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Problem with UART RTS/CTS Signals

Discussion in 'Electronic Design' started by KKL, Jul 4, 2007.

  1. KKL

    KKL Guest

    Hi,

    I am developing a Interrupt driven UART driver for Coldfire 5208 and
    have problems with the flow control.

    I have configured the UMR1[RXRTS] so that the my RTS goes
    automatically inactive when there is FIFO condition and becomes
    automatically active again when a postion in FIFO becomes active
    again. I did this because my UART driver receives the packets
    correctly with slower polling rate for Modbus RTU communication (my
    device act as Master) but with faster polling rate I get FIFO overrun.

    I have configured the multiplexed pins to work for UART signals (TXD,
    RXD, RTS & CTS) for UART0. As per the receiver functional diagram in
    5208 reference manula the RTS signal should be manually made active
    the first time and then the function of this signal should be
    automatic.

    My problem is my RTS signal never goes active at the first place and
    the other (trasmitting) device never gets the CTS signal (even when I
    manually make it active (once before I open my UART channer for
    receiving) by making UOP1[RTS]=1 )

    Have you faced similar problem?

    I am also confused which are the valid configurations from the below
    combinations

    UMR1[RXRTS] = 1 UMR2[TXCTS]=1 (Tested with this also)
    UMR1[RXRTS] = 1 UMR2[TXCTS]=0 UMR2[TXRTS]=0 (I am currently using this
    one)
    UMR1[RXRTS] = 0 UMR2[TXCTS]=1 UMR2[TXRTS]=1
    UMR1[RXRTS] = 0 UMR2[TXCTS]=1 UMR2[TXRTS]=0

    Can anyone suggest the possible causes for such problem?
     
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