Hi,
I experimented some more with both drivers and just discovered another
weirdness. maybe i need to send this as a separate subject thread to this list,
but since it is happening with the same module, maybe this is related.
I wrote a simple application that just uses ftdi_write_data to send some data to
the MorphIC-II on channel A of the FT2232 and then observe the FPGA signals in
signaltap. Initially I thought this was working correctly, but when I tried to
execute the same application twice, the second time around I don't observe the
AC[0] line (RXF#) going low, i.e. no data is being received into the FIFO from
the Linux box. Yet on the Linux side, the call returns with no error, as if the
call succeeded.
After some experimentation, I finally found that everything worked correctly
again when I added a second ftdi_write_data call, even if that one only sent 1
byte.
So I tried the same thing with the libftd2xx library from FTDI, and indeed, that
one behaved the same way.
However, when trying the same experiment on a Windows machine with the same FPGA
firmware, everything behaves as expected, i.e. repeatedly executing an FT_WRITE
(even a single call) worked all the time.
So either I am missing something fundamentally, or something is weird with the
Linux USB implementation. And yes, I did call rmmod ftdi_sio and rmmod
usbserial.
Totally confused....
Cheers,
Jo
On 7/26/2011 9:31 AM, Chris Zeh wrote:
> Hi Jo,
>
> It is curious the difference between the two drivers, I'm hoping the
> suggestions I sent you will help get everything going.
>
> I'm looking at the schematics for the Morph, pg27 and it looks like
> the pull-ups are on the FPGA side. (possibly this is a different
> product than what you're
> using?).(http://www.ftdichip.com/Support/Documents/DataSheets/Modules/DS_Morph-IC-II.pdf)
>
> Going through the documentation it looks like this board is designed
> to program the FPGA using the Passive Serial (PS) configuration, which
> would be using the FTDI instead of the JTAG. Typically if you're using
> the JTAG to program the FPGA you would tie the MSEL[0:1] lines to GND.
> (See page 409 http://www.altera.com/literature/hb/cyc2/cyc2_cii5v1.pdf).
> Although JTAG is a bully and can program the FPGA no matter what the
> MSEL pins are set too. I believe tying these lines to GND will make
> the FPGA insensitive to glitches on the NCONFIG line. Looking at the
> board schematics this might not be possible.
>
> Just some more details in case you're planning on laying out your own
> board down the line...
>
> Let us know how it goes.
>
> Best regards,
> Chris
>
>
>
>
> On Tue, Jul 26, 2011 at 7:37 AM, Joachim Schambach
> <jschamba@xxxxxxxxxxxxxxxxxx> wrote:
>> From the schematics that FTDI provides it looks like there are no pullups or
>> pulldowns on those lines, maybe the FPGA itself has some internal
>> pullups/downs.
>> However, as you noticed, everything seems to work with the libftd2xx.
>> The only reason I am working on this is that I noticed that the DEV_RST is
>> set
>> high, when I do nothing to the B port. So all I am trying to accomplish is
>> setting this one line to 0. Any functionality that can do this would work
>> for
>> me, I just thought BITBANG would be the easiest.
>> Jo
>>
>> On 7/26/2011 4:28 AM, Uwe Bonnes wrote:
>>>>>>>> "Joachim" == Joachim Schambach <jschamba@xxxxxxxxxxxxxxxxxx> writes:
>>> Joachim> Hi, I have a question about the usage of the ftdi_set_bitmode
>>> Joachim> function. I am using a development board from FTDI called
>>> Joachim> MorphIC-II to evaluate the usage of the FT2232HQ chip. This
>>> ...
>>> Joachim> I am trying to use BITBANG mode to port B to set the DEV_RST
>>> Joachim> line to 0, while leaving the other pins alone (by setting them
>>> Joachim> as inputs). I have been able to do this with the libftd2xx
>>>
>>> What are you trying to achieve? What other function should the FT2232H do,
>>> either seqential or simultanious? Why can't you use MPSSE to set the PINs?
>>>
>>> Otherwise, are there appropriate pull-up/downs to keep the input lines from
>>> floating? But as it works with ftd2xx, there should be.
>>>
>>> In the next weeks I don't have time to investigate further...
>>>
>>> Bye
>>>
>> --
>> Dr Joachim Schambach tel: x1 512 471 1303
>> The University of Texas at Austin fax: x1 814 295 5111
>> Department of Physics email: jschamba@xxxxxxxxxxxxxxxxxx
>> 1 University Station C1600
>> Austin, Texas 78712-0264, USA
>>
>>
>> --
>> 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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--
Dr Joachim Schambach tel: x1 512 471 1303
The University of Texas at Austin fax: x1 814 295 5111
Department of Physics email: jschamba@xxxxxxxxxxxxxxxxxx
1 University Station C1600
Austin, Texas 78712-0264, USA
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