Command Interface
M29W640GH, M29W640GL, M29W640GT, M29W640GB
The Write Buffer Programming Sequence can be aborted in the following ways:
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Load a value that is greater than the page buffer size during the Number of Locations to
Program step.
Write to an address in a block different than the one specified during the Write-Buffer-
Load command.
Write an Address/Data pair to a different write-buffer-page than the one selected by the
Starting Address during the write buffer data loading stage of the operation.
Write data other than the Confirm Command after the specified number of data load
cycles.
The abort condition is indicated by DQ1 = 1, DQ7 = DATA# (for the last address location
loaded), DQ6 = toggle, and DQ5=0. A Write-to-Buffer-Abort Reset command sequence
must be written to reset the device for the next operation. Note that the full 3-cycle Write-to-
Buffer-Abort Reset command sequence is required when using Write-Buffer-Programming
features in Unlock Bypass mode.
See Appendix E: Flowchart, Figure 29: Write to Buffer and Program flowchart and pseudo
code, for a suggested flowchart on using the Write to Buffer and Program command.
4.2.10
4.2.11
Write to Buffer and Program Confirm command
The Write to Buffer and Program Confirm command is used to confirm a Write to Buffer and
Program command and to program the n+1 words loaded in the Write Buffer by this
command.
Write to Buffer and Program Abort and Reset command
The Write to Buffer and Program Abort and Reset command is used to reset the device after
a Write to Buffer and Program command has been aborted.
4.3
Block Protection commands
4.3.1
Enter Extended Block command
The device has an extra 256 byte block (Extended Block) that can only be accessed using
the Enter Extended Block command. Three Bus write cycles are required to issue the
Extended Block command. Once the command has been issued the device enters
Extended Block mode where all Bus Read or Write operations to the Boot Block addresses
access the Extended Block. The Extended Block (with the same address as the Boot
Blocks) cannot be erased, and can be treated as one-time programmable (OTP) memory. In
Extended Block mode the Boot Blocks are not accessible.
To exit from the Extended Block mode the Exit Extended Block command must be issued.
The Extended Block can be protected, however once protected the protection cannot be
undone.
4.3.2
Exit Extended Block command
The Exit Extended Block command is used to exit from the Extended Block mode and return
the device to Read mode. Four Bus Write operations are required to issue the command.
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