M29DW128F60NF1F datasheet(23/93 Pages) STMICROELECTRONICS

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M29DW128F

5 Software Protection

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Software Protection

The M29DW128F has two different Software Protection modes: the Standard Protection mode

and the Password Protection mode.

On first use all parts default to the Standard Protection mode and the customer is free to

activate the Standard or the Password Protection mode.

The desired protection mode is activated by setting one of two one-time programmable bits, the

Standard Protection Mode Lock bit or the Password Protection Mode Lock bit. Programming

the Standard and the Password Protection Mode Lock bit to ‘1’ will permanently activate the

Standard Protection mode and the Password Protection mode, respectively. These two bits are

one-time programmable and non-volatile, once the Protection mode has been programmed, it

cannot be changed and the device will permanently operate in the selected Protection mode. It

is recommended to activate the desired Software Protection mode when first programming the

device.

The device is shipped with all blocks unprotected. The Block Protection Status can be read by

issuing the Auto Select command (see Table 10: Block Protection Status).

The Standard and Password Protection modes offer two levels of protection, a Block Lock/

Unlock protection and a Non-Volatile protection.

For the four outermost parameter blocks, an even higher level of block protection can be

achieved by locking the blocks using the Non-Volatile Protection and then by holding the VPP/

WP pin Low.

5.1

Standard Protection Mode

5.1.1

Block Lock/Unlock Protection

It is a flexible mechanism to protect/unprotect a block or a group of blocks from program or

erase operations.

A volatile Lock bit is assigned to each block or group of blocks. When the lock bit is set to ‘1’ the

associated block or group of blocks is protected from program/erase operations, when the Lock

bit is set to ‘0’ the associated block or group of blocks is unprotected and can be programmed

or erased.

The Lock bits can be set (‘1’) and cleared (‘0’) individually as often as required by issuing a Set

Lock Bit command and Clear Lock bit command, respectively.

After a Power-up or Hardware Reset, all the Lock bits are cleared to ‘0’ (block unlocked).

5.1.2

Non-Volatile Protection

A Non-Volatile Modify Protection bit is assigned to each block or group of blocks.

When a Non-Volatile Modify Protection bit is set to ‘1’ the associated block or group of blocks is

protected, preventing any program or erase operations in this block or group of blocks.

The Non-Volatile Modify Protection bits are set individually by issuing a Set Non-Volatile Modify

Protection Bit command. They are non-volatile and will remain set through a hardware reset or

a power-down/power-up sequence.

M29DW128F60NF1F Datasheet(PDF) 23 Page - STMicroelectronics

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