View source for IOT-DIN-IMX8PLUS: Debian Linux: How-To Guide

= Overview =
The default run-time Linux filesystem image for the CompuLab IOT-DIN-IMX8PLUS Internet of Things Gateway is based on Debian GNU/Linux BookWorm.
The default Debian Linux image includes more than 650 software packages. Among them:

* Core system
* Debian package management system
* SSH server and client
* PulseAudio configuration and usage utilities 
* NetworkManager
* ModemManager
* Bluez5 Bluetooth tools and daemons
* Docker

= Serial Console =
IOT-DIN-IMX8PLUS  provides a serial console on the front panel micro-USB '''DBG''' connector.</br>
== Connecting to a host PC ==
# Use a micro-USB cable to connect the Console connector 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 device:
#* 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>

= Connection and Login =
This Debian rootfs comes with a default sudo user ''compulab''.
User password has to be set at the very first login.

<pre>
Compulab Release compulab-imx8mp 3.1 24.02 based on
Debian GNU/Linux 12 compulab-imx8mp ttymxc1

compulab-imx8mp login: compulab
You are required to change your password immediately (administrator enforced).
New password: 
Retype new password: 
</pre>

To login into the Linux system, use a terminal emulator as described [[IOT-DIN-IMX8PLUS: Debian Linux: How-To Guide#Serial Console|here]], or connect through the network (ssh).

= Package Management =
The IOT-DIN-IMX8PLUS Debian Linux image includes everything required to use the Debian package management utilities.<br>
Use [http://linux.die.net/man/8/apt apt] and [https://linux.die.net/man/1/dpkg dpkg] for managing software packages.

= Device Serial Number and Configuration =
Product information is stored in on-board EEPROM.<br>
* To read the product serial number, issue the folowing command:
<pre>
compulab@compulab-imx8mp:/$ cat /proc/device-tree/baseboard-sn
1240509004602
</pre>

'''Note''' "-" sign which appears on the label is intentionally replaced by "0"

* To read the product configuration part number, issue the following command:
<pre>
compulab@compulab-imx8mp:/$ cat /proc/device-tree/baseboard-options
C1800QM-D4-N32-JEG25G-XL
</pre>

= Device Tree =
== Available Device Tree Files ==
IOT-DIN-iMX8PLUS Debian package includes the following dtb files:
{| class="wikitable" style="text-align:left;"
|-
| align="center" | '''''<fdt_file_name>'''''
| align="center" | '''Description'''
| align="center" | '''Remarks'''
|-
| align="" |''iotdin-imx8p.dtb''
| align="" |default hardware configuration
| align="" |
|-

|}

== Set a device tree ==
IOT-DIN-iMX8PLUS Debian 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="" |<code>setenv fdtfile <fdt_file_name>; saveenv;</code>
|-
| align="" |Linux
| align="" |<code>fw_setenv fdtfile <fdt_file_name></code>
|-
|}
<!-- * GRUB environment
{| 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="" |<code>grub-editenv /boot/EFI/BOOT/grubenv set fdt_file=<fdt_file_name></code>
|-
|}
-->

= Docker =
The [https://docs.docker.com/engine/ Docker Engine] is preinstalled.
* The following command downloads a test image and runs it in a container. The container sample prints a message and exits.
<pre>
compulab@compulab-imx8mp:~$ sudo docker run -it ubuntu
latest: Pulling from library/ubuntu
aa21f24e1940: Pull complete
...
Digest: sha256:e3f92abc0967a6c19d0dfa2d55838833e947b9d74edbcb0113e48535ad4be12a
Status: Downloaded newer image for ubuntu:latest
root@0d6b133a7a93:/# cat /etc/issue
Ubuntu 24.04 LTS \n \l
</pre>

= Cellular Modem =
IOT-DIN-IMX8PLUS cellular interface is implemented with a mini-PCIe cellular modem module and a
nano-SIM socket. 
<br>
Cellular module is an optional module and should be pre-installed into the gateway. Verify your gateway configuration for modem functionality.
<br>
<br>
To set up IOT-DIN-IMX8PLUS for cellular functionality, insert a tray with active SIM card into designated socket. Please refer to [https://www.compulab.com/products/iot-gateways/iot-din-imx8plus-industrial-iot-gateway/#devres IOT-DIN-IMX8PLUS user's manual] for details.<br>
Cellular antenna should be connected to SMA connector '''B''' on the front panel.

