External Interfaces

Table of contents:

• USB
• Serial ports
• 1-Wire

USB

The device is equipped with 2 USB connectors.

USB1

MicroUSB connector for USB 2.0 is placed on the front panel. The interface can work in both host and device modes. The signal on the connector can be chosen with a switch. Maximum current of the connector is 500 mA.

MicroUSB connector location

USB 1 connection diagram

Function	Processor pin	Default function
5 V USB voltage	F22	USB1_VBUS
USB data differential pair negative	A22	USB1_D_N
USB data differential pair positive	B22	USB1_D_P
USB on the go	AB10	USB1_OTG_PWR

USB2

USB-A connector for USB 2.0 is placed on a side of the device with the interface set up in a host mode. Maximum current of the connector is 1 A.

USB 2 connection diagram

Function	Processor pin	Default function
USB power switch control	F23	USB2_VBUS
USB data differential pair negative	A23	USB2_D_N
USB data differential pair positive	B23	USB2_D_P

Serial ports

The device is equipped with 3 serial port connectors.

RS485-1/2

Baud rate: 50-115200 bps.

Location of the RS485-1/2 connector

Connector pin	Description
A1	RS485 A1
B1	RS485 B1
G	Ground
A2	RS485 A2
B2	RS485 B2

RS485-1/2 connections diagram

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RS485-3/4

Baud rate: 50-115200 bps.

Location of the RS485-3/4 connector

Connector pin	Description
A3	RS485 A3
B3	RS485 B3
G	Ground
A4	RS485 A4
B4	RS485 B4

RS485-3/4 connections diagram

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RS232-1/2

Baud rate: 50-115200 bps.

Location of the RS232-1/2 connector

Connector pin	Description
T1	RS232 TX1
R1	RS232 RX1
T2	RS232 TX2
R2	RS232 RX2

RS232-1/2 connections diagram

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Expander E

The termination resistors are controlled by signals output from the Expander E connected by I2C4 interface with the CPU.

Diagram of serial ports connections

1-Wire

The device is equipped with the 1-Wire interface operating with Maxim sensors. Connector 5 V outputs are secured with a 100 mA fuse.

1-Wire connector and pins

Connector pin	Description
1W	1-Wire data
5V	1-Wire +5 V power
G	Ground

1-Wire connection diagram

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1-Wire bridge

Part number: DS2484

HDMI

The device is equipped with the microHDMI standard connector located on the front panel.

HDMI connector location

Signal	Processor pin	Default function
DSI_TX0_N	A9	MIPI_DSI_TX0_N
DSI_TX0_P	B9	MIPI_DSI_TX0_P
DSI_TX1_N	A10	MIPI_DSI_TX1_N
DSI_TX1_P	B10	MIPI_DSI_TX1_P
DSI_TX2_N	A12	MIPI_DSI_TX2_N
DSI_TX2_P	B12	MIPI_DSI_TX2_P
DSI_TX3_N	A13	MIPI_DSI_TX3_N
DSI_TX3_P	B13	MIPI_DSI_TX3_P
DSI_CLK_N	A11	MIPI_DSI_CLK_N
DSI_CLK_P	B11	MIPI_DSI_CLK_P

HDMI connection diagram

DSI/HDMI Bridge

Part number: LT8912B

ETHERNET‎

The device is equipped with a RJ45 connector placed on the side of the device. Diode on the front panel signals ETHERNET's operation.

RJ45 connector location

Ethernet connection diagram

GSM

The device is equipped with SIM7600E module connected with miniPCIE connector. Features:

• operation of protocols: CP, UDP, PPP, HTTP, FTP, MQTT, SMS, Mail
• GNSS (GPS, GLONASS, BeiDou) positioning
• microSIM card can be installed
• the device can be expanded with an antenna
• LED diode on the front panel signals GSM operation

MicroSIM connector

Function	Processor pin	Default function
USB power switch control	F23	USB2_VBUS
USB data differential pair negative	A23	USB2_D_N
USB data differential pair positive	B23	USB2_D_P

GSM connection diagram

USB HUB

Part number: USB2533

Wi-Fi‎ / Bluetooth

The device is equipped with a Wi-Fi module and can be expanded with a Wi-Fi antenna which takes place of digital inputs no. 1 & 2. The module is dual-band and operates on the frequencies of 2.4 and 5 GHz in 802.11.ac/a/b/g/n standard.

