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CHAPTER 3 CPU ARCHITECTURE
User’s Manual U15798EJ2V0UD
3.2.3 Special-function registers (SFR)
Unlike a general-purpose register, each special function register has a special functions.
They are allocated to the FF00H to FFFFH area.
The special function registers can be manipulated like general-purpose registers, with operation, transfer and bit
manipulation instructions. The manipulatable bit units, 1, 8, and 16, depend on the special function register type.
Each manipulation bit unit can be specified as follows.
• 1-bit manipulation
Describe the symbol reserved in the assembler for the 1-bit manipulation instruction operand (sfr.bit).
This manipulation can also be specified with an address.
• 8-bit manipulation
Describe the symbol reserved in the assembler for the 8-bit manipulation instruction operand (sfr).
This manipulation can also be specified with an address.
• 16-bit manipulation
Describe the symbol reserved in the assembler for the 16-bit manipulation instruction operand (sfrp).
When addressing an address, describe an even address.
Table 3-3 gives a list of special function registers. The meaning of items in the table is as follows.
• Symbol
Symbol indicating the address of a special function register. It is a reserved word in the RA78K0, and is defined
via the header file “sfrbit.h” in the CC78K0. When using the RA78K0, ID78K0-NS, or SM78K0, symbols can
be written as an instruction operand.
• R/W
Indicates whether the corresponding special function register can be read or written.
R/W: Read/write enable
R:
Read only
W:
Write only
• Manipulatable bit units
Indicates the manipulatable bit unit (1, 8, or 16). “–” indicates a bit unit for which manipulation is not possible.
• After reset
Indicates each register status upon RESET input.
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