RS485 Rx fail due the echo from Colibri module

[viktorasd]

Hello,
Sending data from the Colibri to the RS485 line works well. But Rx fail because Colibri UART driver starts send the echo. Please, look at the oscilloscope diagram.
How to disable echo from the Colibri?

Device tree:

&uart4 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart4>;
	assigned-clocks = <&clks IMX7D_UART4_ROOT_SRC>;
	assigned-clock-parents = <&clks IMX7D_OSC_24M_CLK>;
	/*cts-gpios = <&gpio5 16 GPIO_ACTIVE_HIGH>;*/
	rts-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;
	fsl,dte-mode;
	linux,rs485-enabled-at-boot-time;
	status = "okay";
};

[viktorasd]

I’ve changed uart4 to pure rs232 and get the echo also. It’s sent by definitely by driver because it has delayed by the char.

Device tree:

        pinctrl_uart4: uart4-grp {
        		fsl,pins = <
        			MX7D_PAD_SAI2_TX_SYNC__UART4_DTE_TX 0x79 // SODIMM 27
        			MX7D_PAD_SAI2_TX_BCLK__UART4_DTE_RX 0x79 // SODIMM 25
        		>;
        };

 
    &uart4 {
    	pinctrl-names = "default";
    	pinctrl-0 = <&pinctrl_uart4>;
    	assigned-clocks = <&clks IMX7D_UART4_ROOT_SRC>;
    	assigned-clock-parents = <&clks IMX7D_OSC_24M_CLK>;
    	fsl,dte-mode;
    	status = "okay";
    };

[viktorasd]

I’ve changed uart4 to pure RS232. And get echo also from the Colibri. It definitely sent by driver because it delayed by char.

Device tree:

	pinctrl_uart4: uart4-grp {
		fsl,pins = <
			MX7D_PAD_SAI2_TX_SYNC__UART4_DTE_TX 0x79 // SODIMM 27
			MX7D_PAD_SAI2_TX_BCLK__UART4_DTE_RX 0x79 // SODIMM 25
		>;
	};

&uart4 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart4>;
	assigned-clocks = <&clks IMX7D_UART4_ROOT_SRC>;
	assigned-clock-parents = <&clks IMX7D_OSC_24M_CLK>;
	fsl,dte-mode;
	status = "okay";
};

[max.tx]

Hi

You could try from the command line:

stty -F /dev/ttymxcX -echo

If you are accessing the serial port as part of a program then termios is the keyword to setup the port. E.g. here is a example which disables echo on the stdin.

Max