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5.2.3 Special function register (SFR)
Unlike a general register, each special function register has special functions.
It is allocated in the FF00H to FFFFH area.
The special function register can be manipulated, like the general register, with the operation, transfer and bit
manipulation instructions. 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
Describes the symbol reserved with assembler for the 1 bit manipulation instruction operand (sfr.bit). This
manipulation can also be specified with an address.
• 8-bit manipulation
Describes the symbol reserved with assembler for the 8-bit manipulation instruction operand (sfr). This
manipulation can also be specified with an address.
• 16-bit manipulation
Describes the symbol reserved with assembler for the 16-bit manipulation instruction operand (sfrp). When
addressing an address, describe an even address.
Table 5-5 gives a list of special function registers. The meaning of items in the table is as follows.
• Symbols
A symbol indicates an address of the special function register. Symbols are reserved words in RA78K/0
and have been defined by a header file sfrbt.h in CC78K/0. They can be used as instruction operands when
RA78K/0, ID78K0, or SD78K/0 is used.
• R/W
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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
The register can be manipulated in bit units (1, 8, and 16) marked with " ".
The register cannot be manipulated in bit units marked with "—".
• When reset
Indicates each register status upon RESET input.
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CHAPTER 5 CPU ARCHITECTURE
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