UART
Introduction
AIO-3588JD4 has one RS232 interfaces and one RS485 interface
The serial interface diagram of the AIO-3588JD4 development board is as follows:
DTS configuration
The RS232 interface of the development board is extended by the main control UART1, and the RS485 interface is extended by the main control UART6.
File path kernel/arch/arm64/boot/dts/rockchip/aio-3588jd4.dtsi
/* RS485 */
&uart6{
pinctrl-0 = <&uart6m1_xfer>;
status = "okay";
};
/* RS232 */
&uart1{
pinctrl-0 = <&uart1m1_xfer>;
status = "okay";
};
After configuring the serial port, the nodes on the software corresponding to the hardware interface are:
RS232: /dev/ttyS1
RS485： /dev/ttyS6Send and receive verification
Users can use different host's USB-to-serial adapters to send and receive data to the serial port of the development board according to different interfaces. For example, the debugging steps of RS485 are as follows(AIO-3588JD4 RS485 is half-duplex and requires gpio to control transmission and reception):
(1) Development board sends, host receives
# The host terminal executes first:
# /dev/ttyUSB0 is the node of the host serial adapter, modify it according to the actual situation
cat /dev/ttyUSB0
# The development board debugs the serial port terminal and executes:
# /dev/ttyS1 is the RS485 node
echo "firefly RS485 test..." > /dev/ttyS1The host terminal will receive the string "firefly RS485 test..."
(2) Host sends, development board receives
echo 34 > /sys/class/gpio/export
echo out > /sys/class/gpio/gpio34/direction
# To debug the serial terminal on the development board, execute first:
# /dev/ttyS1 is the RS485 node
echo 0 > /sys/class/gpio/gpio34/value
busybox stty -echo -F /dev/ttyS1 # turn off echo
cat /dev/ttyS1
# The host terminal executes:
# /dev/ttyUSB0 is the node of the host serial adapter, modify it according to the actual situation
echo 1 > /sys/class/gpio/gpio34/value
echo "firefly RS485 test..." > /dev/ttyUSB0The development board debugs the serial terminal to receive the string "firefly RS485 test..."