M58PR512LE datasheet(37/119 Pages) STMICROELECTRONICS

37 / 119 page

M58PR256LE, M58PR512LE, M58PR001LE

Command interface

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4.25

Unlock EFA Block command

The Unlock EFA Block command unlocks an EFA block, allowing the EFA block to be

programmed or erased.

Two bus write cycles are required to issue the Unlock EFA Block command.

●

The first bus cycle sets up the Unlock EFA Block command.

●

The second bus write cycle latches the block address and unlocks the block.

The lock status can be monitored for each EFA block using the Read Electronic Signature

command.

Refer to Section 12: Block locking for a detailed explanation and to Appendix C, Figure 25:

Main array and EFA locking operations flowchart and pseudocode for a flowchart for using

the Unlock EFA Block command.

4.26

Lock-down EFA Block command

The Lock-down EFA Block command is used to lock down a locked or unlocked EFA block.

A locked-down EFA block cannot be programmed or erased. The lock status of a locked-

down EFA block cannot be changed when WP is Low, VIL. When WP is High, VIH, the lock-

down function is disabled and the locked EFA blocks can be individually unlocked by issuing

the Unlock EFA Block command.

Two bus write cycles are required to issue the Lock-down EFA Block command.

●

The first bus cycle sets up the Lock-down EFA Block command.

●

The second bus write cycle latches the block address and locks down the block.

The lock status can be monitored for each EFA block using the Read Electronic Signature

command.

Locked-down EFA blocks revert to the locked (and not locked-down) state when the device

is reset on power-down. Table 22 shows the lock status after issuing a Lock-down EFA Block

command.

Refer to Section 12: Block locking for a detailed explanation and to Appendix C, Figure 25:

Main array and EFA locking operations flowchart and pseudocode for a flowchart for using

the Lock-down EFA Block command.

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