AT25DF081A-SSH-B Просмотр технического описания (PDF) - Atmel Corporation

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AT25DF081A-SSH-B

8-Mbit 2.7V Minimum Serial Peripheral Interface Serial Flash Memory

Atmel Corporation 

Atmel AT25DF081A

9. Protection Commands and Features

9.1 Write Enable

The Write Enable command is used to set the Write Enable Latch (WEL) bit in the Status Register to a logical “1”

state. The WEL bit must be set before a Byte/Page Program, erase, Protect Sector, Unprotect Sector, Sector Lock-

down, Freeze Sector Lockdown State, Program OTP Security Register, or Write Status Register command can be

executed. This makes the issuance of these commands a two step process, thereby reducing the chances of a

command being accidentally or erroneously executed. If the WEL bit in the Status Register is not set prior to the

issuance of one of these commands, then the command will not be executed.

To issue the Write Enable command, the CS pin must first be asserted and the opcode of 06h must be clocked into

the device. No address bytes need to be clocked into the device, and any data clocked in after the opcode will be

ignored. When the CS pin is deasserted, the WEL bit in the Status Register will be set to a logical “1”. The com-

plete opcode must be clocked into the device before the CS pin is deasserted, and the CS pin must be deasserted

on an even byte boundary (multiples of eight bits); otherwise, the device will abort the operation and the state of the

WEL bit will not change.

Figure 9-1. Write Enable

CS

SCK

SI

SO

01234567

OPCODE

00000110

MSB

HIGH-IMPEDANCE

17

8715B–SFLSH–8/10

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