Igor: Created page with "=Device Tree= == Available Device Tree Files == The current release includes the following '''dtb''' files: {| class="wikitable" style="text-align:left;" |- | align="center" |..."

2025-11-25T11:32:23Z

Created page with "=Device Tree= == Available Device Tree Files == The current release includes the following '''dtb''' files: {| class="wikitable" style="text-align:left;" |- | align="center" |..."

New page

=Device Tree=
== Available Device Tree Files ==
The current release includes the following '''dtb''' files:
{| class="wikitable" style="text-align:left;"
|-
| align="center" | '''DTB'''
| align="center" | '''Hardware Configuration and Features'''
| align="center" | '''Jumpers/Connectors Settings'''
|-
| align="" |ucm-imx91.dtb
| align="" |default hardware configuration
| align="" |
|-
|}

==Set device tree==
The current release provides two methods to switch between dtb files:
* U-Boot environment
The U-boot '''fdtfile''' variable contains the device tree name that will be loaded into the RAM.
This variable can be changed by:
{| class="wikitable" style="text-align:left;"
|-
| align="" | '''Environment'''
| align="" | '''Command'''
|-
| align="" |U-Boot
| align="" |setenv fdtfile <fdt_file_name>; saveenv;
|-
| align="" |Linux
| align="" |fw_setenv fdtfile <fdt_file_name>
|-
|}
* GRUB environment (if the image was created with the meta-compulab-uefi layer)
{| class="wikitable" style="text-align:left;"
|-
| align="" | '''Environment'''
| align="" | '''Command/Procedure'''
|-
| align="" |GRUB Boot Menu
| align="" |Goto "Advanced Boot Options" and choose a device tree from the provided dtb list.
|-
| align="" |Linux
| align="" |grub-editenv /boot/grub/grubenv set fdtfile=<fdt_file_name>
|-
|}

= Serial Console =
UCM-iMX91 provides serial console on UART1.
SB-UCMIMX91 evaluation carrier-board exposes the console UART via CP2104 serial-to-USB bridge on connector [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | '''P16''']].
== Connecting to a host PC ==
# Use a micro-USB cable to connect the console connector '''P16''' to a USB port on your host PC.
# Make sure the CP2104 driver is available with your operating system, otherwise install CP2104 driver onto the host PC from https://www.silabs.com/documents/public/software/CP210x_Windows_Drivers_with_Serial_Enumeration.zip
# Identify the host PC interface and port number that will be used for communication with the UCM-iMX91 evaluation kit:
#* In most Linux PCs, the serial port will be denoted as one of the following (where n is a positive integer): /dev/ttyUSB0, /dev/ttyUSB1 ... /dev/ttyUSBn
#* In Windows PCs, the serial port usually will be denoted as one of the following (where n is a positive integer): COM1, COM2 ... COMn
# Start a terminal emulation program (such as [https://www.putty.org/ PuTTY] on Windows or minicom on Linux).
# In the port configuration section of the terminal emulation program select the port identified in previous step and set the following serial port parameters:
<blockquote>
{{:SB-SOM: serial port parameters table}}
</blockquote>

= USB =
UCM-IMX91 features two USB2.0 ports that are derived from the i.MX91 USB sub-system. 
On SB-UCMIMX91 evaluation carrier-board USB ports are available on the following connectors:

{| class="wikitable" style="text-align:left;"
|-
| align="center" | '''USB port#'''
| align="center" | '''HW setting'''
| align="center" | '''Connector'''
| align="center" | '''Mode'''
|-
| align="center" |1
| align="" |'''P21''' is not used
| align="" |type-A '''J5'''
| align="center" |host
|-
| align="center" |1
| align="" |'''P21''' connected to USB host
| align="" |micro-USB '''P21'''
| align="center" |device
|-
| align="center" |2
| align="" |jumper '''E11''' is open
| align="" |type-A '''J6'''
| align="center" |host
|-
| align="center" |2
| align="" |jumper '''E11''' is closed
| align="" |mini-PCIe '''P18'''
| align="center" |host
|}

== USB #1 in device mode ==
USB #1 port can be operated in device mode when connected to a host machine using connector '''P21'''.
Available gadgets for the UBS #1 in device mode:
{| class="wikitable" style="text-align:left;"
|-
|align=""|'''USB gadget'''
|align=""|'''SOM command'''
|-
|align=""|usb serial device
|align=""|modprobe g_serial
|-
|align=""|usb network device
|align=""|modprobe g_ether
|-
| align="" |usb mass storage device
| align="" |modprobe g_mass_storage file=/dev/sdX
|-
|}

=CAN bus=
UCM-iMX91 features two Flexible Controller Area Network (FLEXCAN) modules.
SB-UCMIMX91 evaluation carrier-board exposes one CAN bus interface on connector [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | '''J21''']].