== Cellular Connection ==
The [https://manpages.debian.org/testing/modemmanager/mmcli.8 ModemManager] can be used to log into almost any Internet Service Provider with simple configuration setup.

In the following example:
* Replace '''ISP-APN''' with the APN name of the cellular provider.
<pre>
compulab@compulab-imx8mp:~$ sudo nmcli connection add type gsm ifname '*' con-name CellularCon apn <ISP-APN>
</pre>
* Connect cellular network
<pre>
compulab@compulab-imx8mp:~$ sudo nmcli connection up CellularCon
</pre>
* Disconnect cellular network
<pre>
compulab@compulab-imx8mp:~$ sudo nmcli connection down CellularCon
</pre>

= GPS =
IOT-DIN-IMX8PLUS features an optional GPS interface implemented with the cellular modem module.</br>
Cellular module is an optional module and should be pre-installed into the gateway. Verify your gateway configuration for modem functionality.

== GPS antenna ==

A GPS antenna is required for GPS operation. GPS antenna is not included with IOT-DIN-IMX8PLUS. Any active GPS antenna with a male SMA connector can be used with IOT-DIN-IMX8PLUS.</br>
GPS antenna should be attached to SMA connector '''A''' on the gateway.<br>
{{Note|GPS antenna should be positioned at least 1m away from the gateway}}

== Using GPS ==
The [https://manpages.debian.org/jessie/gpsd-clients/cgps.1.en.html cgps] client can be used to display the GPS information. <br>
The [https://manpages.debian.org/testing/modemmanager/mmcli.8 ModemManager] can be used to check the modem status.
For example, the following command shows the presence of the modem and the id of its interfaces.
<pre>
root@compulab-imx8mp:~# mmcli -m 0
</pre>

The cgps client utility depends on the gpsd daemon (starts automatically after the initialization command is performed).
* Initialization of the GPS interface:
<pre>
root@compulab-imx8mp:~# sed -i "/^DEVICES=.*/c\DEVICES=\"/dev/ttyUSB1\"" /etc/default/gpsd
</pre>

* Enable the GPS with the following AT commands:
<pre>
root@compulab-imx8mp:~# echo AT+QGPS= 1 | socat - /dev/ttyUSB2,crnl
</pre>
* Full power cycle is required before using GPS. Shut down the gateway, remove main DC power for at least 20 sec and restart.
* Start the cgps client to display GPS information.

The synchronization process might take a few minutes. 

<pre>
root@compulab-imx8mp:~# cgps
┌───────────────────────────────────────────┐┌─────────────────────────────────┐
│    Time:       2024-05-04T14:13:30.000Z   ││PRN:   Elev:  Azim:  SNR:  Used: │
│    Latitude:    32.65985123 N             ││  71    29    123    22      Y   │
│    Longitude:   35.10027205 E             ││  85    27    047    22      Y   │
│    Altitude:   102.700 m                  ││                                 │
│    Speed:      0.00 kph                   ││                                 │
│    Heading:    128.7 deg (true)           ││                                 │
│    Climb:      6.00 m/min                 ││                                 │
│    Status:     3D FIX (53 secs)           ││                                 │
│    Longitude Err:   n/a                   ││                                 │
│    Latitude Err:    n/a                   ││                                 │
│    Altitude Err:    +/- 18 m              ││                                 │
│    Course Err:      n/a                   ││                                 │
│    Speed Err:       n/a                   ││                                 │
│    Time offset:     -3.682                ││                                 │
│    Grid Square:     KM72np                ││                                 │
└───────────────────────────────────────────┘└─────────────────────────────────┘
</pre>

* Disable the GPS with the following AT commands:
<pre>
root@compulab-imx8mp:~# echo AT+QGPSEND | socat - /dev/ttyUSB2,crnl
</pre>

= Industrial Interfaces =
IOT-DIN-IMX8PLUS implements following industrial interfaces on the 16-pin industrial terminal block:
<br>
* 1x RS232 (2-wire)
* 1x RS485 (half-duplex)
* 1x CAN 2.0B
* 2x digital inputs + 2x digital outputs.

