Rainbow-electronics DS12887 Manual do Utilizador descarregar pdf (Página 10)

DS12887

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changed. Therefore, the user should avoid interrupt service routines that would cause the time needed to

read valid time/calendar data to exceed 244ms.

The third method uses a periodic interrupt to determine if an update cycle is in progress. The UIP bit in

occur at a rate of greater than t

BUC

allow valid time and date information to be reached at each occurrence

of the periodic interrupt. The reads should be complete within one (t

PI/2

+ t

BUC

) to ensure that data is not

read during the update cycle.

Figure 3. UPDATE-ENDED AND PERIODIC INTERRUPT RELATIONSHIP

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Rainbow-electronics DS12887 Manual do Utilizador Página 10