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M16C/62P Group (M16C/62P, M16C/62PT)
22.3 CPU Rewrite Mode
In CPU rewrite mode, the user ROM area can be rewritten when the CPU executes software commands.
The user ROM area can be rewritten with the microcomputer mounted on a board without using a parallel
or serial programmer.
In CPU rewrite mode, only the user ROM area shown in Figure 22.1 can be rewritten. The boot ROM area
cannot be rewritten. Program and the block erase command are executed only in the user ROM area.
Erase-write 0 (EW0) mode and erase-write 1 (EW1) mode are provided as CPU rewrite mode. Table 22.3
lists differences between erase-write 0 (EW0) and erase-write 1 (EW1) modes.
Table 22.3 EW0 Mode and EW1 Mode
Item
Operation Mode
Space where the rewrite
control program can be
placed
Space where the rewrite
control program can be
executed
Space which can be
rewritten
Software Command
Restriction
Mode after Program or
Erasing
CPU State during Auto
Write and Auto Erase
Flash Memory State
Detection
NOTES:
1. Do not generate an interrupts (except NMI and watchdog timer interrupts) or DMA transfer.
2. When in CPU rewrite mode, the PM10 and PM13 bits in the PM1 register are set to "1". The rewrite control
program can only be executed in the internal RAM or in an external area that is enabled for use when the PM13
bit = 1. When the PM13 bit = 0 and the flash memory is used in 4M-byte mode, the extended accessible area
(40000h to BFFFFh) cannot be used.
R
e
. v
2
3 .
0
S
e
p
0
, 1
2
0
0
4
R
E
J
0
9
B
0
1
8
5
0 -
2
3
0
Z
EW0 Mode
• Single-chip mode
• Memory expansion mode
• Boot mode
• User ROM area
• Boot ROM area
The rewrite control program must be
transferred to any space other than the
flash memory (e.g., RAM) before being
(2)
executed
User ROM area
None
Read status register mode
Operating
• Read the FMR00, FMR06 and FMR07
bits in the FMR0 register by program
• Execute the read status register
command to read the SR7, SR5 and
SR4 bits in the status register.
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22. Flash Memory Version
EW1 Mode
Single-chip mode
User ROM area
The rewrite control program can be
executed in the user ROM area
User ROM area
However, this excludes blocks with the
rewrite control program
• Program and block erase commands
cannot be executed in a block having the
rewrite control program.
• Erase all unlocked block command
cannot be executed when the lock bit in a
block having the rewrite control program
is set to "1" (unlocked) or when the
FMR02 bit in the FMR0 register is set to
"1" (lock bit disabled).
• Read status register command cannot be
used.
Read array mode
Maintains hold state (I/O ports maintains
the state before the command was
(1)
executed)
Read the FMR00, FMR06 and FMR07
bits in the FMR0 register by program
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