Please refer to Industrial I/O Connector pin-out for more details.

Industrial I/O modules do not require any special configuration.

== CAN bus ==
IOT-DIN-IMX8PLUS CAN 2.0B port is implemented with i.MX8M Plus CAN controller.<br>
CAN signals are routed to industrial I/O connector <br>
Please refer to [https://www.compulab.com/products/iot-gateways/iot-din-imx8plus-industrial-iot-gateway/#devres IOT-DIN-IMX8PLUS user's manual] for Industrial I/O Connector pin-out. <br>

* '''can0''': always enabled and accessible

The following example demonstrates how to configure and use the permanent CAN interface '''can0'''.

=== CAN interface configuration ===
* Configure the CAN interface bit-rate to 1 Mbits/sec:
<pre>
compulab@@compulab-imx8mp:~$ sudo ip link set can0 type can bitrate 1000000
</pre>
* Enable the CAN interface:
<pre>
compulab@@compulab-imx8mp:~$ sudo ip link set can0 up
</pre>
*Expected result: 
<pre>
[...] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready
</pre>

=== Send/Receive packets ===
Use ''cansend'' and ''candump'' utilities to send and receive packets via CAN interface. 
* Send standard CAN frame (on the first device):
<pre>
compulab@@compulab-imx8mp:~$ sudo cansend can0 111#1122334455667788
</pre>

* Send extended CAN frame (on the first device):
<pre>
compulab@@compulab-imx8mp:~$ sudo cansend can0 11111111#1122334455667788
</pre>

* CAN frames (extended mode) generator, random payload, interval between two successive frames 50 msec:
<pre>
compulab@@compulab-imx8mp:~$ sudo cangen -g 50 -e -D r -v can0
...
  can0  1E5137F4#0F.4D.8B.7A.25.4D.DB.21
  can0  1B6C965C#8C.DE.96.58.69.5F.D5.26
  can0  1BD23086#8D.DB.C4.3E.81.57.BA.34
  can0  127B2322#F4.16.31.2E.34.04.62
  can0  1A6366DB#A8.73.C0.37.D8
  can0  03620EE4#
  can0  023AC34D#C6.08.BD.2A.04.B3.BF.43
  can0  1C19AD2E#09.C1.B3.26.23.E5.6A.5A
  can0  02BCA994#48.32.46.7C.F0.3F.29.1E
  can0  08104C67#59.9F.FE.44
  can0  1C280582#6F.D4.9C.38.A5.28.A3
  can0  0BC219EE#D9.2C.05
  can0  04AA80B8#A1.93
  can0  1A3E2392#AD.98
  can0  0025950E#E3.99.38
...
</pre>

* Dump all received data frames as well as error frames:
<pre>
compulab@iot-gate-imx8plus:~$ sudo candump any,0:0,#FFFFFFFF
...
  can0  0CC89C1A   [1]  51
  can0  0A097EFB   [0] 
  can0  02B59BD5   [5]  68 6F 47 64 D9
  can0  03743A1E   [7]  FA BF E4 38 3E BF C8
  can0  13C9B644   [8]  30 FB 60 6F E1 FC 55 65
  can0  018A8975   [0] 
  can0  0C9C8179   [0] 
  can0  011F5D90   [6]  65 DB DD 5A AA F9
  can0  07B7FD18   [6]  CC 96 26 1D 13 7C
  can0  1FBD7177   [8]  69 BF 8D 1E 4C 0D 73 02
  can0  107A7E2D   [2]  25 D3
  can0  12B9E279   [8]  89 77 B7 54 BD 98 83 06
  can0  112A44EA   [8]  9E 95 D9 6B 60 CE B4 52
  can0  0ADF9869   [3]  C8 A0 27
  can0  1580C274   [5]  B2 7A F7 43 04
  can0  06DDDBCC   [7]  AF 19 88 04 E4 D8 95
  can0  127FA5CE   [8]  F7 54 57 20 45 17 3D 12
  can0  09A37893   [0] 
  can0  01BA4332   [6]  0B AF 0C 2E AB 25
  can0  180A8AD5   [5]  68 BE F7 5A C0
  can0  06DC994E   [7]  20 9E E9 7B B8 31 BC
...
</pre>

== RS232 ==
RS232 function is implemented with MAX3221 (or compatible) transceiver interfaced with i.MX8M Plus UART port.

