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APPENDIX C 512K-BIT FLASH MEMORY
MB90560 series
[Bit 0]: Low Power Mode (LPM)
When this bit is set to “1”, the "L" period of the CEX signal supplied to flash memory during
access to flash memory is minimized to suppress the power consumption of flash memory.
However, the access time is greatly increased compared with that when LPM is “0”, and memory
access is disabled when the CPU runs in high-speed mode. When LPM mode is used, therefore,
run the CPU at frequencies of 4 MHz or less.
<Check>
The RDYINT and RDY bits do not change simultaneously. Create a program so that it uses
one of them for a decision.
I
Read/Write Access Method
While flash memory mode requires external-pin control for read or write access to the 1M-bit
flash memory, normal mode does not require it because access timing is controlled by the
flash memory interface circuit. The write access explained below is a write access to the
command register to activate the automatic algorithm and means a write to flash memory.
I
Read/Write Access in Flash Memory Mode
Table C-2 lists the pin settings for read, write, and other operations in flash memory mode.
Control of these pin settings is not a problem when connecting to the flash memory writer but
must satisfy the timing specifications of the individual pins in other cases. See the separate
section for the timing specifications. Since data bus width is limited to eight bits in flash
memory mode, fix the BYTEX pin to “0”.
Table C-2 Pin settings for read/write access in flash memory mode
Operation
CEX
OEX
WEX
AQ0~16
DQ0~7
RSTX
Read
L
L
H
Read
address
DOUT
H
Write
L
H
L
Write
address
DIN
H
Output
disable
L
H
H
High-Z
H
Standby
H
High-Z
H
Hardware
reset
High-Z
L
RDY input
RDYINT bit
RDY bit
1 machine cycle