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Specification Update 19
Intel
®
80219 General Purpose PCI Processor
Core Errata
15. Updating the JTAG parallel register requires an extra TCK rising edge
Problem: IEEE 1149.1 states that the effects of updating all parallel JTAG registers should be seen on the
falling edge of TCK in the Update-DR state. The Intel Xscale
®
core parallel JTAG registers
incorrectly require an extra TCK rising edge to make the update visible. Therefore, operations like
hold-reset, JTAG break, and vector traps require either an extra TCK cycle by going to
Run-Test-Idle or by cycling through the state machine again in order to trigger the expected
hardware behavior.
Workaround: When the JTAG interface is polled continuously, this erratum has no effect. When not, an extra
TCK cycle can be caused by going to Run-Test-Idle after writing a parallel JTAG register.
Status: NoFix.