=== Configuration and Access ===
RS232 interface can be accessed in Linux via '''ttyRS232''' tty device.

== RS485 ==
RS485 function is implemented with MAX13488 (or compatible) transceiver interfaced with i.MX8M Plus UART port.

=== Configuration and Access ===
RS485 interface can be accessed in Linux via '''ttyRS485''' tty device.

RS485 has an optional hardware-enabled termination. Please consult with the reference guide for enabling instructions.

=== Modbus RS485 ===
The following example demonstrates how to use RS485 in a Modbus RS485 Network.
IOT-DIN-IMX8PLUS performs as a Master device and queries XY-MD02 temperature and humidity sensor.

==== Software installation ====
Download and install ''modpoll'' - a command line based Modbus master simulator and test utility. 
<pre>
compulab@compulab-imx8mp:~$ wget https://www.modbusdriver.com/downloads/modpoll.tgz -P /tmp/
...
compulab@compulab-imx8mp:~$ sudo tar -xvf /tmp/modpoll.tgz -C /opt/
...
</pre>

==== Device connection ====
* Connect XY-MD02 sensor to appropriate Industrial I/O connector pins as below:
:* '''A+''': XY-MD02 A+ to IOT-DIN-iMX8PLUS I/O PIN 8 
:* '''B-''': XY-MD02 B- to IOT-DIN-iMX8PLUS I/O PIN 7
<pre>
-------------------                            --------------------
|                 |                            |   IOTDIN-IMX8P   |
|                 *--(+)---< <------- 5V-30V   |                  |
|                 |                            |                  |
|                 *--(-)---< <-------- GND     |                  |
| XY-MD02 (RS485) |                            |------            |
|                 *--(A+)--< <--...--> >-(8)-*-|     | Industrial |
|                 |                            | J4  | I/O        |
|                 *--(B-)--< <--...--> >-(7)-*-|     | Connector  |
|                 |                            |------            |
-------------------                            -------------------- 
</pre>

==== Read data ====

* Read temperature once:
<pre>
compulab@compulab-imx8mp:~$ /opt/modpoll/arm-linux-gnueabihf/modpoll -b 9600 -p none -t 3 -c 1 -r 2 -1 /dev/ttyRS485
modpoll 3.10 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2021 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 1, start reference = 2, count = 1
Communication.........: /dev/ttyRS485, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave...
[2]: 250
</pre>

* Poll temperature:
<pre>
compulab@compulab-imx8mp:~$ /opt/modpoll/arm-linux-gnueabihf/modpoll -b 9600 -p none -t 3 -c 1 -r 2 /dev/ttyRS485
modpoll 3.10 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2021 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 1, start reference = 2, count = 1
Communication.........: /dev/ttyRS485, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave... (Ctrl-C to stop)
[2]: 254
-- Polling slave... (Ctrl-C to stop)
[2]: 254
-- Polling slave... (Ctrl-C to stop)
[2]: 254
...
</pre>

* Read humidity once:
<pre>
compulab@compulab-imx8mp:~$ /opt/modpoll/arm-linux-gnueabihf/modpoll -b 9600 -p none -t 3 -c 1 -r 3 -1 /dev/ttyRS485
modpoll 3.10 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2021 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 1, start reference = 3, count = 1
Communication.........: /dev/ttyRS485, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave...
[3]: 515
</pre>

