03-01-2012 05:55 PM
Hello,
I have a Spartan 3A starter board (HW-SPAR3A-SK-UNI-G) with the XC3S700A FPGA. I’d like to use its on-board USB JTAG interface to connect with external devices, namely the Spartan 3E XC3S500E-PQG208 and the XC95108 CPLD. In iMPACT, a scan of the JTAG chain results in a random number of devices being detected, which are labeled “unknown bypass,” if the chain scan stops at all. The external chips are confirmed to work stand-alone in another jig.
JTAG Chain Configuration:
Test Results:
Thoughtful suggestions appreciated.
03-18-2012 08:04 AM
We suppose to be not connect external devices in the JTAG chaing of Spartan-3A evalution board.
It seems to be the JTAG chaing connections loo is not proper. Plese refer configuration guide for more details