Fujitsu MB90480 Series Hardware Manual page 503

[bit5] WE: Write Enable
This bit is a write-enable bit for the flash memory area.
If this bit is "1", a command sequence that targets banks FC to FF (refer to Section "23.4
Method for Starting the Flash Memory's Automatic Algorithm") will result in a write operation
in the flash memory area. If this bit is "0", no write/erase signals are generated. This bit is
used for initiating write/erase commands with respect to the flash memory.
In order to prevent accidental writing of any data to the flash memory, Fujitsu recommends
always setting this bit to "0" whenever no write/erase operations are to be executed.
0
1
[bit4] RDY: ReadDY
This bit is used to allow flash memory write/erase operations to be performed.
If this bit is "0", write/erase operations with respect to the flash memory are not allowed.
However, the command of read/reset and sector erase suspend can be accepted in this
state.
0
1
[bit3] Reserved bit
This bit is reserved. Always set this bit to "0" for ordinary use.
[bit1] Reserved bit
This bit is reserved. Always set this bit to "0" for ordinary use.
[bit2, bit0] LPM1, LPM0: Low Power Mode
These bits are used to control flash memory power consumption. If these bits are set to "00",
flash memory operations are performed normally. If these bits are set to "01", "10" or "11",
however, access to flash memory according to the select signal will be performed in low
power consumption mode. In this case, access time increases significantly compared to
access with LPM = "00", and memory access will be disabled during high-speed operation of
the CPU. To use this mode, use a CPU with a frequency 4 MHz, 8 MHz, or 10 MHz.
LPM1 LPM0
0
0
1
1
Note:
For a CPU operation frequency of 10 MHz or higher, always use normal mode.
Flash memory write/erase prohibited
Flash memory write/erase allowed
Write/erase operation in progress
End of write/erase operation (next data write/erase operation is enabled)
0 Normal power consumption mode
1 Power saving mode (operation with an internal operation frequency of 4MHz)
0 Power saving mode (operation with an internal operation frequency of 8MHz)
1 Power saving mode (operation with an internal operation frequency of 10MHz)
CHAPTER 23 2M/3M BIT FLASH MEMORY
Power consumption mode
481