Connector | Function |
---|---|
X15 | Microphone |
X16 | Line In |
X17 | Line Out |
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
amixer
or alsamixer
The MBa8MPxL has two GPIO buttons, they are bound to the gpio-keys driver.
Reference | Button |
---|---|
S12 | Button 0 |
S13 | Button 1 |
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.
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 |
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
candump can0& cansend can1 5A1#11.2233.44556677.88
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.
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
The TQMa8MPxL Starterkit provides two Gigabit Ethernet interfaces.
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)
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
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.
setenv fdt_file imx8mp-tqma8mpql-mba8mpxl-hdmi.dtb
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.
setenv fdt_file imx8mp-mba8mpxl-lvds-tm070jvhg33.dtb
saveenv
command
Instructions for setting up and connecting the camera can be found in the Camera QuickStartGuide:
MIPI-CSI Quick start guide
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.
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
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
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.
Interface | linux filesystem |
---|---|
SPI1 | /dev/spidev1.0 |
SPI2 | /dev/spidev2.0 |
For the loopback test you need a bridge between SPI_MOSI and SPI_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)
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
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.
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 |
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
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.