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JTAG Circuitry for Debug
JTAG Circuitry for Debug
11
Certain restrictions exist in order to use JTAG based debuggers with the Intel XScale
®
microarchitecture. This is primarily due to the Tap Controller reset requirements of the Intel
XScale
®
microarchitecture and the reset requirements of specific JTAG debuggers. The following
outlines these requirements along with suggestions for circuitry to alleviate potential problems
11.1
Requirements
The (Intel
®
80331 I/O processor (80331), like many others, requires that nTRST (Tap Reset) is
asserted during power up. This is to ensure a fully initialized boundary scan chain. Failure to
comply with this requirement may result in spurious behavior of the application.
The ARM* Multi-ICE* JTAG debugger requires that nTRST is always weakly pulled high. This
requirement stems from the fact that the debugger can only assert nTRST (drive low). Both reset
signals coming from the Multi-ICE
™
(nTRST and nSRST) are open collector and must be weakly
pulled high in order to avoid unintentional resets (System or TAP).
Содержание 80331
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