CHAPTER 4 CPU ARCHITECTURE
Page 59 of 920
4.2.5
Extended special function registers (2nd SFRs: 2nd Special Function
Registers)
Unlike a general-purpose register, each extended SFR (2
nd
SFR) has a special function.
Extended SFRs are allocated to the F0000H to F07FFH area. SFRs other than those in the SFR area (FFF00H
to FFFFFH) are allocated to this area. An instruction that accesses the extended SFR area, however, is 1 byte
longer than an instruction that accesses the SFR area.
Extended SFRs can be manipulated like general-purpose registers, using operation, transfer, and bit
manipulation instructions. The manipulable bit units, 1, 8, and 16, depend on the SFR type.
Each manipulation bit unit can be specified as follows.
• 1-bit manipulation
Describe as follows for the 1-bit manipulation instruction operand (!addr16.bit)
When the bit name is defined: <Bit name>
When the bit name is not defined: <Register name>.<Bit number> or <Address>.<Bit number>
• 8-bit manipulation
Describe the symbol defined by the assembler for the 8-bit manipulation instruction operand (!addr16). This
manipulation can also be specified with an address.
• 16-bit manipulation
Describe the symbol defined by the assembler for the 16-bit manipulation instruction operand (!addr16). When
specifying an address, describe an even address.
Tables 4 - 10 to 4 - 16 give lists of the extended SFRs. The meanings of items in the table are as follows.
• Symbol
This item indicates the address of an extended SFR. It is a reserved word in the assembler, and is defined as
an sfr variable using the #pragma sfr directive in the compiler. When using the assembler, debugger, and
simulator, symbols can be written as an instruction operand.
• R/W
This item indicates whether the corresponding extended SFR can be read or written.
R/W: Read/write enable
R: Read only
W: Write only
• Manipulable bit units
“
√
” indicates the manipulable bit unit (1, 8, or 16). “—” indicates a bit unit for which manipulation is not possible.
• After reset
This item indicates each register status upon reset signal generation.
Caution
Do not access addresses to which extended SFRs are not assigned.
Remark
For SFRs in the SFR area, see
4.2.4 Special function registers (SFRs)
.
Summary of Contents for RL78/G1H
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