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MC9S12VR-Family - Data Sheet - Freescale Semiconductor

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S12G Memory Map Controller (S12GMMCV1)<br />

3.4.3 Unimplemented and Reserved Address Ranges<br />

The S12GMMC is capable of mapping up 64K of flash, 512 bytes of EEPROM and 2K of RAM into the<br />

global memory map{statement}. Smaller devices of theS12VR-family do not utilize all of the available<br />

address space. Address ranges which are not associated with one of the on-chip memories fall into two<br />

categories: Unimplemented addresses and reserved addresses.<br />

Unimplemented addresses are not mapped to any of the on-chip memories. The S12GMMC is aware that<br />

accesses to these address location have no destination and triggers a system reset (illegal address reset)<br />

whenever they are attempted by the CPU. The BDM is not able to trigger illegal address resets.<br />

Reserved addresses are associated with a memory block on the device, even though the memory block does<br />

not contain the resources to fill the address space. The S12GMMC is not aware that the associated memory<br />

does not physically exist. It does not trigger an illegal address reset when accesses to reserved locations<br />

are attempted.<br />

Table 3-9 shows the global address ranges of all members of the S12VR-family.<br />

Table 3-9. Global Address Ranges<br />

0x00000-<br />

0x003FF<br />

0x00400-<br />

0x005FF<br />

0x00800-<br />

0x037FF<br />

0x03800-<br />

0x03FFF<br />

0x04000-<br />

0x07FFF<br />

(NVMRES<br />

=1)<br />

0x04000-<br />

0x07FFF<br />

(NVMRES<br />

=0)<br />

0x08000-<br />

0x30000<br />

0x30000-<br />

0x33FFF<br />

S12VR48 S12VR64<br />

Register Space<br />

0.5k<br />

EEPROM<br />

Unimplemented<br />

3.4.4 Prioritization of Memory Accesses<br />

On S12VR devices, the CPU and the BDM are not able to access the memory in parallel. An arbitration<br />

occurs whenever both modules attempt a memory access at the same time. CPU accesses are handled with<br />

<strong>MC9S12VR</strong> <strong>Family</strong> Reference Manual, Rev. 2.8<br />

114 <strong>Freescale</strong> <strong>Semiconductor</strong><br />

RAM<br />

2k<br />

Internal NVM Resources<br />

Unimplemented<br />

Reserved Flash<br />

0x34000-<br />

0x3FFFF 48k 64k

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