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CHAPTER 20 1M-BIT (128KB) FLASH MEMORY
20.5 Confirming the Automatic Algorithm Execution State
Because the write/erase flow of the flash memory is controlled using the automatic
algorithm, the flash memory has hardware for posting its internal operating state and
completion of operation. This automatic algorithm enables confirmation of the
operating state of the built-in flash memory using the following hardware sequences.
s Hardware Sequence Flags
The hardware sequence flags are configured from the five-bit output of DQ7, DQ6, DQ5, and
DQ3. The functions of these bits are those of the data polling flag (DQ7), toggle bit flag (DQ6),
timing limit exceeded flag (DQ5), and sector erase timer flag (DQ3). The hardware sequence
flags can therefore be used to confirm that writing or chip sector erase has been completed or
that erase code write is valid.
The hardware sequence flags can be accessed by read-accessing the addresses of the target
sectors in the flash memory after setting of the command sequence (see
Table 20.4-1"Command Sequence Table" in Section
20.4 "Starting the Flash Memory Automatic Algorithm").
Table 20.5-1 "Bit Assignments of Hardware Sequence Flags" lists the bit assignments of the
hardware sequence flags.
To determine whether automatic writing or chip sector erase is being executed, the hardware
sequence flags can be checked or the status can be determined from the RDY bit of the flash
memory control register (FMCS) that indicates whether writing has been completed.
After
writing/erasing has terminated, the state returns to the read/reset state.
When creating a
program, use one of the flags to confirm that automatic writing/erasing has terminated. Then,
perform the next processing operation, such as data read. In addition, the hardware sequence
flags can be used to confirm whether a second or subsequent sector erase code write is valid.
The following sections describe each hardware sequence flag separately.
"Hardware Sequence Flag Functions" lists the functions of the hardware sequence flags.
Table 20.5-1 Bit Assignments of Hardware Sequence Flags
Bit No.
76
543
21
0
Hardware
sequence flag
DQ7
DQ6
DQ5
-
DQ3
-