Micro Crystal

Real Time Clock / Calendar Module

RV-8564

17/40

9. DETAILED FUNCTIONAL DESCRIPTION

9.1. INTERRUPT OUTPUT

9.1.1.BITS TF AND AF

When an alarm occurs, AF is set to 1. Similarly, at the end of a timer countdown, TF is set to 1. These bits maintain

their value unit overwritten using the interface. If both timer and alarm are required in the application, the source of

the interrupt can be determined by reading these bits. To prevent one flag being overwritten while clearing another,

a logic AND in performed during a write access.

Note:

When bits TIE and AIE are disabled, pin INT will remain high-impedance.

9.1.2.BITS TIE AND AIE

These bits activate or deactivate the generation of an interrupt when TF or AF is asserted respectively. The

interrupt is the logical OR of these two conditions when both AIE and TIE are set.

9.1.3.COUNTDOWN TIMER INTERRUPT

The pulse generator for the countdown timer interrupt uses an internal clock and is dependent on the selected

source clock for the countdown timer and on the countdown value “n”. As a consequence, the width of the interrupt

pulse varies.

INT

operation (bit TI/TP = 1)

1)

Source clock

INT period

n = 1

2)

n > 1

4096 Hz

64 Hz

1 Hz