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PC to JTAG

Started by Matthew Hicks May 25, 2007
I read all of the documents I could find about using the JTAG port as a communications 
interface to the FPGA and implemented my own JTAG controlled logic.  The 
problem is, none of the documents that I read gave a decent solution as to 
how to get access to the JTAG chain on the PC side of things.  I am using 
the Virtex II-Pro XUP board which has a USB front end to the JTAG interface. 
 Is there an existing software solution available that I can use to send 
data to the user JTAG registers?  If not, then is there a Xilinx API that 
I need to use to write a program to do it myself or do I need to use a standard 
USB library?  Finally, once I am able to send data to the board's USB interface, 
is there a protocol that I need to follow to work with the Cypress USB chip 
or can I just send raw JTAG commands as the data payload?


---Matthew Hicks


Matthew Hicks schrieb:
> I read all of the documents I could find about using the JTAG port as a communications > interface to the FPGA and implemented my own JTAG controlled logic. The > problem is, none of the documents that I read gave a decent solution as to > how to get access to the JTAG chain on the PC side of things. I am using > the Virtex II-Pro XUP board which has a USB front end to the JTAG interface. > Is there an existing software solution available that I can use to send > data to the user JTAG registers? If not, then is there a Xilinx API that > I need to use to write a program to do it myself or do I need to use a standard > USB library? Finally, once I am able to send data to the board's USB interface, > is there a protocol that I need to follow to work with the Cypress USB chip > or can I just send raw JTAG commands as the data payload? > > > ---Matthew Hicks
No. you can talk to almst any other interface but not to the xilinx platform cable as xilinx does not make the protocol info available. so, in generic talking to JTAG from PC is piece of cake. but if the interface is xilinx platform usb, you just cant do it, unless you load 3rd party firmware into the cypress chip... Antti