256Mb: 3V Embedded Parallel NOR Flash
READ and AUTO SELECT Operations
READ and AUTO SELECT Operations
READ/RESET Command
The device is in read mode after a reset or power-up. The READ/RESET (F0h) command
returns the device to read mode and resets the errors in the status register. One or three
bus WRITE operations can be used to issue the READ/RESET command.
To return the device to read mode, this command can be issued between bus WRITE
cycles before the start of a PROGRAM or ERASE operation. If the READ/RESET com-
mand is issued during the timeout of a BLOCK ERASE operation, the device requires up
to 10μs to abort, during which time no valid data can be read.
The READ/RESET command will not abort a PROGRAM operation if executed while the
device is in program suspend, or an ERASE operation if executed while the device is in
erase suspend.
READ CFI Command
The READ CFI (98h) command puts the device in read CFI mode and is only valid when
the device is in read array or auto select mode. One bus WRITE cycle is required to issue
the command.
Once in read CFI mode, bus READ operations will output data from the CFI memory
area (Refer to the Common Flash Interface for details). A READ/RESET command must
be issued to return the device to the previous mode (read array or auto select ). A sec-
ond READ/RESET command is required to put the device in read array mode from auto
select mode.
UNLOCK BYPASS READ CFI Command
The UNLOCK BYPASS READ CFI (98h) command enables the device to read the CFI
when the device is in the unlock bypass mode.
Once in read CFI mode, bus READ operations will output data from the CFI memory
area (Refer to the Common Flash Interface for details). A READ/RESET command must
be issued to return the device to the previous mode (read array or auto select ). A sec-
ond READ/RESET command is required to put the device in read array mode from auto
select mode.
AUTO SELECT Command
At power-up or after a hardware reset, the device is in read mode. It can then be put in
auto select mode by issuing an AUTO SELECT (90h) command. Auto select mode ena-
bles the following device information to be read:
• Electronic signature, which includes manufacturer and device code information as
shown in the Electronic Signature tables.
• Block protection, which includes the block protection status and extended memory
block protection indicator, as shown in the Block Protection tables.
For example, auto select mode can be used by the programming equipment to auto-
matically match a device with the application code to be programmed.
Electronic signature or block protection information is read by executing a READ opera-
tion with control signals and addresses set, as shown in the Read Electronic Signature
PDF: 09005aef84ecabef
m29dw_256g.pdf - Rev. A 10/12 EN
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