H8SSLASH2224 datasheet(832/1071 Pages) RENESAS

832 / 1071 page

Section 20 Flash Memory (F-ZTAT Version)

Rev. 5.00 Aug 08, 2006 page 746 of 982

REJ09B0054-0500

Do not select the HN27C4096 setting for the PROM programmer, and only use the specified

socket adapter. Failure to observe these points may result in damage to the device.

Powering On and Off (See Figures 20.14 to 20.16): Do not apply a high level to the FWE pin

until VCC has stabilized. Also, drive the FWE pin low before turning off VCC.

When applying or disconnecting VCC power, fix the FWE pin low and place the flash memory in

the hardware protection state.

The power-on and power-off timing requirements should also be satisfied in the event of a power

failure and subsequent recovery.

FWE Application/Disconnection (See Figures 20.14 to 20.16): FWE application should be

carried out when MCU operation is in a stable condition. If MCU operation is not stable, fix the

FWE pin low and set the protection state.

The following points must be observed concerning FWE application and disconnection to prevent

unintentional programming or erasing of flash memory:

• Apply FWE when the VCC voltage has stabilized within its rated voltage range.

• In boot mode, apply and disconnect FWE during a reset.

• 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 E1 bits in FLMCR1

are cleared.

Make sure that the SWE1, ESU1, PSU1, EV1, PV1, P1, and E1 bits are not set by mistake

when applying or disconnecting FWE.

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.

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.

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