M29DW128F datasheet(41/93 Pages) STMICROELECTRONICS

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M29DW128F

6 Command Interface

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6.3.13 Verify Non-Volatile Modify Protection Bit command

The status of a Non-Volatile Modify Protection bit for a given block or group of blocks can be

read by issuing a Verify Non-Volatile Modify Protection Bit command along with the block

address.

6.3.14 Clear Non-Volatile Modify Protection Bits command

This command is used to clear all Non-Volatile Modify Protection bits. No specific block address

is required. If the Lock-Down bit is set to ‘1’, the command will fail.

Six cycles are required to issue a Clear Non-Volatile Modify Protection Bits command:

The first two cycles are unlock cycles.

The third cycle issues the command.

The last three cycles verify if the operation has been successful. If DQ0 is set to ’0’, all

Non-Volatile Modify Protection bits have been successfully cleared. If DQ0 is ‘1’, the

operation has failed and the command must be re-issued.

There must be a 12ms delay between the fourth and fifth cycles.

6.3.15 Set Lock Bit command

The Set Lock Bit command individually sets the Lock bit to ‘1’ for a given block or group of

blocks.

If the Non-Volatile Lock bit for the same block or group of blocks is set, the block is locked

regardless of the value of the Lock bit. (see Table 10: Block Protection Status).

6.3.16 Clear Lock Bit command

The Clear Lock Bit command individually clears (sets to ‘0’) the Lock Bit for a given block or

group of blocks.

If the Non-Volatile Lock bit for the same block or group of blocks is set, the block or group of

blocks remains locked (see Table 10: Block Protection Status).

6.3.17 Verify Lock Bit command

The status of a Lock bit for a given block can be read by issuing a Verify Lock Bit command

along with the block address.

6.3.18 Set Lock-Down Bit command

This command is used to set the Lock-Down bit to ‘1’ thus protecting the Non-Volatile Modify

Protection bits from program and erase.

There is no Unprotect Lock-Down Bit command.

6.3.19 Verify Lock-Down Bit command

This command is used to read the status of the Lock-Down bit. The status is output on bit DQ1.

If DQ1 is ‘1’, all the Non-Volatile Modify Protection bits are protected from program or erase

operations.

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