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17.6.2
Software Protection
Software protection can be implemented by setting the RAMS bit in the RAM control register
(RAMCR) and the erase block register (EBR). With software protection, setting the P or E bit in
the flash memory control register (FLMCR) does not cause a transition to program mode or erase
mode. (See table 17.9.)
Table 17.9
Software Protection
Item
Description
• Setting the RAMS bit 1 in RAMCR places all
Emulation
2
protection*
blocks in the program/erase-protected state.
• Erase protection can be set for individual
Block
specification
blocks by settings in EBR*
protection
protection against programming is disabled.
• Setting EBR to H'00 places all blocks in the
erase-protected state.
Notes: 1. Two modes: program-verify and erase-verify.
2. Excluding a RAM area overlapping flash memory.
3. All blocks are unerasable and block-by-block specification is not possible.
4. When not erasing, set EBR to H'00.
17.6.3
Error Protection
In error protection, an error is detected when MCU runaway occurs during flash memory
programming/erasing*
algorithm, and the program/erase operation is aborted. Aborting the program/erase operation
prevents damage to the flash memory due to overprogramming or overerasing.
If the MCU malfunctions during flash memory programming/erasing, the FLER bit is set to 1 in
the flash memory status register (FLMSR)*
3
EBR settings*
are retained, but program mode or erase mode is aborted at the point at which the
error occurred. Program mode or erase mode cannot be re-entered by re-setting the P or E bit in
FLMCR. However, PV and EV bit setting is enabled, and a transition can be made to verify mode.
Error protection is released only by a RES pin reset, and a WDT reset, or in hardware standby
mode.
Figure 17.13 shows the flash memory state transition diagram.
Notes: 1. This is the state in which the P bit or E bit is set to 1 in FLMCR. Note that NMI input
is disabled in this state. For details see section 17.6.4, NMI Input Disabling Conditions.
504
1
, or operation is not performed in accordance with the program/erase
4
. However,
2
and the error protection state is entered. FLMCR and
Functions
Program
Erase
Not
Not
2
possible*
possible*
—
Not
possible
1
Verify*
Possible
3
Possible
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