libftdi Archives

Subject: Re: Rare errors in data transmission with FT2232H

From: Jim Paris <jim@xxxxxxxx>
To: libftdi@xxxxxxxxxxxxxxxxxxxxxxx
Date: Fri, 5 Apr 2013 13:27:27 -0400
It seems strange that both libftdi and the kernel driver would have
the same problem.  Maybe try plugging in the device and going through
the Linux driver without running any libftdi code first, just in case
libftdi itself is configuring the device in a way that causes
problems.

-jim

Vojtech Michalek wrote:
> In order to try to get additional information on the errors origin, I
> decided to replace libftdi programs with an alternative ones using
> proprietary ftd2xx library. I did not expect any significant change, but it
> has transferred more than 4GB without any error so far.
> 
> Vojta
> 
> 
> On Thu, Apr 4, 2013 at 5:26 PM, Vojtech Michalek <vojtechuv@xxxxxxxxx>wrote:
> 
> > Hi all,
> >
> > during my measurements, I encounter rare errors in data stream (i.e.,
> > approx 10 errors in 1GB data). I use FT2232H in standard asynchronous
> > serial mode at 3MBd, transmitting approx. 300kBps. I try to debug it while
> > sending incrementing 16bit number in a loop, so that I could check what
> > happens with data. From time to time a data block of various size is
> > missing.
> >
> > The same behaviour is reproducible with two topologies:
> > 1) transmitter: LPC1343 microcontroller, receiver: FT2232H
> > 2) transmitter: FT2232H, receiver: another FT2232H
> >
> >  In order to exclude I do something wrong with libftdi, I try to read the
> > data from FT2232 with linux command "cat" (and write with system command
> > write for the second topology). I got similar error rate as with libftdi
> > functions but with an additional strange effect. Two zero bytes are stuffed
> > in the data stream with the following "structure": single zero byte, after
> > next correct 511 bytes comes second zero byte, and after next correct 3587
> > bytes (really strange number to me) is the missing block of data. Then
> > several hundreds of MB of correct data follows before next error occurs.
> >
> > Have you any hint what I could try to make the communication more reliable?
> >
> > Thanks,
> > Vojta
> >
> 
> 
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