4.3.2. CPUID Base Register, CPUID

The CPUID characteristics are:



  • the ID number of the processor core

  • the version number of the processor core

  • the implementation details of the processor core.

Usage Constraints

There are no usage constraints.


This register is available in all processor configurations.


See the register summary in Table 4.1.

Figure 4.2 shows the CPUID bit assignments.

Figure 4.2. CPUID bit assignments

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Table 4.3 shows the CPUID bit assignments.

Table 4.3. CPUID bit assignments

[31:24]IMPLEMENTERIndicates implementer: 0x41 = ARM
[23:20]VARIANTIndicates processor revision: 0x2 = Revision 2
[19:16](Constant)Reads as 0xF
[15:4]PARTNOIndicates part number: 0xC23 = Cortex-M3
[3:0]REVISIONIndicates patch release: 0x1 = Patch 1.

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