18.8 Flash Memory Emulation by RAM
Erasing and programming flash memory takes time, which can make it difficult to tune parameters
and other data in real time. If necessary, real-time updates of flash memory can be emulated by
overlapping the small-block flash-memory area with part of the RAM (H'FFF000 to H'FFF1FF).
This RAM reassignment is performed using bits 3 to 0 of the RAM control register (RAMCR).
After a flash memory area has been overlapped by RAM, it can be accessed from two address
areas: the overlapped flash memory area, and the original RAM area (H'FFF000 to H'FFF1FF).
Table 18-16 indicates how to reassign RAM.
RAM Control Register (RAMCR)
Note:
*
Bit 7 and bits 3 to 0 are initialized by a reset and in hardware standby mode. They are
not initialized in software standby mode.
Table 18-16 RAM Area Reassignment
Bit 3
Bit 2
Bit 1
Bit 0
RAM Area
RAMS
RAM2
RAM1
RAM0
H'FFF000 to H'FFF1FF
0
0/1
0/1
0/1
H'01F000 to H'01F1FF
1
0
0
0
H'01F200 to H'01F3FF
1
0
0
1
H'01F400 to H'01F5FF
1
0
1
0
H'01F600 to H'01F7FF
1
0
1
1
H'01F800 to H'01F9FF
1
1
0
0
H'01FA00 to H'01FBFF
1
1
0
1
H'01FC00 to H'01FDFF
1
1
1
0
H'01FE00 to H'01FFFF
1
1
1
1
Bit
Initial value
R/W
7
0
FLER
RAMS
6
5
4
3
2
1
0
1
1
0
0
0
0
R
—
—
—
R/W
R/W
R/W
R/W
—
—
—
RAM2
RAM1
RAM0
*
1
611
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