UM0116

Read/program the STR7 embedded Flash

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2.3.7

Errors during Write Operation

A complete set of checks is done by the Flash controller after each write operation to verify

that the operation completed successfully.

The FLASH_ER register provides dedicated flags for each error type that might arise during

a write operation as well as a global flag triggered on any error.

The following errors may occur during write operation:

●

Hardware errors:

–

Program Error: this error reports a physical failure of a Flash cell that can no more

be programmed. The word where this error occurred must be rejected.

–

Erase Error: this error reports a physical failure of a Flash cell that can no more be

programmed. The sector where this error occurred must be rejected.

●

Software errors:

–

1 over 0 error: this error reports an attempt to program at ‘1’ a bit, whereas it was

already programmed at ‘0’. The data should be masked with the current value, or

the sector should erased before reprogramming this data.

–

Sequence error: this error reports that an incorrect sequence has been executed

to trigger the write operation. The code applying the sequence should be checked.

–

Resume error: this error reports that a suspend write operation has not been

correctly resumed. The full operation sequence has to be redone.

–

Protection error: this error reports an attempt to write a sector which is write

protected. If the sector effectively needs to be written, the sector should first be

temporary unprotected, then the full operation sequence has to be reexecuted.

2.3.8

Interrupted Write Operation

A failing write operation is normally flagged in the Flash Error Register (FLASH_ER).

Nevertheless, if during a write operation, the internal 1.8V Vdd supply drops below the

internal Flash low voltage detector threshold or if a reset is triggered, the operation is

suddenly interrupted and the Flash controller is reset to Read mode without updating the

FLASH_ER.

The sectors or words that were under modification while the write operation has been

interrupted becomes undefined. The interrupted write operation must be repeated to

recover these resources.