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Chapter 7 AC Zero-Cross Circuit/Noise Filter
124
7-3 Noise Filter
7-3-1 Overview
External interrupt pins IRQ0 and IRQ1 contain noise filtering circuit. This
circuitry can be used for remote control signal reception.
Figure 7-3-1 Noise Filtering Circuit Block Diagram
Noise Filter
Data bus
NFCTR
NF1EN
NF1CKS0
fs/2
8
fs/2
2
fs/2
9
fs/2
10
MUX
Noise filter
To IRQ0
interrupt
P20/IRQ0
MUX
NF0CKS1
NF0CKS0
NF0EN
NF1CKS1
2
2
MUX
Noise filter
To IRQ1
interrupt
P21/IRQ1/SENS
MUX
0
7
fs/2
8
fs/2
2
fs/2
9
fs/2
10
AC zero-cross
circuit
(Fig.7-1-1)
IRQ0: External interrupt 0
IRQ1: External interrupt 1