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Piccolo 28035 LIN in SCI FIFO mode

StephanS
Genius 4087 points

Hi all,

I would like to use the LIN module as second SCI interface and have some questions:

- The 20kHz baudrate limit seems to be valid only for LIN mode. In SCI mode, I can go up to 1MBaud - at least on my ezDSP. Is that correct or out of spec?

- How can I work with the buffers in SCI mode?
I would like to know the fifo level of the receive buffers when/before reading them. Is this possible?
I would like to poll the receive buffers and read them before they overflow.
Is there some combination of RXRDY and SCIFORMAT.LENGTH to get the fifo level?

Thanks!

  • 0
    Genius 4087 points

    Hmm, nobody sems to use LIN in SCI buffered mode....

    My observations so far are that LIN SCI mode is okay for slower baudrates and non-buffered mode.
    Since the LIN uses buffers and not FIFO as the SCI, you can never be sure to read out all received bytes (what if a byte is received while reading out?).

    So I think LIN is no fully functional second SCI on the 28035 - at least not as FIFO replacement.

  • 0 in reply to StephanS
    TI__Guru* 87155 points

    Stephan,

     

    Max baud rate you can achieve on LIN SCI in F28035 is 0.9375Mbps.

     

    When BLIN is in SCI mode and multi-buffer mode is selected, based on the configured SCIFORMAT.LENGTH value, RXRDY flag will get set at the end of the reception of (SCIFORMAT.LENGTH value + 1) frames.

     

    There is no user readable counter register which displays the current state of the buffers.

    Software is expected to wait until RXRDY flag is set and then check the RDx registers for received data.

     

    Regards,

    Vamsi

     

     

  • 0 in reply to Vamsi Gudivada
    Genius 4087 points

    Vamsi,

    Thanks for the confirmation and clarification.

    I will use LIN-SCI only in non-buffered mode, though.