Embedded module TQMa8MxML - YOCTO Linux BSP documentation



Audio

Audio Connector Overview

Connector Function
X12 Microphone
X14 Line In
X13 Line Out
The microphone input is not supported in the current BSP version.

Audio Connector Location

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

Record Audio via Line-In on MBa8Mx

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

Buttons

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

GPIO Button Overview

Reference Button
S1 Button 0
S2 Button 1
S3 Button 2

GPIO Button Location

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

Ethernet

The STKa8MxML Starterkit provides one Gigabit Ethernet interfaces.

U-Boot

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

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

eth0 10-eth0.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

I2C

An overview of the onboard i2c devices is available here

U-Boot

Select i2c bus device

i2c dev 0

Show all devices connected to the i2c bus currently selected:

i2c probe

Linux

Detect all devices connected to a i2c bus:

i2cdetect 0

LVDS

TQ offers an optional LVDS Display kit for the STKa8MxML. 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.

Interface Device tree
LCDIF imx8mm-mba8mx-lcdif-lvds-tm070jvhg33.dtb

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 imx8mq-mba8mx-lcdif-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 imx8mm-mba8mx-lcdif-lvds-tm070jvhg33-imx327-tqma8mxml-2gb-mba8mx.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 imx8mm-mba8mx-lcdif-lvds-tm070jvhg33-ov9281-tqma8mxml-2gb-mba8mx.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 MBa8Mx 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/spidev0.0
SPI2 /dev/spidev1.0

Loopback Test SPI Interface

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

  • SPI1: bridge between X20_5 (SPI1_MISO) and X20_6 (SPI1_MOSI)
  • SPI2: bridge between X35_33 (SP2_MOSI) and X35_35 (SPI2_MISO)
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)

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.

Temperature Sensors

The STKa8MxML has two temperature sensors, one is located on the TQMa8MxML SOM and the other is located on the MBa8Mx baseboard.

Device I²C Address
TQMa8MxML 0x1B
MBa8Mx 0x1F

Read TQMa8MxML 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.MX8MxML 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
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 MBa8Mx has two user controllable LEDs, the behavior of these LEDs can be selected by several triggers.

User LED Overview

Reference LED name color linux filesystem
V38 led1 green /sys/class/leds/led1
V37 led2 green /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 led1 to heartbeat

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