Wi-Fi connections diagram

UART 2

Device name: /dev/ttymxc1

Wi-Fi module

Part number: Sterling-LWB5

Digital inputs

The device is equipped with a 5 pin digital inputs (DI) connector with a maximum voltage of 30 V and a dry contact. Input signals connect directly to the CPU. 

DI location on the connector

DO connector pin	Processor pin	User space name
D1	AB15	gpiochip2 19
D2	AD18	gpiochip2 21
D3	AD13	gpiochip2 23
D4	AC14	gpiochip2 22
D5	AC15	gpiochip2 20

DI circuit block schematic

Where:

• R1 - pushup resistor

Digital inputs/outputs

The device is equipped with 7 digital input/output (DIO) connectors. They can operate as:

• binary input with a maximum voltage 30 V and a dry contact
  
• binary Vin output with maximum current 200 mA

DIO location on the connector

DIO connector pin	Input		Output
	User space name	Expander E pin	User space name	Expander A pin
H1	gpiochip5 9	26	gpiochip8 1	1
H2	gpiochip5 10	27	gpiochip8 2	2
H3	gpiochip5 11	28	gpiochip8 3	3
H4	gpiochip5 12	1	gpiochip8 4	4
H5	gpiochip5 13	2	gpiochip8 5	5
H6	gpiochip5 14	3	gpiochip8 6	6
H7	gpiochip5 15	4	gpiochip8 7	7

DIO circuit block schematic

Where:

• F1 - 200 mA fuse
• R1 - pullup resistor 4k7 Ω

Expander E

Inputs of the circuit are connected to the expander E via I2C4 interface.

Expander A

Outputs of the circuit are connected to the expander A via SPI1 interface.

Universal inputs/outputs

The device is equipped with 4 universal analog-digital inputs/outputs (UIO). They can operate as:

• DC voltage inputs for voltage in range of 0-10 V with input resistance of 100 kΩ
• current inputs for current in range of 0-4-20 mA with input resistance of 200 Ω
• current outputs with range of 4-20 mA
• temperature inputs of sensors: Pt1000, Ni1000, KTY, NTC
• resistance inputs with range of 0-5000 Ω
• dry contact inputs
• analog to digital converters with 24-bit resolution
• digital to analog converters with 12-bit resolution

Voltage is measured using a two channel analog to digital converter with 24-bit resolution. 

Current value can be set using a 4-channel digital to analog converter.

UIO location on the connector

Diagram of UIO circuit

Where:

• R1 - 200 Ω/1% measurement resistor
• R2 - 100 kΩ/1% measurement resistor
• R3 - changeable resistor for changing range of current sources; it can be: 649 Ω/1% or 1,649 Ω/1%

User space access

Analog-Digital Converter A Device name: /sys/bus/iio/devices/iio:device0

Analog-Digital Converter B Device name: /sys/bus/iio/devices/iio:device1

Digital-Analog Converter A Device name: /sys/bus/iio/devices/iio:device2

Possible configurations

Switching to particular modes of the circuit is realized by “Set Voltage Input”, “Set Current Input”, “Current Enable”, “Set R3 Resistance Value” and “Set Current Value” signals.

Configuration signal	Modes of operation
	DI dry contact	AI 0-10 V	AI 0-4-20 mA	AO 4-20mA / temperature* / resistance
Set Voltage Input	0	1	0	0
Set Current Input	0	1	0	1
Current Enable	1	0	0	1
Set R3 Resistance value	1	X	X	1 or 0**
Set Current Value	12-bit value***	X	X	12-bit value***

* by measuring resistance

** 1 for 1,649 kΩ/1% or 0 for 649 Ω/1% resistor

*** depends on the sensor (see examples for more)

Where:

• X - any value
• DI - digital input
• AI - analog input
• AO - analog output

UIO connector pin	Configuration signal	Expander pin
U1	Current enable	20
	Set voltage input	19
	Set current input	27
	Set R3 resistance value	21
U2	Current enable	3
	Set voltage input	22
	Set current input	28
	Set R3 resistance value	4
U3	Current enable	23
	Set voltage input	17
	Set current input	1
	Set R3 resistance value	18
U4	Current enable	26
	Set voltage input	24
	Set current input	2
	Set R3 resistance value	25

Expander C

Inputs of the circuit are connected to the expander C via I2C4 interface.