Thread: TxD line high

  1. #1
    Registered User
    Join Date
    Feb 2003

    TxD line high

    Hello All,

    I have an Serial port application, where I need to make TXd line stay high for specified amount of time. Wanted to know, how do I do this? This will be done after configuring the UART port.

    Please let me know...

  2. #2
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    You'll need to say which OS and Compiler you have
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.

  3. #3
    Registered User
    Join Date
    Feb 2003
    No OS, it is firmware. Processor is 8051

  4. #4
    Registered User
    Join Date
    Jul 2004
    Well, not knowing the device you're using in particular, I'll just
    point out one fact about most UARTS: the TxD line is tied to a
    shift register that's loaded when the next byte is to be transmitted.
    If you wanted all 1's for 8 bit times, you could do it by transmitting
    a 1 (IIRC); you'd get 8 high bit times. You'll have start/stop and parity bit issues possibly. IIRC RS-232 transmits a negative voltage for
    a space (0 bit) and a positive voltage for a mark (1 bit), but I get
    them confused sometimes

    If it's not a generic UART maybe it has a specific way of toggling the


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