Hi,

 

I am using Nanopi Neo board and I need RS485 driver to control DE pin automatically.

I have prepared DTS Overlay file:

 

/dts-v1/;
/plugin/;

/ {
    compatible = "allwinner,sun8i-h3";

    fragment@0 {
        target = <&uart1>;
        __overlay__ {
            status = "okay";
            pinctrl-names = "default";
            pinctrl-0 = <&uart1_pins &uart1_de_pin>;
            rs485-rts-gpios = <&gpio6 8 0>;  /* PG8 active-low */
            linux,rs485-enabled-at-boot-time;
            rs485-rts-delay = <0 300>;
        };
    };

    fragment@1 {
        target = <&uart2>;
        __overlay__ {
            status = "okay";
            pinctrl-names = "default";
            pinctrl-0 = <&uart2_pins &uart2_de_pin>;
            rs485-rts-gpios = <&gpio0 2 0>;  /* PA2 active-low */
            linux,rs485-enabled-at-boot-time;
            rs485-rts-delay = <0 300>;
        };
    };
};
 

I produced dtbo file from dts one with the command: dtc -@ -I dts -O dtb -o rs485.dtbo rs485.dts

 

I copied this rs485.dtbo file to /boot/dtb/overlay. Also I added rs485 string to ArmbianEnv.txt and rebooted. 

But only TX works, RX doesn't. 

 

What should  I do else to make it work?

Edited September 2, 20251 yr by ABK

spendist is the maintainer of the Nanopi Neo.  Maybe he has something to say.

 

Did you try another kernel?  Another OS?