Debug Test Access Port
ARM DDI 0301H Copyright © 2004-2009 ARM Limited. All rights reserved. 14-2
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14.1 Debug Test Access Port and Debug state
In Debug state, JTAG-based hardware provides access to the processor and debug unit. Access
is through scan chains and the Debug Test Access Port (DBGTAP). The DBGTAP state Machine
(DBGTAPSM) is illustrated in Figure 14-1.
Figure 14-1 JTAG DBGTAP state machine diagram
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1. From IEEE Std 1149.1-2001. Copyright 2001 IEEE. All rights reserved.
tms=1
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Run-Test/Idle
Test-Logic-
Reset
Select-DR-Scan Select-IR-Scan
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Capture-DR
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Capture-IR
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Shift-IR
Exit1-IR
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Pause-IR
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Exit2-IR
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Update-IR
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Shift-DR
Exit1-DR
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Pause-DR
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Exit2-DR
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Update-DR
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