ST10F269ZX datasheet(21/184 Pages) STMICROELECTRONICS

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ST10F269

5 - INTERNAL FLASH MEMORY

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5.3.5 - Flash Protection Register

The Flash 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 programmed by using the dedi-

cated Set Protection command.

Flash Protection Register (PR)

*Not avalaible for 128K versions (reserved areas)

5.3.6 - Instructions Description

Twelve instructions dedicated to Flash memory

accesses are defined as follow:

Read/Reset (RD). The Read/Reset instruction

consist of one write cycle with data XXF0h. it can

be optionally preceded by two CI enable coded

cycles (data xxA8h at address 1554h + data

xx54h at address 2AA8h). Any successive read

cycle following a Read/Reset instruction will read

the memory array. A Wait cycle of 10µs is

necessary after a Read/Reset command if the

memory was in program or Erase mode.

Program Word (PW). This instruction uses four

write cycles. After the two Cl enable coded cycles,

the Program Word command xxA0h is written at

address 1554h. The following write cycle will latch

the address and data of the word to

programmed. Memory programming can be done

only by writing 0's instead of 1's, otherwise an

error occurs. During programming, the Flash

Status is checked by reading the Flash Status bit

FSB.2, FSB.5, FSB.6 and FSB.7 which show the

status of the EPC. FSB.2, FSB.6 and FSB.7

determine if programming is on going or has

completed, and FSB.5 allows a check to be made

for any possible error.

Block Erase (BE). This instruction uses a

minimum of six command cycles. The erase

enable command xx80h is written at address

1554h after the two-cycle CI enable sequence.

The erase confirm code xx30h must be written at

an address related to the block to be erased

preceded by the execution of a second CI enable

sequence. Additional erase confirm codes must

be given to erase more than one block in parallel.

Additional erase confirm commands must be

written within a defined time-out period. The input

of a new Block Erase command will restart the

time-out period.

When this time-out period has elapsed, the erase

starts. The status of the internal timer can be

monitored through the level of FSB.3, if FSB.3 is

‘0’, the Block Erase command has been given and

BP6*

BP5*

BP4

BP3

BP2

BP1

BP0

BPx

Block x Protection Bit (x = 0...6)

‘0’: the Block Protection is enabled for block x. Programming or erasing the block is not

possible, unless a Block Temporary Unprotection command is issued.

1’: the Block Protection is disabled for block x.

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

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

Block Protection using the Block Temporary Unprotection instruction.

Code Protection Bit

‘0’: the Flash Code Protection is enabled. Read accesses to the Flash for execution not

performed in the Flash itself are not allowed, the returned value will be 009Bh, whatever the

content of the Flash is.

1’: the Flash Code Protection is disabled: read accesses to the Flash from external or internal

RAM are allowed

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

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

Code Protection using the Code Temporary Unprotection instruction.

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