Embedded module TQMa8MPxL - YOCTO Linux BSP documentation

Audio

Audio Connector Overview

Connector Function
X15 Microphone
X16 Line In
X17 Line Out
The microphone input is not supported in the current BSP version.

Audio Connector Location

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 -D sysdefault:CARD=tqtlv320aic32x

You can also play your own audio files using aplay

aplay <file>

e.g.

aplay test.wav 
Please notice that no audio test files are available in the default image.

Record Audio via Line-In on MBa8MPxL

arecord -f cd test.wav
The audio settings can be altered using amixer or alsamixer

Buttons

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

GPIO Button Overview

Reference Button
S12 Button 0
S13 Button 1

GPIO Button Location

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

CAN

The MBa8MPxL provides the CAN interfaces CAN0 and CAN1.

CAN configuration

DIP switch S10 is used to configure the CAN interfaces CAN0 and CAN1.

Function S10-1 S10-2
CAN-Bus not terminated OFF OFF
not defined (illegal state) OFF ON
not defined (illegal state) ON OFF
CAN-Bus terminated with 120 Ohm ON ON

CAN Loopback

CAN FD can not be automatically configured by systemd machine units due to a limitation in the systemd version in Yocto Zeus,
it can be enabled by the following commands in the shell:
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

CAN0 -> CAN1

candump can0&
cansend can1 5A1#11.2233.44556677.88

CAN1 -> CAN0

candump can1&
cansend can0 5A1#11.2233.44556677.88

CPU

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.

Governor description
performance Run the CPU at the maximum frequency.
powersave Run the CPU at the minimum frequency.
userspace Run the CPU at user specified frequencies.
ondemand Scales the frequency dynamically according to current load. Jumps to the highest frequency and then possibly back off as the idle time increases.
conservative Scales the frequency dynamically according to current load. Scales the frequency more gradually than ondemand.
schedutil Scheduler-driven CPU frequency selection

You can change the actual governor with the following command:

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

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

It is possible to limit the maximium amount of cores with the the maxcpus= parameter in the kernel command line. To add the new parameter a new U-boot variable addcpu has to be created.

setenv addcpu maxcpus=${cpu_num}

The amount of cores is set by the cpu_num variable, for example if cpu num is set to 2 only two cores will be started.

setenv cpu_num 2

Ethernet

The TQMa8MPxL Starterkit provides two Gigabit Ethernet interfaces.

U-Boot

In U-Boot eth0 is configured as default interface. The IP configuration can be done statically or by a DHCP server in the network.

IP configuration via DHCP

For a configuration via a DHCP server, use the dhcp command in U-Boot.

Static IP configuration For a static IP configuration the following, U-Boot environment variables must be set:

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

Linux

Both Ethernet interfaces are activated and configured by systemd-networkd. The configuration files for the interfaces are located in /lib/systemd/network/ these configuration files can be altered to customize the default interface configuration. A documentation of the configuration files can be found here.

eth0 10-eth0.network
eth1 10-eth1.network

For a temporary static configuration the ip command can be used, below some useful ip commands are listed:

Activate a specific interface
e.g. eth0

ip link set eth0 up


Disable a specific interace
e.g. eth0

ip link set eth0 down


Show ip address for a specific interface
e.g. eth0

ip addr show eth0


Show statistic for a specific interface
e.g. eth0

 
ip -s link show eth0 


Set ip address for a specific interface
e.g. eth0

ip addr add 192.168.1.100/24 dev eth0


Show statistic of all interfaces

ip -s link


Set default gateway for a specific interfaces
e.g. set gateway ip 192.168.1.1 for eth0

ip route add default via 192.168.1.1 dev eth0

If a DHCP server is available in the network environment the ip configuration can be received from it. To do so execute the udhcpc command, by default eth0 is used.
To configure another interface via dhcp the parameter -i followed by the interface name e.g. eth1 must be given.
e.g. eth1

udhcpc -i eth1 

GPU

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

glmark2-es2-wayland --fullscreen

HDMI

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

LVDS

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

MIPI-CSI

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.

Camera imx327 (color)

1. Start the Kit and stop in Uboot
2. Select the appropriate Devicetree for the use of the Camera:

setenv fdt_file imx8mp-mba8mpxl-hdmi-imx327.dtb

3. Save the environment to automatically load the selected devicetree for the next launches:

saveenv

4. Boot the kernel:

boot

5. When linux is started, login and configure the cam:

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

6. run the following command to see the camera output on HDMI:

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

Camera ov9281 (monochrome)

1. Start the Kit and stop in Uboot
2. Select the appropriate Devicetree for the use of the Camera:

setenv fdt_file imx8mp-mba8mpxl-hdmi-ov9281.dtb

3. Save the environment to automatically load the selected devicetree for the next launches:

saveenv

4. Boot the kernel:

boot

5. When linux is started, login and configure the cam:

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

6. Run the following command to see the camera output on HDMI:

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

RTC

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

SPI

The MBa8MPxL has two SPI interfaces. They can be found on the extension headers and can be tested with a loopback test.

SPI Overview

Interface linux filesystem
SPI1 /dev/spidev1.0
SPI2 /dev/spidev2.0

Loopback Test SPI Interface

For the loopback test you need a bridge between SPI_MOSI and SPI_MISO:

  • SPI1: bridge between X63_10 (SPI1_MISO) and X63_12 (SPI1_MOSI)
  • SPI2: bridge between X63_9 (SP2_MISO) and X63_11 (SPI2_MOSI)
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)

Temperature Sensors

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

Device I²C Address
TQMa8MPxL 0x1C
MBa8MPxL 0x1B

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
The temperature is shown in millidegrees Celsius.

USB

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).

User LED

The MBa8MPxL has three user controllable LEDs, the behavior of these LEDs can be selected by several triggers.

User LED Overview

Reference LED name color linux filesystem
V55 led0 green /sys/class/leds/led0
V56 led1 green /sys/class/leds/led1
V60 led2 orange /sys/class/leds/led2

User LED Location

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

SSH Connection

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.

  • Last modified: 2024/03/26 18:07