From: Leigh G. <le...@or...> - 2006-11-15 18:47:09
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Hi Tim, You can find a version of the MDB spec here: http://www.coinmax.pl/produkty/mdb.pdf The protocol is based on a Master-Slave relationship, with a single bus master initiating communication with all bus slaves. Whilst the physical layer could potentially support full duplex operation (master Rx and Tx signals), it appears the protocol itself operates in half duplex with a series of specified maximum timeouts in between commands and responses. Leigh ps. I have started a new thread for this response so as not to confuse "thread aware" mail clients as I was informed yesterday! (I appended this post to a previous email thread) -----Original Message----- From: gum...@li... [mailto:gum...@li...]On Behalf Of tim...@co... Sent: 15 November 2006 17:56 To: General mailing list for gumstix users. Subject: Re: [Gumstix-users] PXA2xx UART parity bit Hi Leigh, Is the MDB spec available to the public? 9 data bits? I think the 8051 can to this. What you are suggesting might work, but ... The problem I see is in full duplex operation. -------------- Original message ---------------------- From: "Leigh Gawne" <le...@or...> > Hello all, > > 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. > > Leigh > > > ------------------------------------------------------------------------- > Take Surveys. Earn Cash. Influence the Future of IT > Join SourceForge.net's Techsay panel and you'll get the chance to share your > opinions on IT & business topics through brief surveys - and earn cash > http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV > _______________________________________________ > gumstix-users mailing list > gum...@li... > https://lists.sourceforge.net/lists/listinfo/gumstix-users ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ gumstix-users mailing list gum...@li... https://lists.sourceforge.net/lists/listinfo/gumstix-users |