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CHAPTER 17 FLASH MEMORY
17.4.1 Data Polling Flag (DQ7)
The data polling flag uses the data polling function to post that the automatic algorithm
is being executed or has terminated
■ Write
Read-access during execution of the automatic write algorithm causes the flash memory to output the
opposite data of bit7 last written, regardless of the value at the address specified by the address signal.
Read-access at the end of the automatic write algorithm causes the flash memory to output bit7 of the read
value of the address specified by the address signal.
■
Automatic Erasing
Read-access during execution of the automatic erasing algorithm causes the flash memory to output "0",
regardless of the value at the address specified by the address signal. After the automatic erasing algorithm
is executed, "1" is output.
Note:
When the automatic algorithm comes to the end of its operation, bit7 (data polling) changes its state
asynchronously during a read operation. This means that flash memory sends data about the operation
state to bit7 and will then send out fixed data. When flash memory ends the automatic algorithm or even
if bit7 is outputting fixed data, the values of the other bits are still undetermined. Fixed data in the other
bits can be read by successively executing read operations.