12

Am29F016

Table 5.

Am29F016 Command Definitions

Notes:

1. Bus operations are defined in Table 1.

2. RA = Address of the memory location to be read.

PA = Address of the memory location to be programmed. Addresses are latched on the falling edge of the WE pulse.

SA= Address of the sector to be erased. The combination of A20, A19, A18, A17, and A16 will uniquely select any sector.

3. RD = Data read from location RA during read operation.

PD = Data to be programmed at location PA. Data is latched on the rising edge of WE.

4. Read and Byte program functions to non-erasing sectors are allowed in the Erase Suspend mode.

5. Address bits A15, A14, A13, A12 and A11 = X, X = don’t care.

Read/Reset Command

The read or reset operation is initiated by writing the

read/reset command sequence into the command reg-

ister. Microprocessor read cycles retrieve array data

from the memory. The device remains enabled for

reads until the command register contents are altered.

The device will automatically power-up in the read/

reset state. In this case, a command sequence is not

required to read data. Standard microprocessor read

cycles will retrieve array data. This default value en-

sures that no spurious alteration of the memory content

occurs during the power transition. Refer to the AC

Read Characteristics and Waveforms for the specific

timing parameters.

Autoselect Command

Flash memories are intended for use in applications

where the local CPU can alter memory contents. As

such, ma nufactu re a nd device co de s mu st b e

accessible while the device resides in the target sys-

tem. PROM programmers typically access the signa-

ture codes by raising A9 to a high voltage. However,

multiplexing high voltage onto the address lines is not

generally a desirable system design practice.

The device contains an autoselect command operation

to suppleme nt traditio nal PROM p ro gram min g

methodology. The operation is initiated by writing the

autoselect command sequence into the command reg-

ister. Following the command write, a read cycle from

address XX00H retrieves the manufacturer code of

01H. A read cycle from address XX01H returns the de-

vice code ADH (see Table 2).

All manufacturer and device codes will exhibit odd par-

ity with DQ7 defined as the parity bit.

Furthermore, the write protect status of sectors can be

read in t his m ode. Scann in g the se ct or grou p

addresses (A18, A19, and A20) while (A6, A1, A0) = (0,

1, 0) will produce a logical “1” at device output DQ0 for

a protected sector group.

To terminate the operation, it is necessary to write the

read/reset command sequence into the register.

Byte Programming

The device is programmed on a byte-by-byte basis.

Programming is a four bus cycle operation. There are

two “unlock” write cycles. These are followed by the

program set-up command and data write cycles. Ad-

dresses are latched on the falling edge of CE or WE,

whichever happens later and the data is latched on the

rising edge of CE or WE, whichever happens first. The

rising edge of CE or WE (whichever happens first) be-

gins programming using the Embedded Program Algo-

Command

Sequence

Read/Reset

Bus

Write

Cycles

Req’d

First Bus

Write Cycle

Second Bus

Write Cycle

Third Bus

Write Cycle

Fourth Bus

Read/Write

Cycle

Fifth Bus

Write Cycle

Sixth Bus

Write Cycle

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Reset/Read

1

XXXXH

F0H

Reset/Read

3

5555H

AAH

2AAAH

55H

5555H

F0H

RA

RD

Autoselect

3

5555H

AAH

2AAAH

55H

5555H

90H

Byte Program

4

5555H

AAH

2AAAH

55H

5555H

A0H

PA

Data

Chip Erase

6

5555H

AAH

2AAAH

55H

5555H

80H

5555H

AAH 2AAAH 55H

5555H

10H

Sector Erase

6

5555H

AAH

2AAAH

55H

5555H

80H

5555H

AAH 2AAAH 55H

SA

30H

Erase Suspend

1

XXXXH

B0H

Erase Resume

1

XXXXH

30H