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9. UART

9.1. Hardware​

The serial port 5 interface diagram of the ROC-RK3506J-CC hardware version is as follows:

_images/usage_uart_interface.jpg

9.2. DTS Configuration​

UART5 is not enabled by default. Add the following content to the end of the file path kernel/arch/arm/boot/dts/rk3506b-firefly-roc-rk3506b-cc.dtsi and compile the kernel and burn it to the board:

/* uart5 */
&uart5 {
	pinctrl-0 = <&uart5m1_xfer_pins &uart5m1_ctsn_pins &uart5m1_rtsn_pins>;
	status = "okay";
&#125;;

After configuring the serial port, the hardware interface corresponds to the node on the software:

UART5:   /dev/ttyS5

9.3. UART send and receive verification​

The easiest way is to short the UART5 TX RX pins, and then use the command to execute the command in the debug serial port or ADB

busybox  stty -echo -F /dev/ttyS5         # Disable echo
cat /dev/ttyS5 &                          # Get /dev/ttyS5 input string in the background
echo "firefly uart test..." > /dev/ttyS5  # Input string

Finally, the debugging serial terminal can receive the string “firefly uart test…”