RL78/G15 CHAPTER 3 CPU ARCHITECTURE
R01UH0959EJ0110 Rev.1.10 Page 62 of 765
Mar 7, 2023
3.2.2 Mirror area
The RL78/G15 mirrors the code flash area of 00800H to 01FFFH, to F0800H to F1FFFH. It also mirrors the data flash
area of 09000H to 093FFH, to F9000H to F93FFH.
By reading data from F0800H to F1FFFH and F9000H to F93FFH, an instruction that does not have the ES register as
an operand can be used, and thus the contents of the code flash can be read with the shorter code. However, the code
flash area is not mirrored to the SFR, extended SFR, RAM, and use prohibited areas.
See 3.2 Memory Space for the mirror area of each product.
The mirror area can only be read and no instruction can be fetched from this area.
The following shows examples.
Example) R5F120x8 (x = 0, 1, 4, 6) (Flash memory: 8 KB, RAM: 1 KB)
Special function register (SFR
)
256 bytes
FFFFFH
00000H
FFF00
H
FFEFFH
FFEE0H
FFEDFH
RAM
1 KB
F0800
H
F07
FFH
Special function register
(2
nd SFR)
2 KB
F0000H
EFFFFH
02000H
01FFFH
FFB
00H
FFAFFH
F2000H
F1FFFH
F9400H
F93FFH
09000H
08
FFFH
09400H
093FFH
Reserved
Reserved
CF mirror
6 KB
Reserved
F
9000H
F
8FFFH
DF mirror
1
KB
Code flash memory
Code flash memory
00800H
007FFH
Mirror
General
-purpose register
32 bytes
For example,
00900H is mirrored to
F0900H
.
Data can therefore be read
by MOV A, !0900H, instead of MOV
ES
, #00H and MOV A, ES:!0900H.
Reserved
Data flash memory
1 KB
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