Motorola MPC8260 - Manual (Page 172)

4-34 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA
Part II. ConÞguration and Reset
4.3.2.7 Internal Memory Map Register (IMMR)
The internal memory map register (IMMR), shown in Figure 4-29, contains identiÞcation
of a speciÞc device as well as the base address for the internal memory map. Software can
deduce availability and location of any on-chip system resources from the values in IMMR.
PARTNUM and MASKNUM are mask programmed and cannot be changed for any
particular device.
Table 4-13 describes IMMR Þelds.
Bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Field ISB Ñ
Reset Depends on reset conÞguration sequence. See Section 5.4.1, ÒHard Reset ConÞguration Word.Ó
R/W R/W
Addr 0x101A8
Bit 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Field PARTNUM MASKNUM
Reset Ñ
R/W R
Addr 0x101AA
Figure 4-29. Internal Memory Map Register (IMMR)
Table 4-13. IMMR Field Descriptions
Bits Name Description
0Ð14 ISB Internal space base. DeÞnes the base address of the internal memory space. The value of ISB
be conÞgured at reset to one of 32 addresses; it can then be changed to any value by the
software. The default is 0, which maps to address 0x0000_0000.
ISB deÞnes the 15 msbs of the memory map register base address. IMMR itself is mapped in
the internal memory space region. As soon as the ISB is written with a new base address, the
IMMR base address is relocated according to the ISB. ISB can be conÞgured to one of 32
possible addresses at reset to enable the conÞguration of multiple-MPC8260 systems.
The number of programmable bits in this Þeld, and hence the resolution of the location of
internal space, depends on the internal memory space of a speciÞc implementation. In the
MPC8260, all 15 bits can be programmed. See Chapter 3, ÒMemory Map,Ó for details on the
deviceÕs internal memory map and to Chapter 5, ÒReset,Ó for the available, default initial values.
15 Ñ Reserved, should be cleared.
16Ð23 PARTNUM Part number. This read-only Þeld is mask-programmed with a code corresponding to the part
number of the part on which the SIU is located. It is intended to help factory test and user code
which is sensitive to part changes. This changes when the part number changes. For example,
it would change if any new module is added or if the size of any memory module is changed. It
would not change if the part is changed to Þx a bug in an existing module. The MPC8260 has an
ID of 0x00.
24Ð31 MASKNUM Mask number. This read-only Þeld is mask-programmed with a code corresponding to the mask
number of the part on which the SIU is located. It is intended to help factory test and user code
which is sensitive to part changes. It is programmed in a commonly changed layer and should
be changed for all mask set changes. The MPC8260 (Rev 0) has an ID of 0x00.