&uart3 {
        pinctrl-names = "default", "sleep";
        pinctrl-0 = <&uart3_pins_a>;
        pinctrl-1 = <&uart3_pins_b>;
        status = "okay";

        sunxi,uart-rs485 = <1>;
        sunxi,uart-485fl = <0>;
        sunxi,uart-485oe-gpios = <&pio PE 10 GPIO_ACTIVE_HIGH>;
};

&uart5 {
        pinctrl-names = "default", "sleep";
        pinctrl-0 = <&uart5_pins_a>;
        pinctrl-1 = <&uart5_pins_b>;
        status = "okay";

        sunxi,uart-rs485 = <1>;
        sunxi,uart-485fl = <0>;
        sunxi,uart-485oe-gpios = <&pio PE 11 GPIO_ACTIVE_HIGH>;
};

sunxi,uart-rs485 是否开启rs485
sunxi,uart-485fl 485 DR线极性
sunxi,uart-485oe-gpios 485 DR线IO口
配置完成后修改menuconfig，打开minicom，编译，烧录
输入minicom -s，选择设备树中配置的串口，务必关闭硬件流控


修改完选择Save setup as dfl，然后Exit，修改完成，此时可实现自收发，方向线由驱动层自动控制