Fujitsu MB90460 Series, Hardware Manual, Page: 610 / 739

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CHAPTER 23 512K / 1024K BIT FLASH MEMORY
[bit4] RDY (Ready)
This bit is the flash memory write/delete permission bit.
While this bit is "0", the write/delete cannot be executed to the flash memory. Even in this state,
however, suspend commands such as the read/reset command and the sector deletion temporary stop
can be accepted.
0: During the write/delete operation
1: Write/delete operation terminated (Next data write/delete operation permitted)
[bit3, bit1] Reserved bits
These bits are the reserved bits for testing. When these bits are usually used, they must be set to "0".
[bit2, bit0] LPM1, LPM0 (Low-power Mode)
These bits control the current consumption in the flash memory when accessing the flash memory.
However, the access time from the CPU to the flash memory greatly dependent upon the setting.
Therefore, the set values should be selected, depending on the CPU operating frequency.
01: Low-power consumption mode
(Internal operating frequency operating at 4 MHz or less)
10: Low-power consumption mode
(Internal operating frequency operating at 8 MHz or less)
11: Low-power consumption mode
(Internal operating frequency operating at 10 MHz or less)
00: Normal power consumption mode
(Internal operating frequency operating at 12.58 MHz or less)
Note:
The RDYINT bit and RDY bit are not changed simultaneously. Create a program using one of the
RDYINT bit or RDY bit for determination.
RDYINT bit
1 machine cycle
Automatic algorithm
RDY bit
Termination time