M58LT128HST datasheet(23/110 Pages) STMICROELECTRONICS

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M58LT128HST, M58LT128HSB

Command interface

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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.

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.

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.

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.

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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