2014-05-09 7:28 GMT+03:00 Ryan Tennill <[email protected]>: > I can't comment on the DMX issue but here's a handy page for the flow > control signals: > > http://www.ftdichip.com/Support/Knowledgebase/index.html?an232b_04flowctl.htm > > RTS/CTS and DTR/DSR are harware signals where as XON/XOFF usually fall > under 'software' flow control. I have only used RTS/CTS on the FT23R to > date. I don't know if there's a particular reason to use DTR/DSR vs RTS/CTS > unless you're interfacing with some legacy hardware that uses it. > Thanks, that was very useful! I am communicating using EIA-485 as physical layer but DMX-512A has no concept of flowcontrol so setting it to off and RTS to off seems to be the correct thing.
I started looking at the stream reading example figuring that maybe that way I'd do the Break/MAB detection on the host but it seems the FT4232HQ doesn't support synchronous FIFO mode.... Either way the break/MAB do seem to be detected properly since as far as I can tell they don't add data (gibberish) to the captured data, it's just that I lack a way of reading instantly the moment a break is reached (and consequentially a whole packet is in the buffer). Thanks so far, Eli > > Ryan > > > On 5/8/2014 5:29 PM, E.S. Rosenberg wrote: > > > 2014-05-09 1:27 GMT+03:00 E.S. Rosenberg < > [email protected]>: > >> Hi all, >> >> Several years ago Rui Barreiros already posted a question on the subject >> which at the time doesn't seem to have been resolved and I am running into >> the same problem more or less: >> >> The DMX packet is read but ends up shifted over different amounts of >> bit every read. >> >> I currently suspect that this is all dependent on when the OS issues >> the ftdi_read_data() call, I suspect this because when I ran my test >> program using gdb the shifts were a lot more extreme (almost 0.5 packet) >> then when it was running directly. >> >> The packet itself is basically: >> 1. BREAK (>= 88us of LOW) >> 2. MAB (>= 8us HIGH) >> 3. 25-513 data slots (1b start HIGH, 8b data, 2b STOP HIGH each) >> >> So my question is: Is there any way to 'allign' the reads to the >> break+mab? >> >> attached is my modified version of the serial_test.c example. >> >> Side questions: >> - Can someone on the list explain the different flow control options? >> - What is the RTS? >> >> Thanks, >> Eliyahu - אליהו >> > > I meant to also add a link to the other thread: > http://developer.intra2net.com/mailarchive/html/libftdi/2012/msg00171.html > > The device I am using is a USB-COM485-Plus4 > > Thanks, > Eli > > ------------------------------ > > *libftdi* - see http://www.intra2net.com/en/developer/libftdi for details. > To unsubscribe send a mail to [email protected] > > > > ------------------------------ > > *libftdi* - see http://www.intra2net.com/en/developer/libftdi for details. > To unsubscribe send a mail to [email protected] > > -- libftdi - see http://www.intra2net.com/en/developer/libftdi for details. To unsubscribe send a mail to [email protected]
