UPD784915B Datasheet, PDF (23/86 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784915B, 784916B
3.3 Special Function Registers (SFRs)
Special function registers are assigned special functions and mapped to a 256-byte space from addresses FF00H
through FFFFH. These registers include mode registers and control registers that control the internal peripheral
hardware units.
Caution Do not access an address to which no SFR is assigned. If such an address is accessed by
mistake, the µPD784916B may be deadlocked. This deadlock can be cleared only by reset input.
Table 3-2 lists the special function registers (SFRs). The meanings of the symbols in this table are as follows:
• Abbreviation ............................ Abbreviation of an SFR. This abbreviation is reserved for NEC’s assembler
(RA78K4). With a C compiler (CC78K4), the abbreviation can be used as an sfr
variable by the #pragma sfr instruction.
• R/W ......................................... Indicates whether the SFR in question can be read or written.
R/W : Read/write
R : Read only
W : Write only
• Bit length ................................. Indicates the bit length (word length) of the SFR.
• Bit units for manipulation ....... Indicates bit units in which the SFR in question can be manipulated. An SFR that
can be manipulated in 16-bit units can be described as the operand sfrp of an
instruction. Specify an even address to manipulate this SFR.
An SFR that can be manipulated in 1-bit units can be described for a bit
manipulation instruction.
• After reset ............................... Indicates the status of each register after the RESET signal has been input.
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