* Configure both CAN interface bit-rate to 1 Mbit/sec:
<pre>
ip link set can0 up type can bitrate 1000000
</pre>

* On one system, dump all received data frames as well as error frames:
<pre>
candump any,0:0,#FFFFFFFF

can0 111 [8] 11 22 33 44 55 66 77 88
can0 11111111 [8] 11 22 33 44 55 66 77 88
...
can0 03FF0983 [8] D7 61 FF 03 C1 F7 C1 34
can0 19C34D32 [8] F7 5A C2 73 AD 0E 3F 0B
can0 0675E391 [4] 2B 2D D3 49
can0 13091C55 [8] 99 32 EC 77 27 81 49 0B
can0 098D67CF [8] 22 50 AB 48 AD 7F F4 26
can0 05263FEC [5] 1B 4C 02 45 6E
can0 12B30E20 [0]
can0 1F191DF9 [1] C5
can0 1EB0B18F [8] 3E 3F DA 57 C2 FE 73 58
can0 1E5C64D9 [5] 6F 0D B3 63 6A
can0 1E1DE3F9 [8] 96 48 AC 79 4E 00 27 71
can0 0E1A11B7 [8] 75 81 70 7C 86 79 A7 77
can0 05F8FD8B [7] 33 F9 9B 1E 77 3D 1F
can0 1E155FCD [8] E6 BA F8 58 ED 6D C8 10
can0 1D91DF9E [8] 5D 29 82 7B 97 1D AB 5C
can0 11FB3CDA [3] 14 65 C3
can0 091352C0 [2] 2C ED
...
</pre>

On second system:
* Send standard CAN frame:
<pre>
cansend can0 111#1122334455667788
</pre>

* Send extended CAN frame:
<pre>
cansend can0 11111111#1122334455667788
</pre>

* CAN frames (extended mode) generator, random payload, interval between two successive flames 50 msec:
<pre>
cangen -g 50 -e -D r -v can0

can: raw protocol (rev 20170425)
...
can0 03FF0983#D7.61.FF.03.C1.F7.C1.34
can0 19C34D32#F7.5A.C2.73.AD.0E.3F.0B
can0 0675E391#2B.2D.D3.49
can0 13091C55#99.32.EC.77.27.81.49.0B
can0 098D67CF#22.50.AB.48.AD.7F.F4.26
can0 05263FEC#1B.4C.02.45.6E
can0 12B30E20#
can0 1F191DF9#C5
can0 1EB0B18F#3E.3F.DA.57.C2.FE.73.58
can0 1E5C64D9#6F.0D.B3.63.6A
can0 1E1DE3F9#96.48.AC.79.4E.00.27.71
can0 0E1A11B7#75.81.70.7C.86.79.A7.77
can0 05F8FD8B#33.F9.9B.1E.77.3D.1F
can0 1E155FCD#E6.BA.F8.58.ED.6D.C8.10
can0 1D91DF9E#5D.29.82.7B.97.1D.AB.5C
can0 11FB3CDA#14.65.C3
can0 091352C0#2C.ED
...
</pre>

= Bluetooth =
UCM-iMX91 features Bluetooth connectivity implemented with an NXP 88W8997 module. 

{{Note|Before working with Bluetooth, please ensure that Bluetooth antenna is connected to the SOM.}}

To start '''bluetoothctl''' use the following command:
<pre>
bluetoothctl
</pre>

To start the scan process use the following commands:
<pre>
[bluetooth]# default-agent
[bluetooth]# power on
[bluetooth]# scan on
</pre>

Bluetooth device should be turned on and visible. Its MAC-adress and name should appear in '''bluetoothctl''' in following format:
<pre>
[CHG] Device AA:BB:CC:DD:EE:FF Name: Device_Name
</pre>

To pair with the Bluetooth device use the following command:
<pre>
pair AA:BB:CC:DD:EE:FF
</pre>

Where '''AA:BB:CC:DD:EE:FF''' is MAC-adress of the Bluetooth device.

