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AS8F128K32

Austin Semiconductor, Inc.

AS8F128K32

Rev. 2.0 5/03

Austin Semiconductor, Inc. reserves the right to change products or specifications without notice.

6

COMMAND DEFINITIONS

Writing specific address and data commands or sequences

into the command register initiates device operations. The

Command Definitions table defines the valid register command

sequences. Writing incorrect address and data values or

writing them in the improper sequence resets the device to

reading array data.

All addresses are latched on the falling edge of WEx\ or

CEx\, whichever happens later. All data is latched on the rising

edge of WEx\ or CEx\, whichever happens first. Refer to the

appropriate timing diagrams in the “AC Characteristics”

section.

Reading Array Data

The device is automatically set to reading array data after

device power-up. No commands are required to retrieve data.

The device is also ready to read array data after completing an

Embedded Program or Embedded Erase algorithm.

The system must issue the reset command to re-enable the

device for reading array data if I/O5* goes high, or while in the

autoselect mode. See the “Reset Command” section, next.

See also “Requirements for Reading Array Data” in the

“Device Bus Operations” section for more information. The

Read Operations table provides the read parameters, and Read

Operation Timings diagram shows the timing diagram.

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. 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.

If I/O5* goes high during a program or erase operation,

writing the reset command returns the device to reading array

data.

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 method is an alternative to that shown in the Autoselect

Codes (High Voltage Method) table, which is intended for

PROM programmers and requires V

The autoselect command sequence is initiated by writing

two unlock cycles, followed by the autoselect command. The

device then enters the autoselect mode, and the system may

read at any address any number of times, without initiating

another command sequence.

A read cycle at address XX00h or retrieves the

manufacturer code. A read cycle at address XX01h returns the

device code. A read cycle containing a sector address (SA) and

the address 02h in returns 01h if that sector is protected, or 00h

if it is unprotected. Refer to the Sector Address tables for valid

sector addresses.

The system must write the reset command to exit the

autoselect mode and return to reading array data.

Byte Program Command Sequence

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 verify the

programmed cell margin. The Command Definitions take 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 I/O7or I/O6. 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 I/O5* 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”.