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Bus and Memory Control (BCU, MEMC)
Chapter 7
Preliminary User’s Manual U17566EE1V2UM00
7.2.2
Chips select priority control
The chip select signals CS0 to CS7 can be assigned to overlapping memory
areas by setting the chip select area control registers CSC0 and CSC1. The
chip select priority control rules the generation of chip select signals in this
case.
Access to internal resources, which are concurrently mapped to an external
memory areas overrules the external access. As a consequence, the assigned
CSn signal is not generated externally.
If different chip select signals are set (CSC0.CSCkm = 1) for the same memory
bank, the priority order is as follows:
• internal resources > CS0 > CS2 > CS1 > CS3
• internal resources > CS7 > CS5 > CS6 > CS4
Examples:
• If both chip select signal CS0 and CS1 are set for memory bank 2, only the
chip select signal CS0 will be generated.
• If during access to bank 2 CS2 should
not
be active, activate CS0 for this
bank (CSC0.CS02 = 1). Due to the priority order, only chip select signal
CS0 will be active for bank 2.
7.2.3
Peripheral I/O area
Two areas of the address range are reserved for the registers of the on-chip
peripheral functions. These areas are called “peripheral I/O areas”:
(1)
Fixed peripheral I/O area
The fixed peripheral I/O area holds the registers of the on-chip peripheral I/O
functions.
Note
Because the address space covers 64 MB, the address bits A[31:26] are not
considered. Therefore, in this manual, all addresses of peripheral I/O registers
in the 4 KB peripheral I/O area are given in the range FFFF F000
H
to
FFFF FFFF
H
instead of 03FF F000
H
to 03FF FFFF
H
.
Table 7-3
Peripheral I/O areas
Name
Address range
Size
Fixed peripheral I/O area
03FF F000
H
to 03FF FFFF
H
4 KB
Programmable peripheral
I/O area (PPA)
Can be allocated at arbitrary addresses.
Base address is defined in the BPC register.
16 KB
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