AN2692

Writing code for the ST10F269Zx with 0.35 µm embedded Flash

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2.2.2

Flash memory Status Register

The Flash memory Status Register is described in Section 1.2.3: Same Flash memory

Status Register.

This method of polling the ST10F269Zx embedded Flash memory is recommended and

used in the code examples in this document. There is another method to verify the

completion of a Flash memory operation, it is called the “data polling flow”. It uses the

Toggle bit of the Flash Status Register. The algorithm is described in the figure below.

Figure 1.

Data polling flow

The two read accesses to the Flash memory Status Register must be made consecutively.

The following sequence must be executed:

EXTS

Ra, #1

;use EXTended addressing for next MOV instruction

MOV

Ry, [Rx]

;read Flash Status register (FSB) in Ry

EXTS

Ra, #1 ;use EXTended addressing mode for next MOV instruction

MOV

Rz, [Rx] ;read Flash Status register (FSB) in Rz

Then, the Rz and Ry registers are compared to check the toggling of

the bit.

Start

Read FSB.2, FSB.5, FSB.6 bits

FSB.2, FSB.6

toggle?

FSB.5 = 1?

Read FSB.2, FSB.5, FSB.6 bits

FSB.2, FSB.6

toggle?

Yes

Yes

Yes

No

No

Fail

Pass

No

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