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to another mode, also, a mode programming setup time is necessary with respect to the reset
release timing.
In a reset during operation, the RES pin must be held low for a minimum of 20 system clock
cycles.
• In user program mode, FWE can be switched between high and low level regardless of RES
input.
FWE input can also be switched during execution of a program in flash memory.
• Do not apply FWE if program runaway has occurred.
During FWE application, the program execution state must be monitored using the watchdog
timer or some other means.
• Disconnect FWE only when the SWE, ESU, PSU, EV, PV, E, and P bits in FLMCR are
cleared.
Make sure that the SWE, ESU, PSU, EV, PV, E, and P bits are not set by mistake when
applying or disconnecting FWE.
4. Do not apply a constant high level to the FWE pin
T prevent erroneous programming or erasing due to program runaway, etc., apply a high level to
the FWE pin only when programming or erasing flash memory (including execution of flash
memory emulation using RAM). A system configuration in which a high level is constantly
applied to the FWE pin should be avoided. Also, while a high level is applied to the FWE pin, the
watchdog timer should be activated to prevent overprogramming or overerasing due to program
runaway, etc.
5. Use the recommended algorithm when programming and erasing flash memory.
The recommended algorithm enables programming and erasing to be carried out without
subjecting the device to voltage stress or sacrificing program data reliability. When setting the
PSU or ESU bit in FLMCR, the watchdog timer should be set beforehand as a precaution against
program runaway, etc.
6. Do not set or clear the SWE bit during execution of a program in flash memory.
Clear the SWE bit before executing a program or reading data in flash memory. When the SWE
bit is set, data in flash memory can be rewritten, but flash memory should only be accessed for
verify operations (verification during programming/erasing).
Similarly, when using the RAM emulation function while a high level is being input to the FWE
pin, the SWE bit must be cleared before executing a program or reading data in flash memory.
However, the RAM area overlapping flash memory space can be read and written to regardless of
whether the SWE bit is set or cleared.
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