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7

EN29F040

Rev. D, Issue Date: 2001/07/05

Reset Command

Writing the reset command to the device resets the device to reading array data. Address bits are

don’t care for this command.

The reset command may be written between the sequence cycles in an erase command sequence

before erasing begins. This resets the device to reading array data. Once erasure begins, however,

the device ignores reset commands until the operation is complete. The reset command may be

written between the sequence cycles in a program command sequence before programming begins.

This resets the device to reading array data (also applies to programming in Erase Suspend mode).

Once programming begins, however, the device ignores reset commands until the operation is

complete.

The reset command may be written between the sequence cycles in an autoselect command

sequence. Once in the autoselect mode, the reset command must be written to return to reading

array data (also applies to autoselect during Erase Suspend).

If DQ5 goes high during a program or erase operation, writing the reset command returns the device

to reading array data (also applies during Erase Suspend).

Write Mode

Programming is a four-bus-cycle operation. The program command sequence is initiated by writing

two unlock write cycles, followed by the program set-up command. The program address and data

are written next, which in turn initiate the Embedded Program algorithm. The system is not required

to provide further controls or timings. The device automatically provides internally generated program

pulses and verifies the programmed cell margin. Table 5 (Command Definitions) shows the address

and data requirements for the byte program command sequence.

When the Embedded Program algorithm is complete, the device then returns to reading array data

and addresses are no longer latched. The system can determine the status of the program operation

by using DQ7 or DQ6. See “Write Operation Status” for information on these status bits.

Any commands written to the device during the Embedded Program Algorithm are ignored.

Programming is allowed in any sequence and across sector boundaries. A bit cannot be

programmed from a “0” back to a “1”. Attempting to do so may halt the operation and set DQ5 to

“1”, or cause the Data# Polling algorithm to indicate the operation was successful. However, a

succeeding read will show that the data is still “0”. Only erase operations can convert a “0” to a “1”.

COMMAND DEFINITIONS

The operations of the EN29F040 are selected by one or more commands written into the command

register to perform Read/Reset Memory, Read ID, Read Sector Protection, Program, Sector Erase,

Chip Erase, Erase Suspend and Erase Resume. Commands are made up of data sequences

written at specific addresses via the command register. The sequences for the specified operation

are defined in the Command Table (Table 5).

Incorrect addresses, incorrect data values or

improper sequences will reset the device to the read mode.