Fujitsu MB90890 writing /erasing of flash memory, substitutes for an external EEPROM, “ ”“ ”

New Products MB90890 Series

memory-integrated microcontrollers, the interruption can take place in response to any interruption factor generated after the write/erase is completed, thus enabling the processing of other programs after the write/erase command is issued. Write/erase operations for flash memories are smoothly and reliably executed while system control is in progress.

Fig. 4 provides the specifications for bank-to-bank transmission of the interruption vector.

The interruption vector is transmitted to the upper bank flash memory to rewrite the flash memory in the lower bank, and vice versa. Thus, interruption-based control is available for rewriting in either bank.

■The software sector-protect function prevents erroneous

writing /erasing of flash memory

In the new series, settable sector-protect bits are assigned

to protect individual sectors. An 0 setting in the bit sets

“ ”

the sector-protect function active, thereby protecting the target sector against attempts to perform write/erase

operations. Once 0 is set, the 1 setting (to enable the

“ ”“ ”

Figure 4 Specifications for Bank-to-Bank Transmission of Interruption Vector

write/erase) is disabled until any reset factor can be generated. This ensures that the flash memories are fully protected against write/erase attempts even in the case of program runaway.

■Dual-operation flash memory-integrated microcontroller

substitutes for an external EEPROM

Using the dual-operation flash memory-integrated microcontroller as a substitution for EEPROM offers the following benefits.

●Reduced system board mounting area

The mounting area equivalent to an EEPROM footprint is reduced.

●Available EEPROM-like sector configuration

Eight small-density (4K-byte) sectors are available, providing an easy-to-handle sector configuration for the data-rewrite area (Fig. 4).

●Faster write speed

The targeted write time is 32μs/byte (typical), markedly faster than that with EEPROM.

Available transmission of interruption vector domain

Allowable alternative use for EEPROM		SENbit＝0	Compatible with program updates		SENbit＝1
	Interruption vector domain
	SA9：4K-byte		SA9：4K-byte
	SA8：4K-byte		SA8：4K-byte
	SA7：4K-byte		SA7：4K-byte
	SA6：4K-byte		SA6：4K-byte
	SA5：16K-byte		SA5：16K-byte		Rewriting�
					domain
Upper Bank
	SA4：16K-byte		SA4：16K-byte
Lower Bank	SA3：4K-byte		SA3：4K-byte	Interruption vector domain
	SA2：4K-byte		SA2：4K-byte
		Rewriting�
	SA1：4K-byte		SA1：4K-byte
		domain
	SA0：4K-byte		SA0：4K-byte

14

FIND Vol.21

No.1 2003