M58LT128HST Datasheet, PDF (23/110 Pages) STMicroelectronics – 128-Mbit (8 Mb ×16, Multiple Bank, Multilevel interface, Burst) 1.8 V supply, Secure Flash memories

M58LT128HST, M58LT128HSB
Command interface
4.9
Buffer Program command
The Buffer Program Command makes use of the device’s 32-word Write Buffer to speed up
programming. Up to 32 words can be loaded into the Write Buffer. The Buffer Program
command dramatically reduces in-system programming time compared to the standard non-
buffered Program command.
Four successive steps are required to issue the Buffer Program command.
1. The first Bus Write cycle sets up the Buffer Program command. The setup code can be
addressed to any location within the targeted block.
After the first Bus Write cycle, read operations in the bank will output the contents of the
Status Register. Status Register bit SR7 should be read to check that the buffer is available
(SR7 = 1). If the buffer is not available (SR7 = 0), re-issue the Buffer Program command to
update the Status Register contents.
2. The second Bus Write cycle sets up the number of words to be programmed. Value n is
written to the same block address, where n+1 is the number of words to be
programmed.
3. Use n+1 Bus Write cycles to load the address and data for each word into the Write
Buffer. Addresses must lie within the range from the start address to the start address +
n, where the start address is the location of the first data to be programmed. Optimum
performance is obtained when the start address corresponds to a 32 word boundary.
4. The final Bus Write cycle confirms the Buffer Program command and starts the
program operation.
All the addresses used in the Buffer Program operation must lie within the same block.
Invalid address combinations or failing to follow the correct sequence of Bus Write cycles
will set an error in the Status Register and abort the operation without affecting the data in
the memory array.
If the block being programmed is protected an error will be set in the Status Register and the
operation will abort without affecting the data in the memory array.
During Buffer Program operations the bank being programmed will only accept the Read
Array, Read Status Register, Read Electronic Signature, Read CFI Query and the
Program/Erase Suspend command, all other commands will be ignored.
Refer to Dual Operations section for detailed information about simultaneous operations
allowed in banks not being programmed.
See Appendix C, Figure 21: Buffer Program flowchart and pseudo code, for a suggested
flowchart on using the Buffer Program command.
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