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
Can I capture the jtag TDO pin of a Spartan3AN
Started by ●April 2, 2009
Reply by ●April 2, 20092009-04-02
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 byeNo 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
Reply by ●April 2, 20092009-04-02
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 byewell, 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.
Reply by ●April 2, 20092009-04-02
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