Idle state of RTS in RS-485 mode on IMX6

jeff_hunsinger — Mon, 04 Dec 2017 20:24:55 GMT

I activated RS-485 mode on the IMX6UL using UART7 and the RTS pin transitions as expected when I have the port open. However, when I close the port, the pin goes high even though I have it configured to be low when not transmitting. There is an external pull-up on this pin because it is used to configure the IMX6UL at reset.

Is there a way to have the pin drive low by default when the UART is not open?

I am using the LCD_DATA06_DTE_RTS pin with the UART in DCE mode.

I use the following to enable RS-485 mode in the Linux driver:

rs485conf.flags |= SER_RS485_ENABLED;
rs485conf.flags |= (SER_RS485_RTS_ON_SEND);
rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);

ioctl(fd, TIOCSRS485, &rs485conf);

Thank you,

Jeff

Re: Idle state of RTS in RS-485 mode on IMX6

igorpadykov — Mon, 04 Dec 2017 23:16:38 GMT

Hi Jeff

one can try to change behavior adding codes in driver configuring

that pad as gpio, with low state by default when the UART is not open.

Best regards
igor
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i.MX ProcessorsのトピックIdle state of RTS in RS-485 mode on IMX6

Idle state of RTS in RS-485 mode on IMX6

Re: Idle state of RTS in RS-485 mode on IMX6