copy finished
    if cmp -s $cp2_from$file2 $cp2_to$file2; then
      echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) PASS: Copying file from $cp2_from to $cp2_to successful"
    else
      echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) ERROR: Difference between files on $cp2_from and $cp2_to detected"
    fi
    cp2_temp=$cp2_from # swap destinations
    cp2_from=$cp2_to
    cp2_to=$cp2_temp
      
    rm $cp2_to$file2 # remove destination file
      
    cp $cp2_from$file2 $cp2_to$file2 &
    cp2_pid=$!
    echo "$(date +\%Y/\%m/\%d-\%T)($(date +\%Z)) Started copying file from $cp2_from to $cp2_to"
  fi
  
done

The original article can be accessed on the iMX6Rex.com website.