H8SSLASH2214 datasheet(659/936 Pages) RENESAS

659 / 936 page

Section 15 ROM

Rev.4.00 Sep. 18, 2008 Page 599 of 872

REJ09B0189-0400

• In user program mode, FWE can be switched between high and low level regardless of the

reset state. FWE input can also be switched during execution of a program in flash memory.

• Do not apply FWE if program runaway has occurred.

• Disconnect FWE only when the SWE1, ESU1, PSU1, EV1, PV1, P1, and E bits in FLMCR1

are cleared.

Make sure that the SWE1, ESU1, PSU1, EV1, PV1, P1, and E bits are not set by mistake when

applying or disconnecting FWE.

(4) Do not apply a constant high level to the FWE pin

Apply a high level to the FWE pin only when programming or erasing flash memory. 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 P1

or E1 bit in FLMCR1, the watchdog timer should be set beforehand as a precaution against

program runaway, etc.

(6) Do not set or clear the SWE1 bit during execution of a program in flash memory

Wait for at least 100 µs after clearing the SWE1 bit before executing a program or reading data in

flash memory. When the SWE1 bit is set, data in flash memory can be rewritten, but access flash

memory only for verify operations (verification during programming/erasing). Also, do not clear

the SWE1 bit during programming, erasing, or verifying.

Similarly, when using emulation by RAM with a high level applied to the FWE pin, the SWE1 bit

should be cleared before executing a program or reading data in flash memory. However,

read/write accesses can be performed in the RAM area overlapping the flash memory space

regardless of whether the SWE1 bit is set or cleared.

(7) Do not use interrupts while flash memory is being programmed or erased

All interrupt requests, including NMI, should be disabled during FWE1 application to give priority

to program/erase operations.

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