del_intern:arm:tqma8mpxl:mba8mp-ras314:linux:armbian:how

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Audio

Audio Connector Overview

Connector	Function
X3	Headphone/Microphone

Audio Connector Location

Play Audio on MBa8MP-RAS314

A simple test sound can be played with the commandline tool speaker-test.
Headphones or active speakers have to be connected to X3 on MBa8MP-RAS314.

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 MBa8MP-RAS314

arecord -f cd test.wav

The audio settings can be altered using amixer or alsamixer

CPU

The MBa8MP-RAS314 supports DVFS (dynamic voltage and frequency scaling, by default the governor schedutil 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)

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

Set ammount of CPU Cores permanently

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 MBa8MP-RAS314 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

dhclient

GPU

Running a GPU benchmark requires a display (HDMI or LVDS) Please keep in mind to set the devicetree properly if LVDS is used.

The benchmark tools are not included in the standard image configuration. In order to use them, they have to be downloaded via APT package manager.

Please note that the glmark2 test requires a Desktop environment, while the kmscube works on both image types.

sudo apt install kmscube

sudo apt install glmark2-es-drm

The benchmark can be started by using the following terminal commands:

Image type	Command
Minimal image	kmscube
Desktop environment	glmark2-es2-drm

HDMI

HDMI is enabled by default on all Armbian images for the MBa8MP-RAS314 board, no further configuration is required.

LVDS

TQ offers an optional LVDS Display kit for the MBa8MP-RAS314. To activate LVDS including the display configuration, the devicetree imx8mp-tqma8mpql-mba8mp-ras314-lvds.dtb has to be set in /boot/extlinux/extlinux.conf in the line beginning with “fdt”

fdt /boot/dtb/freescale/imx8mp-tqma8mpql-mba8mp-ras314-lvds.dtb

To load the LVDS devicetree restart the system.

RTC

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

date -s MMDDhhmmCCYY.ss
hwclock -w

SPI

The MBa8MP-RAS314 has one SPI interface, it is routed to header X1 and can be tested with a loopback test.

SPI Overview

Interface	linux filesystem
SPI3	/dev/spidev3.0

Loopback Test SPI Interface

The loopback test requires a bridge between SPI_MOSI and SPI_MISO:

SPI3: bridge between X1_20 (ECSPI3_MISO) and X1_19 (ECSPI3_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/spidev3.0 -s 10000000 | hexdump)

Temperature Sensors

The MBa8MP-RAS314 has one temperature sensor, which is located on the TQMa8MPxL SOM.

Device	I²C Address
TQMa8MPxL	0x1B

Read TQMa8MPxL Temperature Sensor

cat /sys/devices/platform/soc@0/30800000.bus/30a20000.i2c/i2c-0/0-000001b/hwmon/hwmon2/temp1_in

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.

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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 MBa8MP-RAS314 has two user LEDs, the behavior of these LEDs can be selected by several triggers.

User LED Overview

Reference	LED name	color	linux filesystem
V2	green:	green	/sys/class/leds/green:
V3	yellow:	orange	/sys/class/leds/yellow:

User LED Location

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

The following values are valid:

For example set the trigger of “green:” to heartbeat

echo heartbeat > green:

SSH Connection

Please keep in mind that the following instructions focus on simplicity, not on security.

In order to access the starter kit via SSH, open a terminal under linux or a terminal programme, e.g. PuTTY, and connect to the starter kit with the IP that was assigned to the starter kit by the dhcp client, or in the terminal using

ssh root@mba8mpxl-ras314

When the system is started for the first time, the password “1234” must be used. Afterwards, in the Armbian setup, you can then set your own password.

If several MBa8MPxL-RAS314 boards with the same name are connected to the same network, connection problems may occur using SSH if they are not accessed via the IP address.

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

PermitRootLogin yes

and

#PasswordAuthentication yes

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.