P30
Table 30: BEFP Considerations
Parameter/Issue
Requirement
Notes
Cycling
For optimum performance, cycling must be limited below 100 erase cycles per block.
BEFP programs one block at a time; all buffer data must fall within a single block
BEFP cannot be suspended
1
2
Programming blocks
Suspend
Programming the flash
memory array
Programming to the flash memory array can occur only when the buffer is full.
3
Note:
1.
2.
3.
Some degradation in performance may occur if this limit is exceeded, but the internal algorithm continues to work
properly.
If the internal address counter increments beyond the block's maximum address, addressing wraps around to the
beginning of the block.
If the number of words is less than 32, remaining locations must be filled with 0xFFFF.
11.3.2
BEFP Setup Phase
After receiving the BEFP Setup and Confirm command sequence, Status Register bit
SR[7] (Ready) is cleared, indicating that the WSM is busy with BEFP 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 BEFP 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 BEFP 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.
11.3.3
BEFP Program/Verify Phase
After the BEFP 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 BEFP 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 BEFP, 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 BEFP
algorithm will be aborted and the program fails and (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
November 2007
Order Number: 306666-11
Datasheet
59
NUMONYX [ NUMONYX B.V ]
