Answers Database

BOUNDARY SCAN/JTAG: Sample/Preload in a XC5200 appears to work like BYPASS


Record #992

Product Family:  Hardware

Product Line:  5200

Problem Title:
BOUNDARY SCAN/JTAG: Sample/Preload in a XC5200 appears to work like
BYPASS



Problem Description:
Keywords: xc5200, sample/preload, bypass

Urgency: standard

General Description:
After loading the SAMPLE/PRELOAD instruction in a 5K device, the
data being shifted in to the device starts appearing on the TDO pin
one TCK later. In other words, the SAMPLE/PRELOAD instruction appears
to work like the BYPASS instruction.

Additionally, all other non 'sample/preload' instrutions appear
to work correctly.


Solution 1:

If the XC5200 /PROG pin is held low, the SAMPLE/PRELOAD instruction
can not be executed.  Before executing boundary scan instructions
in the XC5200, make sure that the /PROG pin is not held low.



End of Record #992