On Apr 2, 5:09=A0pm, jleslie48 <j...@jonathanleslie.com> wrote:
> On Apr 2, 6:25 am, fpgauser <klausf...@gmail.com> wrote:
>
> > Hi,
>
> > =A0The cell BSCAN_SPARTAN3A allows to monitor the jtag input pins TCK,
> > TDI and TMS of a Spartan3A chip.
>
> > I was curious, whether I would also be able to capture the value of
> > the TDO pin (without soldering or wiring it back to another pin of the
> > 3AN)
>
> > If yes, what would be the trick?
>
> > Thanks in advance and bye
>
> well, I'm working with enterpoints raggedstone1, and I have the the 4
> pins of the jtag readily available to my
> top.vhd:
>
> 1) =A0my .ucf file:
>
> #-- FPGA pin JTAG signals
>
> #-- WARNING!!!!!! =A0MAKE SURE THESE ARE USED IF YOU
> #-- REPROGRAM THE PROMS!!! =A0FAILURE TO DO SO WILL
> #-- DISABLE THE JTAG. =A0BRING THESE PINS IN, AND MAKE
> #-- A DUMMY OUTPUT FOR THEM.
>
> NET "TCK" =A0LOC =3D "C11" | IOSTANDARD =3D LVTTL ;
> NET "TDI" =A0LOC =3D "E11" | IOSTANDARD =3D LVTTL ;
> NET "TDO" =A0LOC =3D "B20" | IOSTANDARD =3D LVTTL ;
> NET "TMS" =A0LOC =3D "B11" | IOSTANDARD =3D LVTTL ;
>
> NET "JTAG_OR_DUMMY" =A0 LOC =3D "T21" | IOSTANDARD =3D LVTTL ;
>
> and in my top.vhd I've added:
>
> -- preserve the pinouts for the Jtag.
> =A0 =A0 jtag_or_dummy =A0 <=3D
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0TCK =A0OR
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0TDI =A0OR
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0TDO =A0OR
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0TMS ;
>
> END BEHAVORIAL;
>
> and the those labels to the port.

those pins are NOT FPGA JTAG pins !!

its extra jtag chain connected to FPGA IO, but not to FPGA JTAG

Antti

On Apr 2, 6:25 am, fpgauser <klausf...@gmail.com> wrote:
> Hi,
>
>  The cell BSCAN_SPARTAN3A allows to monitor the jtag input pins TCK,
> TDI and TMS of a Spartan3A chip.
>
> I was curious, whether I would also be able to capture the value of
> the TDO pin (without soldering or wiring it back to another pin of the
> 3AN)
>
> If yes, what would be the trick?
>
> Thanks in advance and bye

well, I'm working with enterpoints raggedstone1, and I have the the 4
pins of the jtag readily available to my
top.vhd:

1)  my .ucf file:

#-- FPGA pin JTAG signals

#-- WARNING!!!!!!  MAKE SURE THESE ARE USED IF YOU
#-- REPROGRAM THE PROMS!!!  FAILURE TO DO SO WILL
#-- DISABLE THE JTAG.  BRING THESE PINS IN, AND MAKE
#-- A DUMMY OUTPUT FOR THEM.

NET "TCK"  LOC = "C11" | IOSTANDARD = LVTTL ;
NET "TDI"  LOC = "E11" | IOSTANDARD = LVTTL ;
NET "TDO"  LOC = "B20" | IOSTANDARD = LVTTL ;
NET "TMS"  LOC = "B11" | IOSTANDARD = LVTTL ;

NET "JTAG_OR_DUMMY"   LOC = "T21" | IOSTANDARD = LVTTL ;


and in my top.vhd I've added:


-- preserve the pinouts for the Jtag.
    jtag_or_dummy   <=
                       TCK  OR
                       TDI  OR
                       TDO  OR
                       TMS ;

END BEHAVORIAL;

and the those labels to the port.

On Apr 2, 1:25=A0pm, fpgauser <klausf...@gmail.com> wrote:
> Hi,
>
> =A0The cell BSCAN_SPARTAN3A allows to monitor the jtag input pins TCK,
> TDI and TMS of a Spartan3A chip.
>
> I was curious, whether I would also be able to capture the value of
> the TDO pin (without soldering or wiring it back to another pin of the
> 3AN)
>
> If yes, what would be the trick?
>
> Thanks in advance and bye

No

you only know the TDO value IF the TAP is in USER1/USER2 and DRSCAN
state
but the value is what you shift out, so you would know it anyway...

Antti

Hi,

 The cell BSCAN_SPARTAN3A allows to monitor the jtag input pins TCK,
TDI and TMS of a Spartan3A chip.

I was curious, whether I would also be able to capture the value of
the TDO pin (without soldering or wiring it back to another pin of the
3AN)

If yes, what would be the trick?

Thanks in advance and bye