JTAG program failed

I have problems programming my EEPROM through JTAG. Most of the times it 
fails but I have succeeded once.
When programming the FPGA directly it works all the time.

I am using JTAG Cable Model IJC-2 from Insight
The EEPROM is a Xilinx XCF08P
The FPGA is a Xilinx Spartan 3 1500K gates

What can i try to correct this problem?
Is it possible to turn down the speed of the JTAG clock?

Thanks
Andreas Beier 

Andreas

I don't know the cable specifically but I am guessing you have a Parallel 
Cable III lookalike. These sorts of cable can sometimes be upset by a lowish 
programming head voltage or long cable runs.

Is your target board the one that came with the cable? If not you may need 
to look at voltages and routing on the board.

Have you extended the cable or using a laptop? Laptops sometimes have poorer 
drive on parallel ports and long cable lengths cause issues too.

Impact can change clocking rates but usually Parallel III cables will be 
running at the lowest rate anyway.

John Adair
Enterpoint Ltd. - Home of Raggedstone1. The 75� Spartan-3 Development Board.
http://www.enterpoint.co.uk



"mughat" <mughat@gmail.com> wrote in message 
news:e0j15e$rqn$1@news.net.uni-c.dk...
>I have problems programming my EEPROM through JTAG. Most of the times it 
>fails but I have succeeded once.
> When programming the FPGA directly it works all the time.
>
> I am using JTAG Cable Model IJC-2 from Insight
> The EEPROM is a Xilinx XCF08P
> The FPGA is a Xilinx Spartan 3 1500K gates
>
> What can i try to correct this problem?
> Is it possible to turn down the speed of the JTAG clock?
>
> Thanks
> Andreas Beier
>