Am Wed, 21 Mar 2012 22:56:55 +0100
schrieb Tim Schneider <schneid5@xxxxxxxxxxxxxx>:
> Interestingly I did find a workaround that seems to always work:
> I am now sending my command byte per byte and always pausing for a second in
> between each write. So far I was successful with this workaround even though
> it's really not a pretty solution :( Could it have something todo with the
> (low) baudrate of only 9600 of the chip?
Do you check how many bytes were written? You might need do resend parts of your
message like:
do
if((ret = ftdi_write_data(&ftdic, (unsigned char *)buf +i, bytes-i )) >= 0)
i+= ret;
else
break;
while(i < bytes);
Sometimes playing with the latencytimer or the read/write chunksize also gives
good results, but not always.
>
> Am 21.03.2012 um 10:28 schrieb Matthias Janke:
>
> > Hi Tim,
> >
> > Am Wed, 21 Mar 2012 09:24:52 +0100
> > schrieb Thomas Jarosch <thomas.jarosch@xxxxxxxxxxxxx>:
> >>> My device periodically sends sensor data across the usb interface once it
> >>> received the start command, which is just the word "start" send in ascii
> >>> letters to the device. Unfortunately the sending of the start command
> >>> somehow fails.
> >>
> >> We had trouble back in the days with the first write command
> >> getting lost. When we tried to track it down, the problem vanished.
> >
> > I had this problem where the first byte of the first write got lost only
> > with
> > the 0.x branch. I'm now using the 1.x branch and never lost any byte in
> > sending or reading, even though it takes usually more than one read to get
> > all bytes of a transmission.
> >
> > Cheers,
> > Matthias
> >
> >
> >
> > --
> > libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
> > To unsubscribe send a mail to libftdi+unsubscribe@xxxxxxxxxxxxxxxxxxxxxxx
> >
>
>
> --
> libftdi - see http://www.intra2net.com/en/developer/libftdi for details.
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--
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Dipl.-Phys. Matthias Janke
Physikalisches Institut der Universität Heidelberg
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