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several question about 6748's UPP peripheral.

twicave Feng
Intellectual 850 points

Q1. when work at recv mode. It's up to DMA auto switch "Wait" signal or should be done by user?

Q2.I tryed to recv multi-line data from UPP, but only first line data is recved, 

      I didn't enable interrupt of UPP, but using polling mode.

      I can observed the DMA "End of Line Event " is triggered. but nothing else.

      Is there anything i missed?

  • 0
    TI__Expert 8890 points

    During normal operation in receive mode, the uPP peripheral will never assert WAIT.  The WAIT signal is an important part of the uPP protocol, but the uPP peripheral does not actually use it in receive mode.  There is also no way for the user to manually activate the WAIT signal.  In transmit mode, uPP will definitely honor the WAIT signal if an external receiver asserts it.

    When handling the end of line (EOL) interrupt, it's possible the "mask" multiple interrupts and only enter the ISR one time.  This becomes more likely the shorter the lines are.  For example, a line of 128 bytes at maximum uPP clock speed (75 MHz) will only take around 0.853 microseconds to complete in 16-bit mode.  If you want to handle individual EOL interrupts, you may want to increase your line size to give your ISR more time to work with.  The uPP user guide includes some tips to create a robust uPP ISR that will miss fewer "masked" uPP interrupts.

    Hope this helps.

  • 0 in reply to Joe Coombs
    Intellectual 850 points

    thanks for your reply, joe