M16C/62P Group (M16C/62P, M16C/62PT)
9. Memory Space Expansion Function
Rev.2.41
Jan 10, 2006
Page 72 of 390
REJ09B0185-0241
9.
Memory Space Expansion Function
The following describes a memory space extension function.
During memory expansion or microprocessor mode, the memory space expansion function allows the access space to
be expanded using the appropriate register bits.
Table 9.1 shows The Way of Setting Memory Space Expansion Function, Memory Space.
9.1
1-Mbyte Mode
In this mode, the memory space is 1 Mbytes. In 1-Mbyte mode, the external area to be accessed is specified using
the CSi (i = 0 to 3) signals (hereafter referred to as the CSi area). Figures 9.2 to 9.3 show the Memory Mapping and
CS Area in 1-Mbyte mode.
9.2
4-Mbyte Mode
In this mode, the memory space is 4 Mbytes. Figure 9.1 shows the DBR Register. The BSR2 to BSR0 bits in the
DBR register select a bank number which is to be accessed to read or write data. Setting the OFS bit to “1” (with
offset) allows the accessed address to be offset by 40000h.
In 4-Mbyte mode, the CSi (i=0 to 3) pin functions differently for each area to be accessed.
9.2.1
9.2.1 Addresses 04000h to 3FFFFh, C0000h to FFFFFh
•
The CSi signal is output from the CSi pin (same operation as 1-Mbyte mode. However, the last address of
CS1 area is 3FFFFh).
9.2.2
9.2.2 Addresses 40000h to BFFFFh
•
The CS0 pin outputs “L”
•
The CS1 to CS3 pins output the value of setting as the BSR2 to BSR0 bits (bank number)
Figures 9.4 to 9.5 show the Memory Mapping and CS Area in 4-Mbyte mode. Note that banks 0 to 6 are data-only
areas. Locate the program in bank 7 or the CSi area.
Table 9.1
The Way of Setting Memory Space Expansion Function, Memory Space
Memory Space Expansion Function
How to Set (PM15 to PM14)
Memory Space
1-Mbyte Mode
00b
1 Mbyte (no expansion)
4-Mbyte Mode
11b
4 Mbytes
The M16C/62P (80-pin version) and M16C/62PT do not use the memory space expansion function.
Note
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