CHAPTER 3 CPU FUNCTION
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User’s Manual U15195EJ5V0UD
(3) On-chip peripheral I/O area
4 KB of memory, addresses FFFF000H to FFFFFFFH, are provided as an on-chip peripheral I/O area.
An image of addresses FFFF000H to FFFFFFFH can be seen in the area between addresses 3FFF000H and
3FFFFFFH
Note
.
Note
Access to the area of addresses 3FFF000H to 3FFFFFFH is prohibited. To access the on-chip
peripheral I/O, specify addresses FFFF000H to FFFFFFFH.
FFFFFFFH
FFFF000H
On-chip peripheral I/O area
(4 KB)
On-chip peripheral I/O registers associated with the operation mode specification and the state monitoring for
the on-chip peripheral I/O are all memory-mapped to the on-chip peripheral I/O area. Program fetches
cannot be executed from this area.
Cautions 1. The least significant bit of an address is not decoded. Therefore, if byte access is
executed in the register at an odd address (2n + 1), the register at the even address (2n)
will be accessed because of the hardware specification.
2. In the V850E/IA2, no registers exist that are capable of word access, but if a register is
word accessed, halfword access is performed twice in the order of lower address, then
higher address of the word area, ignoring the lower 2 bits of the address.
3. For registers in which byte access is possible, if halfword access is executed, the
higher 8 bits become undefined during the read operation, and the lower 8 bits of data
are written to the register during the write operation.
4. Addresses that are not defined as registers are reserved for future expansion. If these
addresses are accessed, the operation is undefined and not guaranteed.
5. Addresses 3FFF000H to 3FFFFFFH cannot be specified as the source/destination
address of DMA transfer. Be sure to use addresses FFFF000H to FFFFFFFH for the
source/destination address of DMA transfer.
(4) External memory area
4 MB are available for external memory area.
•
Single-chip mode: x100000H to x3FFFFFH
•
ROMless mode: x000000H to x3FFFFFH
Note that the internal ROM, internal RAM, and on-chip peripheral I/O areas cannot be accessed as external
memory areas.
Содержание PD703114
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