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| Home > Program Trace Macrocell Programmers Model > About the access permissions for PTM registers > Effect of DBGSWENABLE on register access | |||
The ARM Debug Interface version 5 defines a signal, DBGSWENABLE, that can be used to disable access to some of the processor registers. If this interface is implemented, from PFTv1.1, then DBGSWENABLE has the following effects on accesses to the PTM registers:
DBGSWENABLE has no effect on external debugger accesses.
If DBGSWENABLE is LOW, then memory-mapped accesses to all PTM registers return Error, otherwise accesses are unaffected.
DBGSWENABLE has no effect on coprocessor accesses to PTM registers.
To ensure that on-chip software can save and restore PTM registers, ARM recommends that DBGSWENABLE is held HIGH.
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