9

1937J–DFLSH–9/05

AT45DB021B

5.4

Operation Mode Summary

The modes described can be separated into two groups – modes which make use of the Flash

memory array (Group A) and modes which do not make use of the Flash memory array (Group

B).

Group A modes consist of:

1.

Main Memory Page Read

2.

Main Memory Page to Buffer 1 (or 2) Transfer

3.

Main Memory Page to Buffer 1 (or 2) Compare

4.

Buffer 1 (or 2) to Main Memory Page Program with Built-in Erase

5.

Buffer 1 (or 2) to Main Memory Page Program without Built-in Erase

6.

Page Erase

7.

Block Erase

8.

Main Memory Page Program through Buffer

9.

Auto Page Rewrite

Group B modes consist of:

1.

Buffer 1 (or 2) Read

2.

Buffer 1 (or 2) Write

3.

Status Register Read

If a Group A mode is in progress (not fully completed), then another mode in Group A should not

be started. However, during this time in which a Group A mode is in progress, modes in Group B

can be started.

This gives the Serial DataFlash the ability to virtually accommodate a continuous data stream.

While data is being programmed into main memory from buffer 1, data can be loaded into buffer

2 (or vice versa). See application note AN-4 (“Using Atmel’s Serial DataFlash”) for more details.

Table 5-3.

Read Commands

Command

SCK Mode

Opcode

Continuous Array Read

Inactive Clock Polarity Low or High

68H

SPI Mode 0 or 3

E8H

Main Memory Page Read

Inactive Clock Polarity Low or High

52H

SPI Mode 0 or 3

D2H

Buffer 1 Read

Inactive Clock Polarity Low or High

54H

SPI Mode 0 or 3

D4H

Buffer 2 Read

Inactive Clock Polarity Low or High

56H

SPI Mode 0 or 3

D6H

Status Register Read

Inactive Clock Polarity Low or High

57H

SPI Mode 0 or 3

D7H