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M16C/62P Group (M16C/62P, M16C/62PT)
24.14.12 Writing in the user ROM area
EW0 Mode
• If the power supply voltage drops while rewriting any block in which the rewrite control program is
stored, a problem may occur that the rewrite control program is not correctly rewritten and, conse-
quently, the flash memory becomes unable to be rewritten thereafter. In this case, standard serial
I/O or parallel I/O mode should be used.
EW1 Mode
• Avoid rewriting any block in which the rewrite control program is stored.
24.14.13 DMA transfer
In EW1 mode, make sure that no DMA transfers will occur while the FMR00 bit in the FMR0 register = 0
(during the auto program or auto erase period).
24.14.14 Regarding Programming/Erasure Times and Execution Time
As the number of programming/erasure times increases, so does the execution time for software com-
mands (Program, Block Erase, Erase All Unlock Blocks, and Lock Bit Program). Especially when the
number of programming/erasure times exceeds 1,000, the software command execution time is notice-
ably extended. Therefore, the software command wait time that is set must be greater than the maximum
rated value of electrical characteristics.
The software commands are aborted by hardware reset 1, hardware reset 2, NMI interrupt, and watchdog
timer interrupt. If a software command is aborted by such reset or interrupt, the block that was in process
must be erased before reexecuting the aborted command.
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2
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0
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0
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0
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4
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0
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B
0
1
8
5
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2
3
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page 355
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3
6
4
24. Usage Precaution
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