28F640L30, 28F128L30, 28F256L30
• Read operation while performing Buffered EFP is not supported.
NOTES:
1. Word buffer boundaries in the array are determined by A[4:0] (0x00 through 0x1F). The alignment start point
is A[4:0] = 0x00.
2. Some degradation in performance may occur if this limit is exceeded, but the internal algorithm continues to
work properly.
3. If the internal address counter increments beyond the block's maximum address, addressing wraps around to
the beginning of the block.
4. If the number of words is less than 32, remaining locations must be filled with 0xFFFF.
5.3.2
Buffered EFP Setup Phase
After receiving the Buffered EFP Setup and Confirm command sequence, Status Register bit SR[7]
(Ready) is cleared, indicating that the WSM is busy with Buffered EFP algorithm startup. A delay
before checking SR[7] is required to allow the WSM enough time to perform all of its setups and
checks (Block-Lock status, VPP level, etc.). If an error is detected, SR[4] is set and Buffered EFP
operation terminates. If the block was found to be locked, SR[1] is also set. SR[3] is set if the error
occurred due to an incorrect VPP level.
Note: Reading from the device after the Buffered EFP Setup and Confirm command sequence outputs
Status Register data. Do not issue the Read Status Register command; it will be interpreted as data
to be loaded into the buffer.
5.3.3
Buffered EFP Program/Verify Phase
After the Buffered EFP Setup Phase has completed, the host programming system must check
SR[7,0] to determine the availability of the write buffer for data streaming. SR[7] cleared indicates
the device is busy and the Buffered EFP program/verify phase is activated. SR[0] indicates the
write buffer is available.
Two basic sequences repeat in this phase: loading of the write buffer, followed by buffer data
programming to the array. For Buffered EFP, the count value for buffer loading is always the
maximum buffer size of 32 words. During the buffer-loading sequence, data is stored to sequential
buffer locations starting at address 0x00. Programming of the buffer contents to the flash memory
array starts as soon as the buffer is full. If the number of words is less than 32, the remaining buffer
locations must be filled with 0xFFFF.
Caution: The buffer must be completely filled for programming to occur. Supplying an address outside of the
current block's range during a buffer-fill sequence causes the algorithm to exit immediately. Any
data previously loaded into the buffer during the fill cycle is not programmed into the array.
The starting address for data entry must be buffer size aligned, if not the Buffered EFP algorithm
will be aborted and the program fail (SR[4]) flag will be set.
Data words from the write buffer are directed to sequential memory locations in the flash memory
array; programming continues from where the previous buffer sequence ended. The host
programming system must poll SR[0] to determine when the buffer program sequence completes.
SR[0] cleared indicates that all buffer data has been transferred to the flash array; SR[0] set
indicates that the buffer is not available yet for the next fill cycle. The host system may check full
status for errors at any time, but it is only necessary on a block basis after Buffered EFP exit. After
the buffer fill cycle, no write cycles should be issued to the device until SR.0 = 0 and the device is
ready for the next buffer fill.
Datasheet
33
INTEL [ INTEL ]
