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2. APPLICATION

MITSUBISHI MICROCOMPUTER

3819 Group

2.7 Zero cross detection circuit

3819 Group USER’S MANUAL

2.7.3 Zero cross detection circuit application example 1

Clock count using ZCR interrupt (without using a noise filter)

Outline : The clock is counted up every second by using the ZCR interrupts.

Specifications : • The noise filter is not used.

• The commercial frequency (50 Hz or 60 Hz) is input.

• The clock is counted up by using the ZCR interrupts.

Figure 2. 7. 6 shows a setting of related registers.

Fig. 2.7.6 Setting of related registers [Clock count using ZCR interrupt (without using a noise filter)]

Passing through the zero cross detection circuit ( Note)

ZCRCON

Zero cross detection control register (Address:3916)

0 0

Noise filter sampling clock : without using a noise filter

ZCR active edge : Falling edge active ( Note)

INTEDGE

Interrupt edge selection register (Address:3A16)

IREQ1

Interrupt request register 1 (Address:3C16

)

Set the INT1/ZCR interrupt request bit to “0”

ICON1

Interrupt control register 1 (Address:3E16

)

INT1/ZCR interrupt : Enabled

IREQ1

Interrupt request register 1 (Address:3C16

)

ZCR interrupt request

When changing the values of bit 0 of the zero cross detection control register and bit 1 of the

interrupt edge selection register, make sure the following contents.

1. During changeing, set bit 1 of the interrupt control register 1 to “0”.

2. After changeing, set bit 1 of the interrupt request register 1 to “0”.

Note :

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