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UART RTS_pin manually control problem?

Keldy
Expert 1835 points

Hi,

i want to control uart rts pin manually, set high and low by my program.

I'm using uart1 AM335x. in my program:

UART1_RTS_PINMUX = MODE4;

while(1)

{

(UART1_BaseAddr + UART_MCR) |= (1 << 1);        //clear rts

delay_1s();             //delay 1 second

(UART1_BaseAddr + UART_MCR) &= ~(1 << 1);    //set rts

delay_1s();            //delay 1 second

}

when i measure the UART1 RTS pin, it keep pulling low, 0V.

how i can control the UART RTS pin manually by code?

do i miss-configure something in my program?

Thanks and Regards

Keldy

  • 0
    TI__Intellectual 2725 points

    Need few infor before suggesting.

    1. Which Board?

    2. Is the pin-mux properly set for this pin

    3. Is Total number of available pins are short in case of AM335x, Pins are mux'ed between different modules and are available only in depending on few criteria (like Profile in case of EVM, ON daughter board in case of BeagleBone ...)

    Regards

    Gururaja

  • 0 in reply to Gururaja Hebbar
    TI__Intellectual 2725 points

    I forgot to mention. On EVM, UART1 pins are not available on DB9 connector. They are used by Bluetooth Module

  • 0 in reply to Gururaja Hebbar
    Expert 1835 points

    Hi,

    i use my custom board. The UART1 tx, rx, cts, rts, are connected to RS232 transceiver, and to DB9 connector. I'm using PSP04.06.00.07, you mention about bluetooth module, do i need to disable the bluetooth module before using UART ?

    Actually i want to use Full Modem of RS232, i need include hardware flow control and software flow control in my design. But seem like linux serial driver not supported, that why i need to manually trigger the control line of RS232.

    UART1: tx, rx , cts, rts pin mux select is mode 0

    UART1: ri, dcd , dsr, dtr pin mux select is mode 4

    is there any better idea rather than trigger the line manually?

    Thanks and Regards

    Keldy

  • 0 in reply to Keldy
    TI__Intellectual 2725 points

    1. in 07 release code, Bluetooth module uses uart1 port. Disable Bluetooth init function from board-am335x.c (mmc2_wl12xx_init, uart1_wl12xx_init & wl12xx_init)

    2. Linux supports UART flow control. use stty command to enable hw flow control.

  • 0 in reply to Gururaja Hebbar
    Expert 1835 points

    Hi,

    i use command "stty -F /dev/ttyO1 crtscts" to enable RTS/CTS hardware flow control, UART1 still can sending out data athough the CTS line not asserted by a RS232 device, no matter what hardware flow control setting i use on the RS232 device, let say DTR/DSR flow control, the UART1 still transmit data sucessfully. seem like UART1 dont care the RTS, CTS, DTR, DSR lines.

    Plus, do linux have prepare an option to enable DTR/DSR flow control by command stty?

    some linux forum said linux not support DTR/DSR flow control, is it true?

    after i go through the AM335x TRM, there is no configuration for DTR/DSR, only have RTS/CTS and Ixon/ixoff flow control.

    Thanks and Regards

    Keldy

  • 0 in reply to Keldy
    Intellectual 390 points

    Keldy,

     

    We are experiencing the very same problem.

    Custom board w/ Beaglebone as guide. Added standard, non-bluetooth UART1 pinmux to kernel init. Set app code and minicom terminal with hardware flow control and communication is fine, but no evidence of activity with a scope on the RTS/CTS lines. The other processor in or system needs hardware flow control lines to be active.

    Have you received any info or did you find a solution?

     

    Dave