On Fri, Jun 05, 2015 at 03:12:01PM +0200, d.rodomonti wrote:
> Hi all,
>
> I am not able to understand where is the problem with the python sw
> that I wrote, so I decide to convert it in C++ using directly the
> d2xx library provided by FTDI and I have no more the problem
> discussed.
> The two code are quite the same excepted for the following action
> performed before each read action:
> ftStatus = FT_GetQueueStatus(ftHandle[0], &dwRxSize);
> :
> :
> ftStatus = FT_Read(ftHandle[0], pcBufRead, dwRxSize, &dwBytesRead);
That should just: "ask how many bytes are available" and then read
exactly that many bytes.
Just asking for "as many as you have", should also work.
On the other hand: I'm hearing these reports of dataloss so often that
I'm starting to believe that there is something going on.
It could be a design problem. Maybe libftdi cannot keep read-buffers
available for the ftdi to dump data into when it is not actively
running. So that your program would need to be in "ftdi_read" 99% of
the time to be able to catch 99% of the data. Not a desirable
situation.
Anyway, such low-level design issues are out of my league (in my free
time. I'll happily investigate to the bare metal if you're willing to
pay my commercial rate...).
Roger.
> maybe something similar is already performed with ftdi.read_data
> command, but this is the only difference that I found.
> Is it possible that I didn't install properly the library?
> Have you some explanation to this strange behavior?
>
> Thank you in advance for your support.
>
>
> On 03.06.2015 13:08, d.rodomonti wrote:
> >Thank you Roger for yours tips.
> >
> >The system is up and running, but the sw part is developed in
> >visual basic (and I don't like it).
> >My target is to write a light sw version in python following the
> >vb code as template, but probably I missed some parts.
> >
> >I let you know when I will understand the problem.
> >
> >On 03.06.2015 12:51, Rogier Wolff wrote:
> >>On Wed, Jun 03, 2015 at 12:45:38PM +0200, d.rodomonti wrote:
> >>>The data are provide to the 245 by a NIOS controller that implements
> >>>a sort of hand shake protocol.
> >>Sort of? Does it, or does it not check for the "RXNE" (or whatever it
> >>is called signal?
> >>
> >>Even if in tests is mostly works, you must account on that hardware
> >>side that the software migth decide to do something else for a while,
> >>and then the buffer fills. The '245 handles that situation gracefully
> >>and will let your hardware know when it is no longer possible to
> >>accept data.
> >>
> >> Roger.
> >>
> >>>On 03.06.2015 12:40, Rogier Wolff wrote:
> >>>>On Tue, Jun 02, 2015 at 11:50:06AM +0200, d.rodomonti wrote:
> >>>>
> >>>>>ret = ftdi.usb_open(ftdic, 0x0403, 0x6001)
> >>>>>ret = ftdi.usb_reset(ftdic)
> >>>>>ret = ftdi.usb_purge_buffers(ftdic)
> >>>>>ret = ftdi.set_baudrate(ftdic, 115200)
> >>>>>ret = ftdi.set_line_property(ftdic, ftdi.BITS_8 , ftdi.STOP_BIT_1,
> >>>>>ftdi.NONE)
> >>>>>ret = ftdi.setflowctrl(ftdic,ftdi.SIO_DISABLE_FLOW_CTRL)
> >>>>How are you putting data into the '245?
> >>>>
> >>>>You are setting a baud rate and "disable flow control" which do not
> >>>>really make sense for a '245 chip.
> >>>>
> >>>> Roger.
> >>>>
> >>>>
> >>>--
> >>>--
> >>>
> >>>Davide Rodomonti
> >>>
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> --
> --
>
> Davide Rodomonti
>
>
> LOEP (Linac and Operations/ Electric Power System)
>
>
> Tel. +49-6159-71-1905
>
> BR2 2.107
>
>
> GSI Helmholtzzentrum für Schwerionenforschung GmbH
>
> Planckstraße 1
> 64291 Darmstadt
> www.gsi.de
>
>
> Gesellschaft mit beschränkter Haftung
> Sitz der Gesellschaft: Darmstadt
> Handelsregister: Amtsgericht Darmstadt, HRB 1528
>
> Geschäftsführung:
> Ursula Weyrich
> Professor Dr. Karlheinz Langanke
>
> Vorsitzender des Aufsichtsrates: St Dr. Georg Schütte
> Stellvertreter: Ministerialdirigent Dr. Rolf Bernhardt
>
>
>
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