* Poll humidity:
<pre>
compulab@compulab-imx8mp:~$ /opt/modpoll/arm-linux-gnueabihf/modpoll -b 9600 -p none -t 3 -c 1 -r 3 /dev/ttyRS485
modpoll 3.10 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2021 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 1, start reference = 3, count = 1
Communication.........: /dev/ttyRS485_A, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave... (Ctrl-C to stop)
[3]: 894
-- Polling slave... (Ctrl-C to stop)
[3]: 895
-- Polling slave... (Ctrl-C to stop)
[3]: 896
...
</pre>

* Read temperature & humidity once:
<pre>
compulab@compulab-imx8mp:~$ /opt/modpoll/arm-linux-gnueabihf/modpoll -b 9600 -p none -t 3 -c 2 -r 2 -1 /dev/ttyRS485
modpoll 3.10 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2021 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 1, start reference = 2, count = 2
Communication.........: /dev/ttyRS485, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave...
[2]: 263
[3]: 606
</pre>

* Poll temperature & humidity:
<pre>
compulab@compulab-imx8mp:~$ /opt/modpoll/arm-linux-gnueabihf/modpoll -b 9600 -p none -t 3 -c 2 -r 2 /dev/ttyRS485
modpoll 3.10 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2021 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC4
Slave configuration...: address = 1, start reference = 2, count = 2
Communication.........: /dev/ttyRS485_A, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, input register table

-- Polling slave... (Ctrl-C to stop)
[2]: 263
[3]: 545
-- Polling slave... (Ctrl-C to stop)
[2]: 263
[3]: 543
-- Polling slave... (Ctrl-C to stop)
[2]: 263
[3]: 542
...
</pre>

* Read slave address, baudrate, temperature & humidity corrections:
<pre>
compulab@compulab-imx8mp:~$ /opt/modpoll/arm-linux-gnueabihf/modpoll -b 9600 -p none -t 4 -c 4 -r 258 -1 /dev/ttyRS485
modpoll 3.10 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2021 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.

Protocol configuration: Modbus RTU, FC3
Slave configuration...: address = 1, start reference = 258, count = 4
Communication.........: /dev/ttyRS485, 9600, 8, 1, none, t/o 1.00 s, poll rate 1000 ms
Data type.............: 16-bit register, output (holding) register table

-- Polling slave...
[258]: 1
[259]: 9600
[260]: 0
[261]: 0
</pre>

== Digital I/O  ==
IOT-DIN-IMX8PLUS features 2 digital inputs and 2 digital outputs.<br>
2 digital inputs are implemented with the CLT03-2Q3 digital termination following EN 61131-2. 
2 digital outputs are implemented with the TPS272C solid-state relay following EN 61131-2.<br>
Please refer to [https://www.compulab.com/products/iot-gateways/iot-din-imx8plus-industrial-iot-gateway/#devres IOT-DIN-IMX8PLUS user's manual] for Industrial I/O Connector pin-out. <br>
<pre>
----------------
|  IOTD-IMX8P   |
|         ______|     
|        | VIN 1|  +24VDC               
|        | DI0 2|  <<------|
|        | DO0 3|  >>------|
|   T.B. | DI1 4|  <<------|
|        | DO1 5|  >>------|
|        | COM 6|  0V
|        |      |
----------------   
</pre>

{{Note| External voltage supply in the range 6-24VDC must be supplied via DIO_VIN pin for correct operation of digital outputs. Please refer to Industrial I/O Connector pin-out for more details.}}

=== Configuration and Access ===

The example below shows how to access Digital inputs and outputs.

====Digital Outputs ====
* Drive OUT0 pin HI:
<pre>
compulab@compulab-imx8mp:~$ sudo gpioset 3 30=1
</pre>

* Drive OUT1 pin HI:
<pre>
compulab@compulab-imx8mp:~$ sudo gpioset 4 4=1
</pre>

{{Note| ''gpioget'' function doesn't allow to verify the pin state. ''gpioget'' function will always return '''0''' on the OUT1 and OUT2 pin}}

