DocID15687 Rev 5

13/29

PM0059

Flash memory interface

28

Mass Erase

To perform Mass Erase, the following sequence is recommended:

1.

Check that no Flash memory operation is ongoing by checking the BSY bit in the

FLASH_SR register

2.

Set the MER bit in the FLASH_CR register

3.

Set the STRT bit in the FLASH_CR register

4.

Wait for the BSY bit to be cleared

2.5.4

Programming

Standard programming

The Flash memory programming sequence is as follows:

1.

Check that no main Flash memory operation is ongoing by checking the BSY bit in the

FLASH_SR register.

2.

Set the PG bit in the FLASH_CR register

3.

Perform the data write operation(s) to the desired memory address (inside main

memory block or OTP area):

–

Byte access in case of x8 parallelism

–

Half-word access in case of x16 parallelism

–

Word access in case of x32 parallelism

–

Double word access in case of x64 parallelism

4.

Wait for the BSY bit to be cleared

Note:

Successive write operations are possible without the need of an erase operation when

changing bits from ‘1’ to ‘0’.

Writing ‘1’ requires a Flash memory erase operation.

If an erase and a program operation are requested simultaneously, the erase operation is

performed first.

Programming errors

It is not allowed to program data to the Flash memory that would cross the 128-bit row

boundary. In such a case, the write operation is not performed and a program alignment

error flag (PGAERR) is set in the FLASH_SR register.

The write access type (byte, half-word, word or double word) must correspond to the type of

parallelism chosen (x8, x16, x32 or x64). If not, the write operation is not performed and a

program parallelism error flag (PGPERR) is set in the FLASH_SR register.

If the standard programming sequence is not respected (for example, if there is an attempt

to write to a Flash memory address when the PG bit is not set), the operation is aborted and

a program sequence error flag (PGSERR) is set in the FLASH_SR register.

Programming and caches

If a Flash memory write access concerns some data in the data cache, the Flash write

access modifies the data in the Flash memory and the data in the cache.

If an erase operation in Flash memory also concerns data in the data or instruction cache,

you have to make sure that these data are rewritten before they are accessed during code