Leigh Gawne escreveu:
>I am working on an application to which I need to interface to the MDB
>(Multiple-Drop Bus) which is a bus standard used in vending machine
>applications. The MDB protocol uses a start bit, 9 data bits and a stop bit.
>I am looking at using the interrupt error code (I will obviously lose the
>capability to determine framing errors, etc) and sticky parity capability of
>the PX2xx's UART to interface with the MDB protocol and control the parity
>bit on Tx accordingly.
>Does anyone happen to know how the PX2xx's UART behaves on detection of a
>parity error in terms of whether or not it still loads the FIFO with the
>erroneous data? I can use the encoded interrupt source to determine the
>parity bit value, but obviously need the data to go along with it (the MDB
>bus is spec'd to run at 9600 baud so as long as I service the interrupt fast
>enough such that the FIFO is only allowed to fill to a single byte, it
>should not be a problem).
>Thanks for any help in advance.
AFAIK, you can use the NSSP serial port in order to capture the
bitstream at more flexible formats. I suspect you would need to do the
parity checking yourself as well, but at least that way you wouldn't
need to hack the UARTs.
I never tried it myself, so I can't give you any more specific hints.
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