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2. A RAM area cannot be erased by execution of software in accordance with the erase
algorithm while flash memory emulation in RAM is being used.
3. Block area EB0 includes the vector table. When performing RAM emulation, the
vector table is needed by the overlap RAM.
17.19
Interrupt Handling when Programming/Erasing Flash Memory
All interrupts, including NMI input, are disabled when flash memory is being programmed or
erased (when the P1 or E1 bit is set in FLMCR1, or the P2 or E2 bit is set in FLMCR2), and while
the boot program is executing in boot mode *
There are three reasons for this:
1. Interrupt during programming or erasing might cause a violation of the programming or
erasing algorithm, with the result that normal operation could not be assured.
2. In the interrupt exception handling sequence during programming or erasing, the vector would
not be read correctly *
3. If an interrupt occurred during boot program execution, it would not be possible to execute the
normal boot mode sequence.
For these reasons, in on-board programming mode alone there are conditions for disabling
interrupts, as an exception to the general rule. However, this provision does not guarantee normal
erasing and programming or MCU operation. All requests, including NMI, must therefore be
restricted inside and outside the MCU when programming or erasing flash memory. The NMI
interrupt is also disabled in the error-protection state while the P1 or E1 bit remains set in
FLMCR1, or the P2 or E2 bit remains set in FLMCR2.
Notes: 1. Interrupt requests must be disabled inside and outside the MCU until the programming
control program has completed programming.
2. The vector may not be read correctly in this case for the following two reasons:
•
If flash memory is read while being programmed or erased (while the P1 or E1 bit
is set in FLMCR1, or the P2 or E2 bit is set in FLMCR2), correct read data will not
be obtained (undetermined values will be returned).
•
If the interrupt entry in the vector table has not been programmed yet, interrupt
exception handling will not be executed correctly.
1
, to give priority to the program or erase operation.
2
, possibly resulting in MCU runaway.
Rev. 5.00, 12/03, page 649 of 1088
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