M29W640FT datasheet(20/72 Pages) STMICROELECTRONICS

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4 Command Interface

M29W640FT, M29W640FB

20/72

4.1.3

Read CFI Query command

The Read CFI Query Command is used to read data from the Common Flash Interface (CFI)

Memory Area. This command is valid when the device is in the Read Array mode, or when the

device is in Autoselected mode.

One Bus Write cycle is required to issue the Read CFI Query Command. Once the command is

issued subsequent Bus Read operations read from the Common Flash Interface Memory Area.

The Read/Reset command must be issued to return the device to the previous mode (the Read

Array mode or Autoselected mode). A second Read/Reset command would be needed if the

device is to be put in the Read Array mode from Autoselected mode.

See Appendix B: Common Flash Interface (CFI), Tables 22, 23, 24, 25, 26 and 27 for details on

the information contained in the Common Flash Interface (CFI) memory area.

4.1.4

Chip Erase command

The Chip Erase command can be used to erase the entire chip. Six Bus Write operations are

required to issue the Chip Erase Command and start the Program/Erase Controller.

If any blocks are protected then these are ignored and all the other blocks are erased. If all of

the blocks are protected the Chip Erase operation appears to start but will terminate within

about 100

µs, leaving the data unchanged. No error condition is given when protected blocks

are ignored.

During the erase operation the memory will ignore all commands, including the Erase Suspend

command. It is not possible to issue any command to abort the operation. Typical chip erase

times are given in Table 7: Program, Erase Times and Program, Erase Endurance Cycles. All

Bus Read operations during the Chip Erase operation will output the Status Register on the

Data Inputs/Outputs. See the section on the Status Register for more details.

After the Chip Erase operation has completed the memory will return to the Read Mode, unless

an error has occurred. When an error occurs the memory will continue to output the Status

Read Mode.

The Chip Erase Command sets all of the bits in unprotected blocks of the memory to

’1’. All

previous data is lost.

4.1.5

Block Erase command

The Block Erase command can be used to erase a list of one or more blocks. Six Bus Write

operations are required to select the first block in the list. Each additional block in the list can be

selected by repeating the sixth Bus Write operation using the address of the additional block.

The Block Erase operation starts the Program/Erase Controller about 50

µs after the last Bus

Write operation. Once the Program/Erase Controller starts it is not possible to select any more

blocks. Each additional block must therefore be selected within 50

µs of the last block. The 50µs

timer restarts when an additional block is selected. The Status Register can be read after the

sixth Bus Write operation. See the Status Register section for details on how to identify if the

Program/Erase Controller has started the Block Erase operation.

If any selected blocks are protected then these are ignored and all the other selected blocks are

erased. If all of the selected blocks are protected the Block Erase operation appears to start but

will terminate within about 100

µs, leaving the data unchanged. No error condition is given when

protected blocks are ignored.

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