3 Application example: EEPROM emulation using ST10F27x Flash library

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3.4

EEPROM software description

This section describes the software implemented for EEPROM emulation using the

ST10F27x Flash library provided by STMicroelectronics.

This example uses the 3 variables A, B and C already defined.

The project contains 3 source files in addition to the three library source files:

●

eeprom.c: containing C code for the following project routines

EepromFormat( )

WriteVariable( )

ReadVariable( )

FindValidSector( )

WriteVerifyVariableFull( )

EepromSectorTransfer( )

FlashRead( )

●

eeprom.h: containing the routines’ prototypes and some declarations.

●

main.c: This application program is an example that uses the routines described in

eeprom.c in order to write and read from the eeprom.

3.4.1

Header field

The header field occupies each sector base address and gives the sector’s status

information. Each sector has four possible states:

●

ERASED: This sector is empty.

●

RECEIVE_DATA: This sector is receiving data from the full one.

●

VALID_SECTOR: This sector contains valid data and this state will not change until

valid data are completely transferred to the erased sector.

●

TRANSFER_COMPLETE: Transfer of data to the other sector is finished and this

sector is no longer in use. The system can then erase this sector to prepare it for future

data.

The Figure 3 shows how to switch from one state to another for both sectors.

3.4.2

Variables array

Every variable is defined by its start address in its allocated memory space.

An array of variables is declared and located in the user application as described in

Section 3.4.4

Its size must be defined in the eeprom.h file.