tmp89fm42 TOSHIBA Semiconductor CORPORATION, tmp89fm42 Datasheet - Page 322

• Manufacturer Part Number: tmp89fm42
• Description: 8 Bit Microcontroller
• Manufacturer: TOSHIBA Semiconductor CORPORATION

21. Flash Memory
RA003
21.2.2 Flash memory area switching (FLSCR1<FAREA>)
be executed. If a memory transfer instruction is used to read or write data, a read or write can be performed
only on the data area. To perform an erase or write on the code area, therefore, part of the code area must be
temporarily switched to the data area. This switching between data and code areas is performed by making the
appropriate FLSCR1<FAREA> setting.
(AREA C1) in the code area is mapped to 0x8000 through 0xFFFF (AREA D1) in the data area.
"0xD5" on FLSCR2<CR1EN>.
cuting the memory transfer instruction on 0x8000 through 0xFFFF (AREA D1) in the data area.
area are mirror areas; these two areas refer to the same physical address in memory. Therefore, an erase or write
must be performed on one of these two mirror areas. For example, If a write is performed on 0x8000 in the data
area with FLSCR1<FAREA> set to "10" after performing a write on 0x8000 in the data area with
FLSCR1<FAREA> set to "00", data is overwritten. To write data to the flash memory that already has data writ-
ten to it, existing data must first be erased from the flash memory by performing a sector erase or chip erase, and
then data must be written.
or specifying such an area by using jump or call instructions.
To perform an erase or write on the flash memory, a memory transfer instruction (command sequence) must
By setting "0xD5" on FLSCR2<CR1EN> after setting FLSCR1<FAREA> to "10", 0x8000 through 0xFFFF
To restore the flash memory to the initial state of mapping, set FLSCR1<FAREA> to "00", and then set
All flash memory areas can be accessed by performing the appropriate steps described above and then exe-
Additionally, access to areas to which memory is not assigned should be avoided by executing an instruction
0x8000 through 0xFFFF (AREA D1) in the data area and 0x8000 through 0xFFFF (AREA C1) in the code
Figure 21-1 Area Switching Using the FLSCR1<FAREA> Setting
Flash
RAM
RAM
Flash
SFR
SFR
0xFFFF
0x0000
0x0FFF
0x7FFF
0x8000
0x0000
0x0FFF
0x7FFF
0xFFFF
0x8000
Data area
Data area
AREA D1
32768
AREA C1
bytes
32768
bytes
If FLSCR<FAREA> = “00”
If FLSCR<FAREA> = “10”
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Flash
Flash
0x0000
0x7FFF
0xFFFF
0x7FFF
0xFFFF
0x8000
0x0000
0x8000
Code area
Code area
AREA C1
AREA C1
32768
32768
bytes
bytes
TMP89FM42