Another way to set the pin state is the usage of ''dioset'' bash script located at ''/opt/iotdin-imx8p/shell''
* Setup alias for more convenient work:
<pre>
compulab@compulab-imx8mp:~$ dioset=/opt/iotdin-imx8p/shell/dioset
</pre>
* Drive OUT0 pin HI:
<pre>
compulab@compulab-imx8mp~$ sudo ${dioset} -m M 0 1
</pre>

* Drive OUT0 pin LOW:
<pre>
compulab@compulab-imx8mp~$ sudo ${dioset} -m M 0 0
</pre>

* Drive OUT1 pin HI:
<pre>
compulab@compulab-imx8mp~$ sudo ${dioset} -m M 1 1
</pre>

* Drive OUT1 pin LOW:
<pre>
compulab@compulab-imx8mp~$ sudo ${dioset} -m M 1 0
</pre>

==== Digital Inputs ====
* Read IN0 pin state:
<pre>
compulab@compulab-imx8mp:~$ sudo gpioget 4 3
</pre>

* Read IN1 pin state:
<pre>
compulab@compulab-imx8mp:~$ sudo gpioget 4 0
</pre>

Another way to set the pin state is the usage of ''dioget'' bash script located at ''/opt/iotdin-imx8p/shell''
* Setup alias for more convenient work:
<pre>
compulab@compulab-imx8mp:~$ dioget=/opt/iotdin-imx8p/shell/dioget
</pre>

* Read IN0 pin state:
<pre>
compulab@compulab-imx8mp~$ sudo ${dioget} -m M 0
</pre>

* Read IN1 pin state:
<pre>
compulab@compulab-imx8mp~$ sudo ${dioget} -m M 1
</pre>

== TPM ==
IOT-DIN-IMX8PLUS assembled with a TPM 2.0 add-on board implemented with Infineon SLB9673.<br>

Verification that the TPM device was created:


* Install the '''tpm2-tools''' package:
<pre>compulab@compulab-imx8mp:~$ sudo apt-get update && sudo apt-get install tpm2-tools</pre>
* Validate basic functionality
<pre>compulab@compulab-imx8mp:~$ sudo tpm2_getrandom 32</pre>
The correct result will be returned generated 32-symbol key.

= RTC =

IOT-DIN-IMX8PLUS RTC is implemented with the AM1805 real-time clock (RTC) chip.</br>
Back-up battery keeps the RTC running to maintain clock and time information whenever the main power supply is not present.

== Accessing and setting the RTC ==
* To access the RTC time and date run:
<pre>
compulab@compulab-imx8mp:~$ sudo hwclock
2024-08-04 12:38:10.577874+00:00
</pre>

* To set the date and write it into the RTC do the following: 
<pre>
compulab@compulab-imx8mp:~$ sudo date -s "31 Dec 2023 10:00:00"
Fri Dec 31 10:00:00 IST 2021
compulab@compulab-imx8mp:~$ sudo hwclock -w
compulab@compulab-imx8mp:~$ sudo hwclock 
2023-12-31 10:00:08.317403+02:00
</pre>

= Watchdog =
IOT-DIN-IMX8PLUS watchdog function is implemented with the i.MX8M Plus watchdog.</br>
By default watchdog is  not configured.
:<pre>compulab@compulab-imx8mp:~$ systemctl show | grep RuntimeWatchdog</pre>
:<pre>RuntimeWatchdogUSec=0</pre>
The value '''RuntimeWatchdogUSec=0''' means watchdog logic is disabled: no watchdog device is opened, configured, or pinged

== Watchdog configuration ==
* Edit ''/etc/systemd/system.conf'' file to configure watchdog related parameters, in particular '''RuntimeWatchdogSec''' and '''ShutdownWatchdogSec'''.
'''#''' comment-out sign should be removed from the relevant line in the file.
:'''RuntimeWatchdogSec''' - specifies the watchdog timeout for runtime services, meaning services that are actively running during normal system operation. The value is in seconds and should be set to a positive integer.<br>
:'''ShutdownWatchdogSec''' - specifies the watchdog timeout for the shutdown process, insuring the system doesn't hang indefinitely during the shutdown. The value is in seconds and should be set to a positive integer.<br>

* Reboot the device
* Verify watchdog configuration
:<pre>compulab@compulab-imx8mp:~$ systemctl show | grep RuntimeWatchdog</pre>
:<pre>RuntimeWatchdogUSec=10s</pre>

== Watchdog testing ==
* Run the following command to simulate kernel panic:
:<pre>compulab@compulab-imx8mp:~$ echo "c" | sudo tee -a /proc/sysrq-trigger</pre>
* As a result, the watchdog is not fed and the system reboots after 10 sec.

