imx uart RS485 rx not working

[chenwei45]

Hi,

I'm working on the RS485, but the rx always couldnot work.

Hardware: imx6qsabresd

The dts is as:

&uart2 {
|   pinctrl-names = "default";
|   pinctrl-0=<&pinctrl_uart2>;
|   uart-has-rtscts;
|   linux,rs485-enabled-at-boot-time;
|   status = "okay";
};

|   |   pinctrl_uart2: uart2grp {
|   |   |   fsl,pins = <
|   |   |   |   MX6QDL_PAD_EIM_D26__UART2_TX_DATA|  0x1b0b1
|   |   |   |   MX6QDL_PAD_EIM_D27__UART2_RX_DATA|  0x1b0b1
|   |   |   |   MX6QDL_PAD_EIM_D28__UART2_CTS_B||   0x1b0b1
|   |   |   >;
|   |   };

I configure the rs485 flag as:

    struct serial_rs485 rs485conf;
    if (ioctl (pf, TIOCGRS485, &rs485conf) < 0) {
        printf("Error reading ioctl port");
    }

rs485conf.flags |= SER_RS485_ENABLED;

ioctl (pf, TIOCSRS485, &rs485conf);

When I use microcom to debug(I add a print at rts active/inactive), it could send out data but couldnot receive.

root@imx6qsabresd:~# microcom -s 115200 /dev/ttymxc1
imx-uart 21e8000.serial: imx_set_termios !!!!!
imx-uart 21e8000.serial: imx port rts active
imx-uart 21e8000.serial: imx_set_termios !!!!!
imx-uart 21e8000.serial: imx port rts active
imx-uart 21e8000.serial: imx rts inactive

Could you give a hand?

Thanks & Regards,

Wei

[igorpadykov]

Hi Wei

one can check if dte or dce mode used, please check

Table 86. UART I/O Configuration vs. Mode i.MX6DQ Datasheet

http://www.nxp.com/docs/en/data-sheet/IMX6DQCEC.pdf

and check signal on i.mx uart rx pad with oscilloscope.

Also may be useful to check i.mx uart module register settings with jtag.

Best regards
igor
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[chenwei45]

Many thanks for your help. The issue was resolved for the connector we use is not for 485 but 232. :smileysad: