AT45DB642D datasheet(21/55 Pages) ATMEL

21 / 55 page

3542F–DFLASH–09/06

AT45DB642D

Figure 10-3. Program Security Register

10.2.2

Reading the Security Register

The Security Register can be read by first asserting the CS pin and then clocking in an opcode

of 77H followed by three dummy bytes if using the serial interface and seven dummy bytes if

using the 8-bit interface. After the last don't care bit has been clocked in, the content of the

Security Register can be clocked out on the SO or I/O7 - I/O0 pins. After the last byte of the

Security Register has been read, additional pulses on the SCK/CLK pin will simply result in

undefined data being output on the SO or I/O7 - I/O0 pins.

Deasserting the CS pin will terminate the Read Security Register operation and put the SO or

I/O7 - I/O0 pins into a high-impedance state.

Figure 10-4. Read Security Register

Data Byte

Opcode

Byte 1

Opcode

Byte 2

Opcode

Byte 3

Opcode

Byte 4

Data Byte

n + 1

Data Byte

n + x

Each transition

represents 8 bits

SI or IO

7 - IO0

Opcode

Data Byte

n + 1

Data Byte

n + x

Each transition

represents 8 bits

SI or IO

7 - IO0

SO or IO

7 - IO0

AT45DB642D Datasheet(PDF) 21 Page - ATMEL Corporation

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