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CHAPTER 3 CPU ARCHITECTURE
User’s Manual U12697EJ3V0UM
3.9 Special Function Registers (SFRs)
These registers are assigned special functions such as the mode register and control register of the on-chip
peripheral hardware and are mapped to the 256-byte area from 0FF00H to 0FFFFH
Note
.
Note
These are the addresses when the LOCATION 0H instruction is executed. They are FFF00H to FFFFFH
when the LOCATION 0FH instruction is executed.
Caution In this area, do not access an address that is not allocated by an SFR. If erroneously accessed,
the
µ
PD784225 enters the deadlock state. The deadlock state is released only by reset input.
Table 3-6 shows the list of special function registers (SFRs). The meanings of the items are described next.
•
Symbol ............................ This symbol indicates the on-chip SFR. In NEC assembler RA78K4, this is a reserved
word. In C compiler CC78K4, it can be used as an sfr variable by a #pragma sfr
directive.
•
R/W ................................. Indicates whether the corresponding SFR can be read or written.
R/W: Can read/write
R:
Read only
W:
Write only
•
Bit Manipulation Unit ...... When the corresponding SFR is manipulated, the appropriate bit manipulation unit
is indicated. An SFR that can manipulate 16 bits can be described in the sfrp operand.
If specified by an address, an even address is described.
An SFR that can manipulate one bit can be described in bit manipulation instructions.
•
After Reset ...................... Indicates the state of each register when RESET is input.
