NEC PD75P402 Uživatelský manuál Strana 141

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CHAPTER 6. INTERRUPT FUNCTIONS
(2) External interrupt input pin hardware
The configuration of INT0 and INT2 is shown in Fig. 6-3.
Fig. 6-3 Configuration of INT0 and INT2
4
IM0
Input
Buffer
Input Buffer 
with Hysteresis 
Characteristics
Internal Bus
INT2/P12
INT0/P10
Sampling Clock
Noise Elimina-
tion Circuit
Selector
Analog Delay
Noise Elimina-
tion Circuit
Φ
f
xx
64
Edge Detec-
tion Circuit
Rising Edge
Detection
Circuit
Φ
IM01, IM00
IM03
2
INT0
(IRQ0 Setting Signal)
INT2
(IRQ2 Setting Signal)
INT0 functions as an external interrupt input on which sampling clock noise elimination and detected edge
selection can be performed. The INT0 noise elimination circuit detects a change in level in 2 sampling clock pulses.
Therefore, pulses narrower than the width of the 2 cycles (2t
CY* or 128/fXX) of sampling clock are eliminated as noise,
and a pulse exceeding the width is properly acknowledged as an interrupt signal (see Fig. 6-4). One of 3 clocks can
be selected as the timing clocks.
* Cycle time
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