UPD784938 Datasheet, PDF (97/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 3 CPU ARCHITECTURE
3.9 Special Function Registers (SFR)
These are registers to which a special function is assigned, such as on-chip peripheral hardware mode registers, control
registers, etc. They are mapped onto the 256-byte space from 0FF00H to 0FFFFH^Note.
Note When the LOCATION 0 instruction is executed. When the LOCATION 0FH instruction is executed, the area is
FFF00H to FFFFFH.
Caution Addresses onto which SFRs are not assigned should not be accessed in this area. If such an address is
as accessed by mistake, the µPD784938 may become deadlocked. A deadlock can only be released by
reset input.
A list of special function registers (SFRs) is given in Table 3-6. The meaning of the items in the table is as explained below.
• Symbol ............................... Symbol that indicates the incorporated SFR. This is a reserved word in the NEC assembler
(RA78K4). With the C compiler (CC78K4), this symbol can be used as an sfr variable by
means of a #pragma sfr command.
• R/W .................................... Indicates whether the corresponding SFR is read/write enabled.
R/W: Read/write enabled
R: Read-only
W: Write-only
• Manipulable Bit Units ......... Indicates the applicable manipulation bit units when the corresponding SFR is manipulated.
A 16-bit-manipulable SFR can be written in the operand “sfrp”, and when specified by an
address, an even address is specified.
A bit-manipulable SFR can be written in a bit manipulation instruction.
• After Reset ......................... Indicates the status of the register after RESET input.
Preliminary User’s Manual U13987EJ1V0UM00
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