4.3.4. c0, TCM Type Register

The TCMTR characteristics are:


Informs the processor of the number of ATCMs and BTCMs in the system

Usage constraints

The TCMTR is:

  • a read-only register

  • accessible in Privileged mode only.


Available in all processor configurations.


Figure 4.9 shows the TCMTR bit assignments.

Figure 4.9. TCMTR Register bit assignments

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Table 4.5 shows the TCMTR bit assignments.

Table 4.5. TCMTR Register bit assignments


Name Function
[31:29]-Always 0, indicating v6 format TCMTR.
[18:16]BTCM Specifies the number of BTCMs implemented. This is always set to b001 because the processor has one BTCM.
[2:0]ATCM Specifies the number of ATCMs implemented. Always set to b001. The processor has one ATCM.

To access the TCMTR, read CP15 with:

MRC p15, 0, <Rd>, c0, c0, 2 ; Returns TCMTR


  • The ATCM and BTCM fields in the TCMTR occupy the same space respectively as the ITCM and DTCM fields as defined by the ARM architecture. These fields, and the corresponding TCM interfaces, can be considered equivalent to those defined in the ARM architecture.

  • The ARM architecture requires only the ITCM to be accessible from both instruction and data sides. In the Cortex-R4 processor, both ATCM and BTCM are accessible from both instruction and data sides.

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