UART

Hardware

The serial port 5 interface diagram of the ROC-RK3506B-CC hardware
version is as follows:


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";
   };

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

   UART5:   /dev/ttyS5

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..."