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11

EN29F800

Rev. E, 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).

Autoselect Command Sequence

The autoselect command sequence allows the host system to access the manufacturer and devices

codes, and determine whether or not a sector is protected. The Command Definitions table shows the

address and data requirements. This is an alternative method which is intended for PROM programmers

Two unlock cycles followed by the autoselect command initiate the autoselect command sequence.

Autoselect mode is then entered and the system may read at any address any number of times, without

needing another command sequence.

The system must write the reset command to exit the autoselect mode and return to reading array data.

Word / Byte Programming Command

The device may be programmed by byte or by word, depending on the state of the Byte# Pin.

Programming the EN29F800 is performed by using a four bus-cycle operation (two unlock write

cycles followed by the Program Setup command and Program Data Write cycle). When the program

command is executed, no additional CPU controls or timings are necessary. An internal timer

bit). When the program operation is successfully completed, the device returns to read mode and

the user can read the data programmed to the device at that address. Note that data can not be

programmed from a 0 to a 1. Only an erase operation can change a data from 0 to 1. When

programming time limit is exceeded, DQ5 will produce a logical “1” and a Reset command can return

the device to Read mode.

Chip Erase Command

Chip erase is a six-bus-cycle operation. The chip erase command sequence is initiated by writing two

unlock cycles, followed by a set-up command. Two additional unlock write cycles are then followed by the

chip erase command, which in turn invokes the Embedded Erase algorithm. The device does

not require

the system to preprogram prior to erase. The Embedded Erase algorithm automatically preprograms and

verifies the entire memory for an all zero data pattern prior to electrical erase. The system is not required

to provide any controls or timings during these operations. The Command Definitions table shows the

address and data requirements for the chip erase command sequence.