3 Application example: EEPROM emulation using ST10F27x Flash library

AN2244

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Figure 7.

EepromSectorTransfer flowchart

FindValidSector( ) routine

This function reads both sector headers and returns the sector number which contains valid

data. It has as parameter a byte indicating that we are looking for a valid sector for write or

read operation( READ_FROM_VALID_SECTOR or WRITE_IN_VALID_SECTOR).

The following diagram describes this routine principle.

Figure 8.

Find_Valid_sector flowchart

FlashRead( ) routine

This routine allows 32-bit data to be read from a given Flash address.

Write new sector header

RECEIVE DATA

Transfer Data to new sector

Mark old sector TRANSFER

COMPLETE

Mark new sector VALID

Erase old sector

( including the new one)

sector

Switch operation

Write

Read

sector 1

status

=valid ?

status

=receive data?

sector 2

Yes

Return sector 2

Yes

Return sector 1

No

status

=valid?

sector 2

No

status

= receive data?

sector 1

Return sector 1

Yes

Return sector 2

No

Yes

sector 1

status

=valid ?

Yes

Return sector 1

No

sector 2

status

=valid?

Return sector 2

Yes

Find_Valid_Sector(operation)

No

Return No_Valid_Sector

Return No_Valid_Sector

No