To quit '''bluetoothctl''' use the following command:
<pre>
[Device_Name]# quit
</pre>

=Cellular Modem=
UCM-IMX91 Yocto includes support for Quectel EC25 mini-PCIe cellular modem that can be installed into the evaluation kit.

* Install the modem module into the mini-PCIe socket [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | '''P18''']]
* Close jumper [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | '''E11''']]
* Connect a cellular antenna to the main antenna connector on the modem
* Install an active SIM card into SIM socket [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | '''P20''']]
* Boot to linux

Run the following command to verify that the modem is detected correctly:
<pre>
root@ucm-imx91:~# lsusb
Bus 001 Device 002: ID 2c7c:0125 Quectel Wireless Solutions Co., Ltd. EC25 LTE modem

root@ucm-imx91:~# mmcli -L
/org/freedesktop/ModemManager1/Modem/0 [QUALCOMM INCORPORATED] QUECTEL Mobile Broadband Module
</pre>
Obtain <apn> of your sim card company ,e.g. rl.internet

Establish connection:
<pre>
root@ucm-imx91:~# nmcli connection add type gsm ifname '*' con-name CellularCon apn <apn>
root@ucm-imx91:~# nmcli connection
NAME UUID TYPE DEVICE
CellularCon a1620622-8588-4349-b3fc-66be79fbbede gsm cdc-wdm0
</pre>
Allow up to a minute to connect to wireless network and make sure modem state is connected:
<pre>
root@ucm-imx91:~#mmcli -m 0
</pre>
To test the wireless interface run:
<pre>
root@ucm-imx91:~#ping -c 5 dns.google -I wwan0
</pre>

=UART=
The following table outlines default UART routing when UCM-iMX91 is used with the SB-UCMIMX91 carrier-board:
{| class="wikitable" style="text-align:left;"
|-
| align="center" | '''UCM-iMX91 port'''
| align="center" | '''Linux device'''
| align="center" | '''on SB-UCMIMX91 carrier-board'''
|-
| align="center" |UART1
| align="center" |/dev/ttyLP0
| align="" |converted to serial-over-USB debug console, micro-USB connector [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | P16]]
|-
| align="center" |UART2
| align="center" |/dev/ttyLP1
| align="" |converted to RS232, DB9 connector [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | P17]]
|-
| align="center" |UART5
| align="center" |/dev/ttyLP4
| align="" |routed to 100-mil header [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | P3]]
|-
| align="center" |UART7
| align="center" |/dev/ttyLP6
| align="" |converted to RS485, terminal block [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | J22]]
|-
|}

'''Example: testing UART5'''
* Short pin P3-1 (UART5-RX) with P3-3 (UART5-TX) on SB-UCMIMX91 to create a loop-back.
* Run the following commands:
stty -F /dev/ttyLP4 1:0:1cb2:0:3:1c:7f:15:4:5:1:0:11:13:1a:0:12:f:17:16:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0:0
cat /dev/ttyLP4 &
echo hello > /dev/ttyLP4
The "hello" string should appear on the terminal.


=I2C=
The following I2C buses and devices are present when UCM-iMX91 is used with the SB-UCMIMX91 carrier-board:
{| class="wikitable" style="text-align:left;"
|-
| align="center" | '''Device'''
| align="center" | '''I2C bus in Linux'''
| align="center" | '''Address'''
| align="center" | '''HW port in UCM-iMX91'''
|-
| align="" |UCM-iMX91 EEPROM
| align="center" |0
| align="center" |0x50
| align="center" |I2C1 (internal)
|-
| align="" |UCM-iMX91 RTC
| align="center" |0
| align="center" |0x69
| align="center" |I2C1 (internal)
|-
| align="" |UCM-iMX91 PMIC
| align="center" |1
| align="center" |0x25
| align="center" |I2C2 (internal)
|-
| align="" |GPIO extender on SB-UCMIMX91 for on-board control signals
| align="center" |2
| align="center" |0x20
| align="center" |I2C3
|-
| align="" |Camera module control on SB-UCMIMX91 connector P9
| align="center" |2
| align="center" |0x42
| align="center" |I2C3
|-
| align="" |SB-UCMIMX91 EEPROM
| align="center" |2
| align="center" |0x54
| align="center" |I2C3
|-
| align="" |Touch-screen controller of MIPI-DSI or LVDS panel on SB-UCMIMX91 connector P8 or P12
| align="center" |2
| align="center" |0x5d
| align="center" |I2C3
|-
|}

