Panasonic MN101C77C User Manual

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Chapter 3    Interrupts

External Interrupts

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AC Zero-Cross Detector Setup Example (External interrupt 1)

AC zero-cross detector generates the external interrupt 1 (IRQ1) by using P21/ACZ pin.

An example setup procedure, with a description of each step is shown below.

(1)

Set the P21IM flag of the noise filter control

register (NFCTR0) to "1" to select the AC

zero-cross detector signal as the external

interrupt 1 generation factor.

(2)

Set the interrupt level by the IRQ1LV 1-0

flag of the IRQ1ICR register.

If the interrupt request flag has been already

set, clear the interrupt flag.

           

[           Chapter 3  3-1-4. Interrupt flag setup ]

(3)

Set the IRQ1IE flag of the IRQ1ICR register to

"1" to enable the interrupt.

Setup Procedure

(1)

Select the AC zero-cross detector

signal.

NFCTR0 (x'3F8E')

bp7

: P21IM

= 1

(2)

Set the interrupt level.

IRQ1ICR (x'3FE3')

bp7-6

: IRQ1LV1-0 = 10

(3)

Enable the interrupt.

IRQ1ICR (x'3FE3')

bp1

: IRQ1IE

= 1

Description

When the input signal level from P21/ACZ pin crosses 1/2 V

DD

, the external interrupt 1 is generated.