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programming or erroneous erasing state at the point of transition to this protection mode, or where
programming or erasing is not properly carried out because of an abort. In cases such as these, a
forced recovery (program rewrite) must be executed using boot mode. However, it may also
happen that boot mode cannot be normally initiated because of overprogramming or overerasing.
15.8.4
NMI Input Disable Conditions
While flash memory is being programed/erased and the boot program is executing in the boot
mode (however, period up to branching to on-chip RAM area)*
the programming/erasing operations have priority.
This is done to avoid the following operation states:
1. Generation of an NMI input during programming/erasing violates the program/erase
algorithms and normal operation can not longer be assured.
2. Vector-read cannot be carried out normally*
programming/erasing and the microcomputer runs away as a result.
3. If an NMI input is generated during boot program execution, the normal boot mode sequence
cannot be executed.
Therefore, this LSI has conditions that exceptionally disable NMI inputs only in the on-board
programming mode. However, this does not assure normal programming/erasing and
microcomputer operation.
Thus, when programming or erasing flash memory, all interrupt requests inside and outside the
microcomputer, including NMI, must be restricted. NMI inputs are also disabled in the error
protection state and the state that holds the P or E bit in FLMCR during flash memory emulation
by RAM.
Notes: 1. Indicates the period up to branching to the on-chip RAM boot program area. (This
branch occurs immediately after user program transfer was completed.)
Therefore, after branching to RAM area, NMI input is enabled in states other than the
program/erase state. Thus, interrupt requests inside and outside the microcomputer
must be disabled until initial writing by user program (writing of vector table and NMI
processing program, etc.) is completed.
2. In this case, vector read is not performed normally for the following two reasons:
a. The correct value cannot be read even by reading the flash memory during
programming/erasing. (Value is undefined.)
b. If a value has not yet been written to the NMI vector table, NMI exception handling
will not be performed correctly.
1
, NMI input is disabled because
2
during NMI exception handling during
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