JTAG implementation

Hello everybody. I'm interested in developing a JTAG system using a FPGA 
programmed in VHDL. Is there some good source on line that can help me 
in doing that? Where can I found the specification of JTAG standard? Are 
they free available?
If I am OT can you say me that?
Thanks a lot

"Giovanni" <giovanni.parodi79NOSPAM@lycos.it> wrote in message
news:MPG.1adc8be5bc13c10d989692@208.234.59.139...
> Hello everybody. I'm interested in developing a JTAG system using a FPGA
> programmed in VHDL. Is there some good source on line that can help me
> in doing that? Where can I found the specification of JTAG standard? Are
> they free available?
> If I am OT can you say me that?
> Thanks a lot

Most FPGAs already have a JTAG port through which you can program the part.
Have you checked your FPGA's data sheet for this?
Search online for the JTAG standard - it's IEEE, so you'll plenty of hits.

Cheers
Bhaskar

In article <c4ulrc$2m4pav$1@ID-82263.news.uni-berlin.de>, 
bhaskart@deja.com says...
> "Giovanni" <giovanni.parodi79NOSPAM@lycos.it> wrote in message
> news:MPG.1adc8be5bc13c10d989692@208.234.59.139...
> > Hello everybody. I'm interested in developing a JTAG system using a FPGA
> > programmed in VHDL. Is there some good source on line that can help me
> > in doing that? Where can I found the specification of JTAG standard? Are
> > they free available?
> > If I am OT can you say me that?
> > Thanks a lot
> 
> Most FPGAs already have a JTAG port through which you can program the part.
> Have you checked your FPGA's data sheet for this?
> Search online for the JTAG standard - it's IEEE, so you'll plenty of hits.
> 
> Cheers
> Bhaskar
> 
> 
> 
I'm sorry, my english is very bad, may be I don't explain what I want to 
do. I want to realize a Jtag interface using a FPGA, to control a DSP or 
others devices that can be controlled with this interface. Is there some 
hint, good idea to do that? And the standard is free?

"Giovanni" <giovanni.parodi79NOSPAM@lycos.it> wrote in message
news:MPG.1ade0371e8e28790989694@208.234.59.139...
> In article <c4ulrc$2m4pav$1@ID-82263.news.uni-berlin.de>,
> bhaskart@deja.com says...
> > "Giovanni" <giovanni.parodi79NOSPAM@lycos.it> wrote in message
> > news:MPG.1adc8be5bc13c10d989692@208.234.59.139...
> > > Hello everybody. I'm interested in developing a JTAG system using a
FPGA
> > > programmed in VHDL. Is there some good source on line that can help me
> > > in doing that? Where can I found the specification of JTAG standard?
Are
> > > they free available?
> > > If I am OT can you say me that?
> > > Thanks a lot
> >
> > Most FPGAs already have a JTAG port through which you can program the
part.
> > Have you checked your FPGA's data sheet for this?
> > Search online for the JTAG standard - it's IEEE, so you'll plenty of
hits.
> >
> > Cheers
> > Bhaskar
> >
> >
> >
> I'm sorry, my english is very bad, may be I don't explain what I want to
> do. I want to realize a Jtag interface using a FPGA, to control a DSP or
> others devices that can be controlled with this interface. Is there some
> hint, good idea to do that? And the standard is free?

Amontec in Switzerland sells something like this with a Coolrunner CPLD
inside it. It emulates lots of different JTAG interfaces by reconfiguring
the CPLD via the PC printer port.

Leon

Leon