DHCOR STM32MP1 Linux

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U-Boot Bootloader Commands

Activating Device Tree Overlays

Some of the hardware features can be activated with the help of a device tree overlay. To activate a device tree overlay, you have to go into the U-Boot console first. This can be done during the first seconds after startup, by simply hitting any button on a keyboard once the system tells you to do so.
When you are in the bootloder, you can view a list of all available device tree overlays with the following command.
> ls mmc 0:4 /boot
After that, you can select a device tree overlay with the following commands:
To activate CAN support:
> setenv loaddtos '#conf@stm32mp157a-avenger96.dtb#conf@stm32mp157a-avenger96-overlay-fdcan1-x6.dtbo#conf@stm32mp157a-avenger96-overlay-fdcan2-x6.dtbo'
To activate the 96Boards D3Camera Mezzanine Board enter:
> setenv loaddtos '#conf@stm32mp157a-avenger96.dtb#conf@stm32mp157a-avenger96-overlay-ov5640-x7.dtbo'
If you want to make use of the MIPI DSI interface, you can start with an MIPI DSI interface board developed by DH electronics. If you want to use it, simply contact us to find out more about it.
To activate the MIPI DSI Interface enter the following device tree overlay.
> setenv loaddtos '#conf@stm32mp157a-avenger96.dtb#conf@stm32mp157a-avenger96-overlay-644-100-x6-otm8009a.dtbo'
If you want to save your settings, so that you don't have to enter the device tree overlay after every reboot, enter this command:
> saveenv
To reset your device tree overlay, simply override the last settings:
> setenv loaddtos '#conf@stm32mp157a-avenger96.dtb'
Once the device tree overlay is set, you can boot up your board by entering boot:
> boot

Linux Userspace Commands

Logging in after Startup

After booting, you con login as the user "root" without any password. Note, that the standard console is connected to the UART 1 port (96Boards name).
dh-stm32mp1-dhcor-avenger96 login: root

Interacting with GPIOs

An GPIO can be activated with the gpioset command. To find out which GPIO is connected to what gpiochip-device, take a look at the Hardware Section below.
The GPIO "A" can be turned on by
# gpioset gpiochip0 14=1
and off by
# gpioset gpiochip0 14=0

Interacting with the User LEDs

In between the two USB-Host connectors of the Avenger96, you can find four so called User LEDs. These LEDs can be used for simple programming examples and be accessed and manipulated by the user form the userspace.
The LEDs are located under /sys/class/leds.
To disable the blinking of the LED0 hit following command:
# echo none > /sys/class/leds/green:user0/trigger
The LEDs can also be turned on or off permanently by writing either "1" or "0" to the following file:
# echo 1 > /sys/class/leds/green:user0/brightness
# echo 0 > /sys/class/leds/green:user0/brightness

Accessing Devices over I2C

Once you have connected some I2C devices to the Avenger96, you can scan the I2C bus and see if your device is available.
To scan for devices on the I2C-Bus 1 enter the following command:
# i2cdetect -y 1
To write on the device on the address 0x50 to its register number 0x10 the value 0x20 enter the following command:
# i2cset -y 1 0x50 0x10 0x20
To read the data of the device on the address 0x50 at its register 0x10 enter this:
# i2cget -y 1 0x50 0x10
For a dump of the entire registers of the device at address 0x50 enter the following command:
# i2cdump -f 1 0x50

Unsing the internal RTC

Read out the current date and time of the system (not the RTC itself)
# date
Set a specific system time
# date -s "2020-01-30 10:00:00"
Save the current system time to the RTC of the STM32MP1
# hwclock -w
When you allready have stored a date on the RTC and you want to read it out, use the next command. This command only gives back the time, but does not synchronize it with the system time. This is done in the next step.
# hwclock -r
The system time can be synchronised to the RTC by this command:
# hwclock -s

Using the second UART port

If you want to use the second UART Port available on the Low Speed Expansion Connector of the Avenger96, you can access it easily with the tool called minicom
To open up its configuration enter the following command
# minicom -s
Once you've opend minicom, navigate to Serial port setup and change the Serial Device to /dev/ttySTM1.
Now you can hit exit and you are in a terminal which is connected to the second UART port.
To reopen the settings of minicom press CTRL + A and then O on your keyboard.
To close minicom press CTRL + A and then X on your keyboard.

Connecting to a WiFi network

After bootup, you have to enter the following commands:
activating the wlan0 interface
# ifconfig wlan0 up
Enter the SSID and the WPA Key
# wpa_passphrase "YOUR SSID" your-wpa-key > wpa_supplicant.conf
Defining the settings
# wpa_supplicant -B -Dnl8011 -iwlan0 -cwpa_supplicant.conf
After that you should get the message "successfully initialized wpa_supplicant"
Requesting an IP-Address from the DHCP-Server
# udhcpc -i wlan0
Checking your IP Address
# ifconfig

Connecting to a Bluetooth Device

In this example you can see how to connect a bluetooth headset to the Avenger96 and play a song over it.
For this you have to first store a *.wav audiofile in the home directory (/home/root).
First start pulsaudio
# pulseaudio --start
Bring up the Bluetooth Device
# hciconfig hci0 up
Start the Bluetooth configuration tool
# bluetoothctl
Now you are controlling the configuration tool. Here you can start the scanning for bluetooth devices
[bluetooth]# scan on
Once you see the device you like to connect to stop the scanning.
[bluetooth]# scan off
Now Copy the MAC-address of your bluetooth device and pair to it
[bluetooth]# pair xx:xx:xx:xx:xx:xx
Next add it to the list of trusted devices
[bluetooth]# trust xx:xx:xx:xx:xx:xx
Finally connect to it
[bluetooth]# connect xx:xx:xx:xx:xx:xx
Your Headphone should now be connected to the Avenger96, so you can leave the bluetooth configuration tool
[bluetooth]# exit
Now you can start playing your audiofile
# aplay audiofile.wav
When you want to remove your device from the Avenger96, open bluetoothctl again and remove its MAC-address
[bluetooth]# remove xx:xx:xx:xx:xx:xx

