AN2678 datasheet(5/16 Pages) STMICROELECTRONICS

No. de pieza	AN2678

Descripción Electrónicos	Extremely accurate timekeeping over

PDF	16 Pages

Scroll/Zoom	100%

Fabricante Electrónico	STMICROELECTRONICS [STMicroelectronics]

Página de inicio	http://www.st.com

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5 / 16 page

AN2678

M41T82-83-93 series RTCs

5/16

Figure 3.

Example timing

1.4

Calculating the period

As shown in Figure 3, the microprocessor will measure multiple cycles of the FT signal to

get a total period, TN. The calculated period of the 512 Hz is then

If N is sufficiently large, the uncertainty error, TεN – Tε1, can be ignored.

The microprocessor's timer will measure the Ti, the period of each sample. Either software

or some other timer function, such as a pulse accumulator, available on many

microprocessor timers, will count the number of samples, N. Likewise TN is the sum of the

Ti, and can be accumulated in a timer function or in software. Once these are determined,

software will then calculate T512 by dividing TN by N.

N cycles

TN=

i=1

FT = 512Hz

ai13997

512

∑

AN2678 Datasheet(PDF) 5 Page - STMicroelectronics