Embedded module TQMa8MPxL - YOCTO Linux BSP documentation

Play Audio on MBa8MPxL

A simple test sound can be played with the commandline tool speaker-test.
Headphones or active speakers have to be connected to X17 on MBa8MPxL.

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 MBa8MPxL

arecord -f cd test.wav

The MBa8MPxL has two GPIO buttons, they are bound to the gpio-keys driver.

The buttons are available in the sysfs via the device /dev/input/event1 and can be tested with the evtest tool.

evtest /dev/input/event1

The MBa8MPxL provides the CAN interfaces CAN0 and CAN1.

ip link set can0 down
ip link set can0 up type can bitrate 500000 sample-point 0.75 dbitrate 4000000 dsample-point 0.8 fd on
ip link set can1 down
ip link set can1 up type can bitrate 500000 sample-point 0.75 dbitrate 4000000 dsample-point 0.8 fd on

Loopback Test CAN Interface

CAN0 -> CAN1

candump can0&
cansend can1 5A1#11.2233.44556677.88

CAN1 -> CAN0

candump can1&
cansend can0 5A1#11.2233.44556677.88

The STKa8MPxL 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 TQMa8MPxL Starterkit provides two 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

The STKa8MPxL supports HDMI. The 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.

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 imx8mp-tqma8mpql-mba8mpxl-hdmi.dtb
3. Save the envrionment by executing the saveenv command

TQ offers an optional LVDS Display kit for the STKa8MPxL. 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.

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 imx8mp-mba8mpxl-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 MBa8MPxL 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 STKa8MPxL has two temperature sensors, one is located on the TQMa8MPxL SOM and the other is located on the MBa8MPxL baseboard.

Read TQMa8MPxL Temperature Sensor

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

Read MBa8MPxL Temperature Sensor

cat /sys/devices/platform/soc@0/30800000.bus/30a20000.i2c/i2c-0/0-001c/hwmon/hwmon1/temp1_input

Read CPU internal Temperature Sensor
The i.MX8MPxL CPU has an internal TMU that supports two thermal zones, both can be read by the commands below:

Thermal zone0

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

Thermal zone1

cat /sys/devices/virtual/thermal/thermal_zone1/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 MBa8MPxL has three 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 led2 to heartbeat

echo heartbeat > /sys/class/leds/led2/trigger