AN2244 datasheet(6/17 Pages) STMICROELECTRONICS

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3 Application example: EEPROM emulation using ST10F27x Flash library

AN2244

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Figure 1.

Variable updates in sector 1

In sector 1, variables are stored until there is insufficient memory space to allocate to one of

these variables (case of variable A in the example).

Assume that the variable A should be updated at the time t

0 + (n+1) * tA with A(t0 + (n+1) * tA).

Addresses from 0x2004 to 0x2FFC are all full, the next value is then stored in the base

address of the space allocated to the variable A in the sector 2.

The latest stored value of every other variable (B and C) is transferred from its last location

in sector 1 to the base address of its allocated space in sector 2.

This is illustrated in the Figure 2.

A( t0 )

A(t0 + tA)

A(t0 + 2 * tA)

A(t0 + 3 * tA)

A(t0 + n * tA)

.......

sector 1 header

sector 2 header

B( t1 )

B(t1 + tB)

B(t1 + 2* tB)

B(t1 + 3 * tB)

C( t2 )

C(t2 + tC)

0x2000

0x2004

0x3FFF

0x2008

0x200C

0x2010

0x2014

0x3004

0x3008

0x300C

0x3000

0x3010

0x4000

0x5FFF

0x5FEC

0x5000

0x3FEC

0x3FF0

sector 1

sector 2 erased

.......

B(t1 + m * tB)

.......

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