ACT5880
Rev 2, 03-Sep-13
To clear the RTC wake-up alarm interrupt:
Set bit nWKALM[ ] = 1 ;
Read byte 0x3C;
Read byte 0x3D.
To disable the RTC wake-up alarm:
Set bit nWKALM[ ] = 1;
Set bit RAAI[ ] = 0.
And every change interrupt is also available in the
ACT5880, enabled by setting respective register bits
of the RDAI[ ], RHAI[ ], RMAI[ ] and RSAI[ ]. This
functions helps in maintaining the clock display
refresh against the day counts changes, the hour
counts changes, the minute counts changes and the
second counts changes. When the every change
happens, the interrupt output is kept for 0.5s for
second change, for 1s for minute change, hour
change and day change. Resetting respective
enabling bit to 0 clears the interrupt output
immediately.
Oscillator Square Wave Output
The CLK32 is the shaped output of the oscillator, an
open-drain output that requires an external pull-up
resistor. The pull-up resistor is pulled-up to the same
rail that powers the circuit that wants the clock input,
is easy for logic level interfacing between the RTC
circuit and the system. The pull-up resistance is
selected against the edge slope rate wanted and the
parasitic capacitance of the connection, which is
typically in range of 7pF to 35pF for pins and normal
trace width of 5mil to 10mil and length of 400mil to
1000mil. Typically, a 300k resistance is the highest
volume acceptable to most systems and placing the
resistor close to the input pin provides slightly better
performance. Refer to Figure 14 for the circuit
diagram.
Figure 14:
The Output Circuit of the CLK32 Output.
System VCC
RDDW
(Placed close
to input side )
ACT5880
CLK32
System
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