Hardware Function Usage

Debug Serial Port

The debug serial port of the IHC-3308GW is UART4. The serial port parameters are: baud rate 1500000, 8 data bits, 1 stop bit, no parity, no flow control.

The debug serial port is a TTL-level interface. An external USB to TTL serial module is required for debugging.

For the connection and usage of the debug serial port, please refer to: Debug Serial Port.

UART (RS485 / RS232)

The expansion board expands multiple serial ports, including 3 RS485 ports and 1 RS232 port.

The kernel supports the above serial port functions by default. The device files corresponding to each serial port are as follows:

RS485_1: /dev/ttysWK0
RS485_2: /dev/ttysWK1
RS485_3: /dev/ttysWK2
RS232  : /dev/ttysWK3

Take RS485_1 as an example:

• Connection

Connect the A and B pins of RS485_1 to the A and B pins of the host serial port adapter (USB to 485 serial module) respectively.

• Open the serial terminal of the host

Open kermit in the terminal and set the baud rate:

$ sudo kermit
C-Kermit> set line /dev/ttysWK0
C-Kermit> set speed 9600
C-Kermit> set flow-control none
C-Kermit> connect

/dev/ttyUSB0 is the device file of the USB to serial port adapter recognized by the host.

• Send data

Run the following command on the device:

echo "Firefly RS485 test..." > /dev/ttysWK0

The serial terminal of the host will receive the string "Firefly RS485 test...".

• Receive data

First run the following command on the device:

cat /dev/ttysWK0

Then enter the string "Firefly RS485 test..." in the serial terminal of the host, and the same string can be seen on the device side. The verification methods of RS232 (/dev/ttysWK3), RS485_2 and RS485_3 are the same.

CAN

• Connection

Just connect the CANH and CANL of the device to the CANH and CANL of the communication peer correspondingly.

• Send data

ip link set can0 down
ip link set can0 type can bitrate 250000
ip link set can0 up
cansend can0 123#1122334455667788

• Receive data

ip link set can0 down
ip link set can0 type can bitrate 250000
ip link set can0 up
candump can0

• Loopback mode test

ip link set can0 down
ip link set can0 type can bitrate 50000 loopback on
ip link set can0 up
candump can0 &
cansend can0 123#11223344556677

DIN

The IHC-3308GW supports an optocoupler-isolated interface, where DI corresponds to INPUT1 in the hardware schematic, and COM corresponds to INPUT_COM in the hardware schematic.

• Circuit schematic

• Detection

When INPUT1 and INPUT_COM are connected, GPIO_INPUT1 will detect a low level; when INPUT1 and INPUT_COM are disconnected, GPIO_INPUT1 will detect a high level.

The corresponding GPIO is as follows:

GPIO_INPUT1: GPIO1_A6, 38

The detection method is as follows:

# Apply for the GPIO
echo 38 > /sys/class/gpio/export
# Set it as input
echo in > /sys/class/gpio/gpio38/direction
# Read the level value
cat /sys/class/gpio/gpio38/value

DOUT

The IHC-3308GW supports a relay interface. DO corresponds to OUTPUT1 in the hardware schematic, and COM corresponds to RELAY_COM1 in the hardware schematic.

• Circuit schematic

• Control

When RELAY_CTL1 outputs a low level, OUTPUT1 and RELAY_COM1 are disconnected; when RELAY_CTL1 outputs a high level, OUTPUT1 and RELAY_COM1 are connected.

The corresponding GPIO is as follows:

RELAY_CTL1: GPIO1_B2, 42

The control method is as follows:

# Apply for the GPIO
echo 42 > /sys/class/gpio/export
# Set it as output
echo out > /sys/class/gpio/gpio42/direction
# Set the level value, 1 / 0
echo 1 > /sys/class/gpio/gpio42/value

LED

The IHC-3308GW supports 6 customizable LEDs, and the corresponding GPIOs are as follows:

The control method is as follows, taking L1 as an example:

# On
echo 1 > /sys/class/leds/firefly\:green\:L1/brightness
# Off
echo 0 > /sys/class/leds/firefly\:green\:L1/brightness