AN2244

3 Application example: EEPROM emulation using ST10F27x Flash library

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Figure 3.

Header status switching between sectors 1 and 2

3.4.3

Project routines

EepromFormat( ) routine

This function erases sector 1 and sector 2, and writes a VALID_SECTOR header to sector

1.

WriteVariable( ) routine

This function is called by the user application. It uses WriteVerifyVariableFull( ) and

EepromSectorTransfer( ) routines described later.

See below the procedure of updating a variable entry in the eeprom.

Figure 4.

WriteVariable flowchart

Note:

1

For more informations about Flash error codes, please refer to the "Flash programming for

ST10 devices in 0.18µ technology" application note.

Valid1

Erased2

Valid1

Transfer_

Receive1

Valid2

Valid1

Receive2

Erased1

Valid2

Transfer_

Complete1

Valid2

Complete2

Sector 1 Full

Transfer 1->2 complete

Erase1

Sector 2 Full

Transfer 1->0 complete

Erase2

Write data1

Copy data1->2

Write data2

Copy data2->1

WriteVariable

status = WriteVerifyVariableFull( )

return 0 on success

if status=0x80 (Variable full)

status = EepromSectorTransfer( )

return 0 on success

if status = 0

return Flash error code

on failure.(1)