To list all mapped devices:
<pre>
# ls /proc/device-tree/soc@0/bus@*/i2c@*/*@* -d -w 1
/proc/device-tree/soc@0/bus@42000000/i2c@42530000/goodix@5d
/proc/device-tree/soc@0/bus@42000000/i2c@42530000/mipi2@42
/proc/device-tree/soc@0/bus@42000000/i2c@42530000/pca9555@20
/proc/device-tree/soc@0/bus@44000000/i2c@44340000/rtc@69
/proc/device-tree/soc@0/bus@44000000/i2c@44350000/pmic@25
</pre>
Note how:
* each node is appended with its address.
* I2C buses order corresponds to the order of their addresses.

e.g. to inspect bus 0, in which we have RTC, run:
# i2cdetect -y 0
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: 50 51 52 53 -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- UU -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
In the above output numbers mark unused devices, UU marks a device that is used by a driver.

Indeed we see RTC in use at offset 0x69.

An example how to dump EEPROM contents:
hexdump -C /sys/devices/platform/soc@0/44000000.bus/44340000.i2c/i2c-0/0-0050/eeprom

=SPI=

Loopback example:

In order to enable SPI device, it needs to be added to the device tree in the following manner:

Set up the kernel source repository by following the instructions in this guide: https://github.com/compulab-yokneam/meta-bsp-imx9/blob/mickledore-6.1.55-2.0/Documentation/linux_kernel_build.md

However, stop before the final command that builds the kernel.

Instead of building the full kernel, run:

make dtbs

Locate the compiled device tree:

arch/arm64/boot/dts/compulab/ucm-imx91-lpspi.dtb

On the UCM-IMX91, identify your boot partition by running:

lsblk

Then, copy the .dtb file to that partition.

Restart your device and interrupt the boot process to access U-Boot. Then run:

setenv fdtfile ucm-imx91-lpspi.dtb; boot

SPI signals location:
<pre>
ECSPI3_MOSI - P3.14
ECSPI3_SCLK - P3.16
ECSPI3_MISO/UART7_RX - U25 pin 1 (beside RS485)
ECSPI3_SSO/UART7_TX - U25 pin 4 (beside RS485)
</pre>

Use jumper cable to connect MOSI and MISO.

On the module, run:
spidev_test -v -D /dev/spidev0.0 -p "hello"

You should see RX same as TX.

=GPIO=
The following table outlines default GPIO assignments when UCM-iMX91 is used with the SB-UCMIMX91 carrier-board:
{| class="wikitable" style="text-align:left;"
|-
| align="center" | '''Signal Name
| align="center" | '''Pin on SB-UCMIMX91'''
|-
| align="center" |GPIO_IO04
| align="center" |P3-20
|-
| align="center" |GPIO_IO05
| align="center" |P3-18
|-
| align="center" |GPIO_IO07
| align="center" |P3-6
|-
| align="center" |GPIO_IO14
| align="center" |P5-4
|-
| align="center" |GPIO_IO15
| align="center" |P5-2
|-
| align="center" |GPIO_IO16
| align="center" |P3-4
|-
|}

Other signals that are reserved for peripheral controls can be reassigned to GPIOs in
arch/arm64/boot/dts/compulab/ucm-imx91-pinctrl.dtsi

== Example: controlling pin GPIO_IO16==
=== Checking the pin info===
gpioinfo -c 0
This lists all GPIO lines in `gpiochip0`, including GPIO_IO16 (line offset 16).

