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  3. AR# 194: JTAG - How to use EXTEST instruction before configuration in a XC4K/XC5K device?

AR# 194

JTAG - How to use EXTEST instruction before configuration in a XC4K/XC5K device?

Description

Keywords: xc4000, xc5200, extest, program pin, JTAG

Urgency: standard

General Description:

How to execute the EXTEST instruction before configuration?

Solution

If the /PROGRAM pin is held low, the Boundary Scan registers for EXTEST
will reset and not work. Releasing /PROGRAM, but holding the INIT low will halt configuration
just at the start. With the INIT signal held low, you may then
execute the EXTEST instruction.

The only other way to use the EXTEST instruction is to do so after
configuration has completed.
AR# 194
Date 09/30/2008
Status Archive
Type General Article