H8SLASH3028F datasheet(647/923 Pages) RENESAS

647 / 923 page

Rev. 2.00, 09/03, page 617 of 890

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

If FWE is applied when the MCU’s VCC power supply is not within its rated voltage range,

MCU operation will be unstable and flash memory may be erroneously programmed or

erased.

• Apply FWE when oscillation has stabilized (after the elapse of the oscillation settling

time).

When VCC power is turned on, hold the RES pin low for the duration of the oscillation

settling time before applying FWE. Do not apply FWE when oscillation has stopped or is

unstable.

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

In a transition to boot mode, FWE = 1 input and MD2–MD0 setting should be performed

while the

RES input is low. FWE and MD

2–MD0 pin input must satisfy the mode

programming setup time (tMDS) with respect to the reset release timing. When making a

transition from boot mode 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 FLMCR1 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 FLMCR1, the watchdog timer should be set beforehand as a precaution

against program runaway, etc.

H8/3028F 数据表(PDF) 647 Page - Renesas Technology Corp

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