=== Writing to a pin===
Set to high:
gpioset -c 0 --toggle 0 16=1
Set to low:
gpioset -c 0 --toggle 0 16=0

=== Reading the logical level from a pin===
gpioget -c 0 16

=ADC=
i.MX91 SoC features integrated 12 bit analog to digital converter. 
To use the ADC, enable it in device tree e.g. in arch/arm64/boot/dts/compulab/sbc-mcm-imx91.dts:
<pre>
&adc1 {
vref-supply = <&reg_vref_1v8>;
status = "okay";
};
</pre>
Sysfs device controls will appear in:
cd /sys/bus/iio/devices/iio\:device0/
SB-UCMIMX91 exposes ADC signals on 100-mil header '''P3'''.
{| class="wikitable" style="text-align:center;"
|-
| '''Signal Name || '''pin on P3''' || '''sysfs file'''
|-
|ADC_IN0
|9
|in_voltage0_raw
|-
|ADC_IN1
|11
|in_voltage1_raw
|-
|ADC_IN2
|13
|in_voltage2_raw
|-
|ADC_IN3
|15
|in_voltage3_raw
|-
|}
For example, to read voltage from P3-9 run:
cat /sys/bus/iio/devices/iio\:device0/in_voltage0_raw
Expected output is a value in range 0 - 4095 which spans over the voltage range 0 - 1.8V
=Suspend / Resume=
{{note|The operation below requires '''root''' access.}}
*Suspend mode allows minimizing the power consumption.
*To enter suspend mode run:
echo mem >/sys/power/state
*To resume normal operation press shortly the power button [[UCM-iMX91: Evaluation Kit: Hardware Guide#Connector_Locations | '''SW5''']].
*To enter suspend mode with RTC as wakeup source that wakes after 5 seconds run:
rtcwake -s 5 -m mem -d /dev/rtc0
*WiFi device currently doesn't support suspension. see [[UCM-iMX91:_Yocto_Linux:_Known_Issues]]

=CPU temperature=
i.MX91 SoC features an internal temperature sensor which allows to measure the SoC temperature.
Execute the following command to read the current CPU temperature:
<pre>
cat /sys/class/thermal/thermal_zone0/temp
</pre>

= RTC =
UCM-iMX91 features two RTC devices:
* i.MX91 internal RTC ('''rtc0''') - can be used as wake-up source
* AB1805 external RTC ('''rtc1''') - can be used for low current battery powered time keeping

== Internal RTC - rtc0 ==
System information:
<pre>
udevadm info -p /sys/class/rtc/rtc0

P: /devices/platform/soc@0/44000000.bus/44440000.bbnsm/44440000.bbnsm:rtc/rtc/rtc0
N: rtc0
L: -100
S: rtc
E: DEVPATH=/devices/platform/soc@0/44000000.bus/44440000.bbnsm/44440000.bbnsm:rtc/rtc/rtc0
E: DEVNAME=/dev/rtc0
E: MAJOR=251
E: MINOR=0
E: SUBSYSTEM=rtc
E: USEC_INITIALIZED=14959708
E: DEVLINKS=/dev/rtc
</pre>

Wake up:
rtc0 can be used as a wake up source, as a result an '''rtcwakeup''' can be used with this device:
<pre>
rtcwake --device /dev/rtc0 -s 5 -m mem
</pre>

== External RTC - rtc1 ==
System information:
<pre>
udevadm info -p /sys/class/rtc/rtc1

N: rtc1
L: 0
E: DEVPATH=/devices/platform/soc@0/44000000.bus/44340000.i2c/i2c-0/0-0069/rtc/rtc1
E: DEVNAME=/dev/rtc1
E: MAJOR=251
E: MINOR=1
E: SUBSYSTEM=rtc
</pre>

Set the date and write it into the RTC:
<pre>
date -s "16 Jun 2023 12:00:00"

Fri 16 Jun 2023 12:00:00
hwclock --systohc --rtc /dev/rtc1
</pre>

Read the RTC time and date:
<pre>
hwclock --show --rtc /dev/rtc1

2023-06-16 12:01:37.915876+00:00
</pre>

= Device Serial Number=
Product information is stored in on-board EEPROM. 
* To read the product serial number run:
cat /proc/device-tree/product-sn && echo
* To read the product configuration part number run:
cat /proc/device-tree/product-options && echo

=See Also=
* [[UCM-iMX91L: Evaluation Kit: Getting Started|Eval-kit Quick Start Guide]]
* [[UCM-iMX91: Evaluation Kit: Hardware Guide|Eval-Kit Hardware Guide]]

[[Category:Yocto]]
[[Category:UCM-iMX91L]]

UCM-iMX91: Yocto Linux: How-To Guide - Revision history

Igor: Created page with "=Device Tree= == Available Device Tree Files == The current release includes the following '''dtb''' files: {| class="wikitable" style="text-align:left;" |- | align="center" |..."