= Low Power Modes =
IOT-DIN-IMX8PLUS supports the following low-power modes:
* Sleep mode - RAM content is preserved, and the system can quickly wake up into the operating system. Power consumption in sleep mode is ~0.25W.
* Power-off mode - RAM content is not preserved, and the system will restart into a clean boot. Power consumption in power-off mode is ~0.02W.
IOT-DIN-IMX8PLUS supports two wake-up sources:
* Short press on the power button
* Timer alarm set in internal RTC (rtc1)
{{Important|Only the internal RTC (rtc1) can be used for the wake-up alarm. Main DC power must be present to preserve alarm settings.}}
==== Low power mode examples====
{{Note|Make sure that remote power button event is ignored and does not cause machine power-off: uncomment and set '''HandlePowerKey''' field to '''ignore''' value in the ''/etc/systemd/logind.conf''}}

* Sleep mode with exit by remote power button event:
:<pre>compulab@compulab-imx8mp:~$ echo mem | sudo tee -a /sys/power/state</pre>

* Sleep mode with exit by RTC wake-up call or remote power button event:
:<pre>compulab@compulab-imx8mp:~$ sudo rtcwake --device /dev/rtc1 -s 60 -m mem</pre>
* Power-off mode with boot on RTC wake-up call:
:<pre>compulab@compulab-imx8mp:~$ sudo rtcwake --device /dev/rtc1 -s 60 -m off</pre>
:In this example system reboots after 60 seconds.


{{Note| Low power sleep modes activation can sometimes cause incorrect behavior in cellular modem due to race conditions among their multiple USB devices during wake-up.}}

= LEDs =
IOT-DIN-IMX8PLUS  features two user Bi-Color (Red + Green) LEDs named '''A''' and '''B'''
LEDs are controlled via GPIO pins and can be accessed via [https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-led sysfs] interface.

* LEDs are referred to as ''Green_A'', ''Red_A'', ''Green_B'' and ''Red_B''
* Choose a LED (LED ''B'' Red in this example):
:<pre>compulab@compulab-imx8mp:~$ LED=Red_B</pre>
* Turn the LED ON
:<pre>compulab@compulab-imx8mp:~$ echo "1" | sudo tee -a /sys/class/leds/${LED}/brightness</pre>
* Turn the LED OFF
:<pre>compulab@compulab-imx8mp:~$ echo "0" | sudo tee -a /sys/class/leds/${LED}/brightness</pre>
* Set LED's trigger
:<pre>compulab@compulab-imx8mp:~$ echo "heartbeat" | sudo tee -a /sys/class/leds/${LED}/trigger</pre>

= Push-buttons =

== RST ==

Short press on the RST button forces unconditional reset of the IOT-DIN-IMX8PLUS CPU.

== CMD ==

The CMD button is implemented as gpio-key with code 171 (KEY_CONFIG).<br>
By default, this key is mapped to /dev/input/event1 input device. <br>

Usage example:
<pre>
#!/bin/bash

device="/dev/input/event1"
pressed="code 171 (KEY_CONFIG), value 1"
released="code 171 (KEY_CONFIG), value 0"

press_time=0

evtest "$device" | while read line; do
    if [[ "$line" == *"$pressed"* ]]; then
        press_time=$(date +%s)  # Record the time the button was pressed
    elif [[ "$line" == *"$released"* ]]; then
        release_time=$(date +%s)  # Record the time the button was released
        duration=$((release_time - press_time))  # Calculate press duration
        echo "Button pressed for $duration seconds"
    fi
done
</pre>
[[Category:Linux]]
[[Category:IOT-DIN-IMX8PLUS]]