M29DW128F datasheet(36/94 Pages) STMICROELECTRONICS

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Command interface

M29DW128F

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6.2.1

Write to Buffer and Program command

The Write to Buffer and Program Command makes use of the device’s 64-byte Write Buffer

to speed up programming. 32 Words/64 bytes can be loaded into the Write Buffer. Each

Write Buffer has the same A5-A22 addresses.The Write to Buffer and Program command

dramatically reduces system programming time compared to the standard non-buffered

Program command.

When issuing a Write to Buffer and Program command, the VPP/WP pin can be either held

High, VIH or raised to VPPH.

See Table 18 for details on typical Write to Buffer and Program times in both cases.

Five successive steps are required to issue the Write to Buffer and Program command:

The Write to Buffer and Program command starts with two unlock cycles.

The third Bus Write cycle sets up the Write to Buffer and Program command. The setup

code can be addressed to any location within the targeted block.

The 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. N+1 must not exceed the size of the Write Buffer or the operation

will abort.

The fifth cycle loads the first address and data to be programmed.

Use N Bus Write cycles to load the address and data for each Word/bytes into the

Write Buffer. Addresses must lie within the range from the start address+1 to the start

address + N-1. Optimum performance is obtained when the start address corresponds

to a 64 byte boundary. If the start address is not aligned to a 64 byte boundary, the total

programming time is doubled.

All the addresses used in the Write to Buffer and Program operation must lie within the

same page.

To program the content of the Write Buffer, this command must be followed by a Write to

Buffer and Program Confirm command.

If an address is written several times during a Write to Buffer and 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 failing to follow the correct sequence of Bus Write cycles

will abort the Write to Buffer and Program.

The Status Register bits DQ1, DQ5, DQ6, DQ7 can be used to monitor the device status

during a Write to Buffer and Program operation.

If is not possible to detect Program operation fails when changing programmed data from ‘0’

to ‘1’, that is when reprogramming data in a portion of memory already programmed. The

resulting data will be the logical OR between the previous value and the current value.

A Write to Buffer and Program Abort and Reset command must be issued to abort the Write

to Buffer and Program operation and reset the device in Read mode.

During Write to Buffer and Program operations, the bank being programmed will accept

Program/Erase Suspend commands.

See Appendix E, Figure 27: Write to Buffer and Program flowchart and Pseudo Code, for a

suggested flowchart on using the Write to Buffer and Program command.

M29DW128F Datasheet(PDF) 36 Page - STMicroelectronics

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