Embedded module TQMa8MxNL - YOCTO Linux BSP documentation

Play Audio on MBa8Mx

A simple test sound can be played with the commandline tool speaker-test.
Headphones or active speakers have to be connected to X13 on MBa8Mx.

speaker-test --channels 2 --test wav

You can also play your own audio files using aplay

aplay <file>

e.g.

aplay test.wav

Record Audio via Line-In on MBa8Mx

arecord -f cd test.wav

There are three GPIO buttons on the MBa8Mx. They are bound to the gpio-keys driver, and can be tested with the evtest tool.

The buttons are available in the sysfs via the device /dev/input/event0 and can be tested with the evtest tool.

evtest /dev/input/event0

The STKa8MxNL supports DVFS (dynamic voltage and frequency scaling, by default the governor ondemand is set. Governors are power schemes for the CPU. Only one may be active at a time.

You can change the actual governor with the following command:

cpufreq-set -g <governor>
(e.g. cpufreq-set -g performance)

Disable CPU Core temporarily

At runtime it is possible to disable multiple CPU cores via the Linux sysfs. On a system that has four CPU cores, the maximum of three cores can be disabled. To disable the a CPU core value 0 must be written to the CPU core specific file /sys/devices/system/cpu/cpu<N>/online where <N> is the number of the Core, the counting starts at zero.
e.g. disable CPU core 4:

echo 0 > /sys/devices/system/cpu/cpu3/online

To check which CPU core(s) are currently enabled the following command can be used:

grep "processor" /proc/cpuinfo

The CPU core can be enabled again by writing the value 1 to /sys/devices/system/cpu/cpu<N>/online.

e.g. enable CPU core 4:

echo 1 > /sys/devices/system/cpu/cpu3/online

setenv addcpu maxcpus=${cpu_num}

setenv cpu_num 2

The STKa8MxNL Starterkit provides one Gigabit Ethernet interfaces.

setenv ipaddr <ipaddr> 
(e.g.: setenv ipaddr 192.168.100.111)
setenv netmask <netmask> 
(e.g.: setenv netmask 255.255.255.0)

ip link set eth0 up

ip link set eth0 down

ip addr show eth0

 
ip -s link show eth0 

ip addr add 192.168.1.100/24 dev eth0

ip -s link

ip route add default via 192.168.1.1 dev eth0

udhcpc -i eth1 

Run GPU benchmark with connected display and loaded device tree in fullscreen mode:

glmark2-es2-wayland --fullscreen

An overview of the onboard i2c devices is available here

i2c dev 0

i2c probe

i2cdetect 2

TQ offers an optional LVDS Display kit for the STKa8MxNL. Each Display can be used on its own by using the corresponding device tree. To allow reusage, the support for each display is separated in a dtsi fragment.

The DIP Switch S9-4 must be OFF.

To bring up the display the U-Boot environment has to be adapted accordingly.

1. Interrupt boot process in U-boot
2. Set U-Boot environment variable fdt_file with the command setenv fdt_file imx8mn-mba8mx-lcdif-lvds-tm070jvhg33.dtb
3. Save the envrionment by executing the saveenv command

Hardware Setup

Instructions for setting up and connecting the camera can be found in the Camera QuickStartGuide:
MIPI-CSI Quick start guide

Software Setup

The following software example displays the live image of the camera on the HDMI interface of the starter kit.
To view the live image, an HDMI monitor must be connected.

setenv fdt_file imx8mp-mba8mpxl-hdmi-imx327.dtb

saveenv

boot

yavta -f SRGGB10 -s 1280x720 /dev/video0

gst-launch-1.0 v4l2src device=/dev/video0 force-aspect-ratio=false ! video/x-bayer,format=rggb,bpp=10,width=1280,height=720,framerate=25/1 ! bayer2rgbneon show-fps=t reduce-bpp=t ! autovideoconvert ! autovideosink sync=false

setenv fdt_file imx8mp-mba8mpxl-hdmi-ov9281.dtb

saveenv

boot

yavta -f Y8 -s 1280x800 -c20 /dev/video0

gst-launch-1.0 v4l2src device=/dev/video0 ! videoconvert ! autovideosink -v sync=false

To set the hardware clock to the actual time and date use the following commands:

date -s [YYYY.]MM.DD-hh:mm[:ss]
hwclock -w

The MBa8Mx has two SPI interfaces. They can be found on the extension headers and can be tested with a loopback test.

echo -n -e "\x01\x0F" | spi-pipe -d <spi interface> -s 10000000 | hexdump
(e.g. echo -n -e "\x01\x0F" | spi-pipe -d /dev/spidev1.0 -s 10000000 | hexdump)

The file /etc/ssh/sshd_config is used to configure the SSH service. To be able to login with a password as user root change the following lines in the Authentication section

PermitRootLogin prohibit-password

to

PermitRootLogin yes 

and

#PasswordAuthentication yes

to

PasswordAuthentication yes

After altering the SSH configuration, the SSH service must be restarted to apply the new configuration:

systemctl restart sshd.socket

To setup a password for a user, execute the command passwd <username>, e.g. passwd root for the default user root, and set your password. Afterwards execute the login command to login the user with the new password.

The STKa8MxNL has two temperature, one is located on the TQMa8MxNL SOM and the other is located on the MBa8Mx baseboard.

Read TQMa8MxNL Temperature Sensor

cat /sys/devices/platform/soc@0/30800000.bus/30a20000.i2c/i2c-0/0-001b/hwmon/hwmon0/temp1_input

Read MBa8Mx Temperature Sensor

cat /sys/devices/platform/soc@0/30800000.bus/30a30000.i2c/i2c-1/1-001f/hwmon/hwmon1/temp1_input

Read CPU internal Temperature Sensor
The i.MX8MxNL CPU has an internal TMU that supports one thermal zone, it can be read by the command below:

Thermal zone0

cat /sys/devices/virtual/thermal/thermal_zone0/temp

With lsusb you can see all connected usb devices. To mount a partition of an usb stick you can excute mount /dev/<partition> <mount dir> (e.g. mount /dev/sdb1 /mnt). This will mount the first partition of sdb to /mnt. To unmount the device execute umount <mount dir> (e.g. umount /mnt).

The STKa8MxNL has two user controllable LEDs, the behavior of these LEDs can be selected by several triggers.

The user LED's are located in /sys/devices/platform/gpio-leds/leds/.
To change the behaviour a specific LED, the value in the file trigger must be overwritten.

The following values are valid:

For example set the trigger of led1 to heartbeat

echo heartbeat > /sys/class/leds/led1/trigger