Hi Jo,
I've been working on a project where I configure an FPGA (Cyclone II)
using the FT232RL, from my understanding the two are very similar to
communicate with.
I mentioned in my blog post
(http://idle-logic.com/2011/03/05/programming-an-altera-cyclone-ii-fpga-with-a-ft232rl-python-code)
that I was having problems using the SetBitMode function, I don't
recall why but it wasn't working for me at the time. The documentation
said it's depreciated, but I ended up using the enable_bitbang
function instead and it worked for me.
I'm curious what you're using to program the FPGA, a 3rd party
application? Possibly it uses the libftd2xx library and there is a
glitch on the handover to the libftdi library?
If that NCONFIG pin gets pulled low you'll reset the FPGA into
configuration mode, which is what I'm guessing is happening. If you
set the NCONFIG to an output and keep it high does the device also
reset?
Just throwing out some ideas... perhaps someone with more experience
can chime in :-)
Best regards,
Chris Zeh
On Mon, Jul 25, 2011 at 3:45 PM, Joachim Schambach
<jschamba@xxxxxxxxxxxxxxxxxx> wrote:
> Hi,
> I have a question about the usage of the ftdi_set_bitmode function.
> I am using a development board from FTDI called MorphIC-II to evaluate the
> usage
> of the FT2232HQ chip. This board uses the A port as an IO port to communicate
> with a Cyclone FPGA, and the B-Port is connected to the programming pins of
> the
> FPGA as follows:
> BD[0] = DCLK
> BD[1] = DATA0
> BD[2] = NCONFIG
> BD[3] = NSTATUS
> BD[4] = CONF_DONE
> BD[7] = DEV_RST
>
> I am trying to use BITBANG mode to port B to set the DEV_RST line to 0, while
> leaving the other pins alone (by setting them as inputs). I have been able to
> do
> this with the libftd2xx library as follows:
> -----------ftd2xx code---------------------
> ftStatus = FT_Open(1, &fthandle1);
> UCHAR Mask = 0x80; // only bit 7 is output
> UCHAR Mode = 1;
> // Set bit-bang mode
> ftStatus = FT_SetBitMode(fthandle1, Mask, Mode);
> UCHAR Value = 0x0; //set all bits to 0
> ftStatus = FT_Write(fthandle1, &Value, 1, &BytesWritten);
> ------------end ftd2xx code -------------------
>
> I am now trying to do the same thing with the libftdi library as follows:
>
> ----------libftdi code ---------------------------
> ftdi_init(&ftdic2)
> ftdi_set_interface(&ftdic2, INTERFACE_B);
> ftdi_usb_open(&ftdic2, 0x0403, 0x6010));
> ftdi_set_bitmode(&ftdic2, 0x80, BITMODE_BITBANG);
> buf[0] = 0x0;
> ftdi_write_data(&ftdic2, buf, 1);
> -------- end libftdi code------------------------
>
> But as soon as the ftdi_set_bitmode function is called, the FPGA seems to
> reconfigure, as if one of the other pins (other than pin7) gets toggled.
>
> Am I misunderstanding how to use the bitmask in this call? Or is there some
> other problem that prevents me from using this library with this chip?
>
> Regards,
> Jo
>
> --
> 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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>
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