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MB95630H Series
25.6
Operations
Pay attention in particular to the following points when using dual operation
Flash memory:
• Interrupt generated when upper banks are updated
• Procedure of setting the sector swap enable bit in the flash memory status
register (FSR:SSEN)
■ Interrupt Generated When Upper Banks Are Updated
The dual operation Flash memory consists of two banks. Like conventional Flash products,
however, it cannot be erased/programmed and read at the same time in banks on the same side.
As SA2 contains an interrupt vector, an interrupt vector from the CPU cannot be read normally
when an interrupt occurs during programming data to an upper bank. Before an upper bank can
be updated, the sector swap enable bit must be set to "1" (FSR:SSEN = 1). When an interrupt
occurs, therefore, SA1 is accessed to read interrupt vector data. The same data must be copied
to SA1 and SA2 before the sector swap enable bit (FSR:SSEN) is set.
■ Procedure for Setting Sector Swap Enable Bit (FSR:SSEN)
Figure 25.6-1 shows a sample procedure of setting the sector swap enable bit (FSR:SSEN).
To modify data in the upper bank, it is necessary to set FSR:SSEN to "1". While data is being
written to the Flash memory, modifying the setting of FSR:SSEN is prohibited. The setting of
FSR:SSEN can only be modified before the start of programming data to the Flash memory or
after the completion of programming data to the Flash memory. In addition, control the Flash
memory interrupts while setting FSR:SSEN as follows: before setting FSR:SSEN, disable the
Flash memory interrupts; after setting FSR:SSEN, enable the interrupts.
Figure 25.6-1 Sample Procedure for Setting the Sector Swap Enable Bit (FSR:SSEN)
Update data in lower bank
MN702-00009-1v0-E
Start updating Flash data
Start program operation
Complete
Flash data update
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER 25 DUAL OPERATION FLASH MEMORY
Update data in upper bank
Copy data
from SA2 to SA1
Set FSR:SSEN to "1"
Start program operation
Complete
Flash data update
Set FSR:SSEN to "0"
25.6 Operations
555
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