Introduction to ST10F269Zx 0.35 µm embedded Flash memory

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1.2.4

Boot block architecture

The ST10F269Zx with a 0.35 µm embedded Flash memory has the same boot blocks as

the M29F400 standalone Flash memory: 4 boot blocks (16 Kbyte, then 8 Kbyte, 8 Kbyte and

32 Kbyte).

1.2.5

Protection

Compared to standalone Flash memories, the ST10F269Zx with an embedded Flash

memory provides 2 different protections:

●

Block protection, as already implemented on ST standalone Flash memories, protects

each block against inadvertent erasing,

●

Code protection, is a set of new commands to protect the proprietary code written in

the Flash memory: code protection disables data operand accesses and program

branches from any location outside the embedded Flash memory.

The different protections are controlled through the Flash memory Protection Register. It is

identical to the one of standalone Flash memories except for the code protection.

The Flash memory Protection Register is a non-volatile register that contains the protection

status. This register can be read by using the Read Protection Status (RP) command, and

Flash memory Protection Register (PR)

FSB.2 bit Flash Status Bit 2: Toggle bit

This toggle bit, together with FSB.6, can be used to determine the chip status during the Erase or

Erase Suspend mode. It can also be used to identify the block being Erase-Suspended. A Read

operation will cause FSB.2 to Toggle during the Erase mode. If the Flash memory is in Erase

Suspend mode, a read operation from the Erase-Suspended block or a program operation into the

Erase-Suspended block will cause FSB.2 to toggle.

When the Flash memory is in program mode during Erase Suspend, FSB.2 will be read as ‘1’ if

address used is the address of the word being programmed.

After Erase completion with an error status, FSB.2 will toggle when reading the faulty sector.

15

14

13

12

11

10

9876543210

CP

BP6

BP5

BP4

BP3.3

BP2.2

BP1

BP0

BPx bits Block x Protection bit (x = 0...10)

‘0’: block protection is enabled for block x. Programming or erasing the block is not possible, unless

a Block Temporary Unprotection command is issued.

1’: block protection is disabled for block x.

Bit is ‘1’ by default, and can be permanently programmed to ‘0’ using the Set Block Protection

command but then cannot be set to ‘1’ again. It is therefore possible to temporarily disable the block

protection using the Block Temporary Unprotection command.