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TL16C752D: TL16C752D & RXRDYA,B and error stop bit.

Victor Nedvedskij
Prodigy 20 points
Part Number: TL16C752D

Hello.

Why doesn't RXRDYA,B go low when a character error occurs with an invalid stop bit?

In the TL16C752B, this works.

Victor.

  • 0
    TI__Genius 15345 points

    Hi Victor,

    Could you provide scope shots of the problem and explain how to recreate it? You can post them to this thread or you can email them to me at c-ayoub@ti.com .

    Correct me if I am misunderstanding the issue, but RXRDY goes active (LOW) when the trigger level has been reached or when a timeout interrupt occurs. It goes inactive (HIGH) when the FIFO is empty or an error in the RX FIFO is flagged by LSR[7]. LSR[7] is set when there is an error anywhere in the RX FIFO so I would expect RXRDY to go high. This is true for both devices.

    All this information can be found on page 22 and 26 of the datasheet..

    Best,

    Chris

  • 0
    Prodigy 20 points
    Hello.

    Your explanations are absolutely correct if the received character
    has the correct format. But if the received character has a stop bit error (LSR=0xF9), then RXRDYA_B pin does not go low. (I track the pin with an oscilloscope).
    If the format is correct then RXRDY pin switches perfectly.
    But RXRDY go low in TL16C752B device, with and without error.



    Victor.
  • 0 in reply to Victor Nedvedskij
    TI__Genius 15345 points

    Since this is being handled over offline I am going to close the thread.

    Best,

    Chris