6.3.7. c9, Cycle Count Register

The PMCCNTR Register characteristics are:


Counts clock cycles.

Usage constraints

The PMCCNTR Register:

  • Is a 32-bit read/write register.

  • Is accessible in:

  • Must be disabled before software can write to it. Any attempt by software to write to this register when enabled is Unpredictable.


Available in all processor configurations.

To access the PMCCNTR read or write CP15 with:

MRC p15, 0, <Rd>, c9, c13, 0 ; Read  PMCCNTR Register
MCR p15, 0, <Rd>, c9, c13, 0 ; Write PMCCNTR Register
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