256Mb, 512Mb, 1Gb, 2Gb: 3V Embedded Parallel NOR Flash
Program Operations
First, two UNLOCK cycles are issued. Next, a third bus WRITE cycle sets up the WRITE
TO BUFFER PROGRAM command. The set-up code can be addressed to any location
within the targeted block. Then, a fourth bus WRITE cycle sets up the number of words/
bytes to be programmed. Value n is written to the same block address, where n + 1 is the
number of words/bytes to be programmed. Value n + 1 must not exceed the size of the
program buffer, or the operation will abort. A fifth cycle loads the first address and data
to be programmed. Last, n bus WRITE cycles load the address and data for each word/
byte into the program buffer. Addresses must lie within the range from the start address
+1 to the start address + (n - 1).
Optimum programming performance and lower power usage are achieved by aligning
the starting address at the beginning of a 512-word boundary (A[8:0] = 0x000h). Any
buffer size smaller than 512 words is allowed within a 512-word boundary, while all ad-
dresses used in the operation must lie within the 512-word boundary. In addition, any
crossing boundary buffer program will result in a program abort. For a x8 device, maxi-
mum buffer size is 256 bytes; for a x16 device, the maximum buffer size is 1024 bytes.
To program the content of the program buffer, this command must be followed by a
WRITE TO BUFFER PROGRAM CONFIRM command.
If an address is written several times during a WRITE TO BUFFER PROGRAM operation,
the address/data counter will be decremented at each data load operation, and the data
will be programmed to the last word loaded into the buffer.
Invalid address combinations or the incorrect sequence of bus WRITE cycles will abort
the WRITE TO BUFFER PROGRAM command.
The status register bits DQ1, DQ5, DQ6, DQ7 can be used to monitor the device status
during a WRITE TO BUFFER PROGRAM operation.
The WRITE TO BUFFER PROGRAM command should not be used to change a bit set to
0 back to 1, and an attempt to do so is masked during the operation. Rather than the
WRITE TO BUFFER PROGRAM command, the ERASE command should be used to set
memory bits from 0 to 1.
Figure 9: Boundary Condition of Program Buffer Size
0000h
511 words
or less are
allowed
in the
program
buffer
512-word
program
buffer is
allowed
512 Words
Any
buffer
program
attempt
is not
0200h
allowed
512-word
program
buffer is
allowed
512 Words
0400h
PDF: 09005aef849b4b09
m29ew_256mb_2gb.pdf - Rev. B 8/12 EN
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