Activating the CAN interface

The Avenger96 has two CAN FD ports which can be accessed from the GPIOs on the Low Speed Expansion Connector:
FDCAN 1:
PA12 - TX
PA11 - RX
FDCAN 2:
PB13 - TX
PB5 - RX
To activate them, you have to add a Device Tree Overlay in the bootloader, like mentioned in the beginning of this page.
Once this is done, you have to connect a CAN-Transceiver to the GPIOs and from here you can access the CAN-Bus.
Setup CAN interface with baudrate 500kbit/sec.
# ip link set can0 up type can bitrate 500000
Start to listen on CAN port
# candump can0
Send test message
# cansend can0 100#11.2233.44556677.88
Deinitialize CAN port
# ip link set can0 down

Activating the MIPI CSI Interface

The Avenger96 is compatible with the D3Camera Mezzanine Board available on the 96Boards website.
To activate this Mezzanine Board you have to connect it to the Avenger96 before you power it up. Note, that you also have to access the UART0 which is then available on the Solderpins of the D3Camera Mezzanine board.
Like for CAN you also have to activate the proper device tree overlay as describte in the beginning of this page.
Once the system is booted, you have to connect a display to the Avenger96 via HDMI and then enter the following command.
# XDG_RUNTIME_DIR=/var/run/user/0/ gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-raw,width=1280,height=720,pixelformat=RGB565 ! waylandsink

Mounting a USB Drive

To mount a USB drive connect it to the Avenger96 and mount it with the following command
# mount /dev/sda1 /mnt
Now your USB drive is available under the following directory
# cd /mnt
To unmount the drive enter the following command
# umount /dev/sda1

Formatting and mounting the eMMC

At first you can check all block devices by this command
# lsblk
First partitionate the eMMC device
# cfdisk /dev/mmcblk2
Now select the partitiontable gpt. Then in the menu you can add a new partiton by entering new and then the size of your partition e.g. 7G.
After that enter write and confirm it with yes. Then you can quit this tool.
Now you can format the new partition
# mkfs.ext4 /dev/mmcblk2p1
To access this partition you have to mount it just like an USB-Stick
# mount /dev/mmcblk2p1 /mnt

Read out the ADC Pins

The GPIOs G and H are mapped as ADC pins. These pins can meassure a value from 0 V to 2,9 V. This reference voltage of 2,9 V is driven by the LDO1 of the PMIC.
The value measured is calculated as followed:
Umeassured = ( RAW + OFFSET ) * SCALE
You can read out the values as followed:
GPIO G:
Navigate to its directory
# cd /sys/bus/iio/devices/iio:device0
Read out SCALE
# cat in_voltage_scale
Read out OFFSET
# cat in_voltage_offset
Once you know these two values, you can read the actual ADC value
# cat in_voltage6_raw


GPIO H:
Navigate to its directory
# cd /sys/bus/iio/devices/iio:device1
Read out SCALE
# cat in_voltage_scale
Read out OFFSET
# cat in_voltage_offset
Once you know these two values, you can read the actual ADC value
# cat in_voltage2_raw

Kernel Userspace Interfaces to Access Hardware

The pinmuxing of the DHCOR STM32MP1 can be configured just as needed by you as a customer and therefore the interfaces used in each configuration might be different. However, to give you an easy way to start developing with the DHCOR STM32MP1 you can use the Avenger96 Board, which is the reference design for our DHCOR module. Thus, the interfaces described here, are the configuration for the Avenger96.

Serial (UART) Interfaces

96Boards Name Linux Name Hardware Name
UART 0 /dev/ttySTM1 UART 7
UART 1 (Standard UART) /dev/ttySTM0 UART 4

I²C Interfaces

96Boards Name Linux Name Hardware Name
I2C0 /dev/i2c-1 I2C2
I2C1 /dev/i2c-0 I2C1
OnBoard /dev/i2c-2 I2C4

microSD and eMMC

96Boards Name Linux Name Hardware Name
microSD mmcblk1 SDMMC1
eMMC mmcblk2 SDMMC2

GPIOs

96Boards Name Linux Name Hardware Name
A gpiochip0 14 PA14
B gpiochip1 11 PB11
C gpiochip2 3 PC3
D gpiochip3 8 PD8
E gpiochip3 14 PD14
F gpiochip3 15 PD15
G (mapped as ADC) gpiochip5 12 PF12
H (mapped as ADC) gpiochip5 13 PF13
I gpiochip0 12 PA12
J gpiochip1 5 PB5
K gpiochip0 11 PA11
L gpiochip1 13 PB13


Beside the GPIOs, the Avenger96 has also four user LEDs, which are controlled the same way as the GPIOs.
96Boards Name Linux Name Hardware Name
LED 0 /sys/class/leds/green:user0 PZ7
LED 1 /sys/class/leds/green:user1 PF3
LED 2 /sys/class/leds/green:user2 PG0
LED 3 /sys/class/leds/green:user3 PG1