CHAPTER 3 CPU ARCHITECTURE
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User’s Manual U11302EJ4V0UM
3.2.3 Special-function registers (SFRs)
Unlike a general-purpose register, each special-function register has a special function. The special-function
registers are allocated in the FF00H to FFFFH area.
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
Indicates symbols that specify the addresses of the special-function registers. The RA78K0 uses these
symbols as reserved words, and the CC78K0 defines them in the header file “sfrbit.h”. Symbols can be used
as instruction operands if the RA78K0, ID78K0, or SD78K0 is used.
• 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 manipulatable bit units (1, 8, and 16). – indicates unmanipulatable bit units.
• After reset
Indicates each register status upon RESET input.
