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7470/7471/7477/7478 GROUP USER’S MANUAL

HARDWARE

1.11 Interrupts

1-49

(1) INT interrupt

When detecting a rising edge or a falling edge of each INT pin (INT0, INT1), the microcomputer

generates an INT interrupt request.These polarity is selected by the edge polarity selection register

(EG: Address 00D416).

2 P30, P31 pins

The INT0 and INT1 pins are used in common with the P30 and P31 pins and always detect the

levels of P30 and P31.

2 In the stop mode/wait mode

When bit 5 of the Edge polarity selection register is “0,” a restoration can be attained by the INT

interrupt from the stop mode/wait mode state provided by the STP/WIT instruction. For the details,

refer to “1.17 Low-power dissipation function.”

2 After reset

At reset release, the Edge polarity selection register is cleared to “0016,” so the INT0 and INT1

interrupts generate the interrupt request by detecting a falling edge. At reset release, however, the

Interrupt control register is put into the interrupt disable state, so any interrupt is not accepted.

Note: The INT0 and INT1 pins are used in common with input port P30 and P31, however, there is

no register for switching between the INT pins and the ports, so the active edges of P30 and

P31 are always detected. When these pins are used as ports, put the corresponding INT

interrupt into the disable state.

In the INT interrupt enable state, the INT interrupt is generated by a pin level change, thereby

causing a program run away.

(2) Key-on wake up interrupt

When bit 5 of the Edge polarity selection register is “1,” the key-on wake up interrupt request is

generated by applying the “L” level to any pin of P0 being an input port in the stop mode/wait mode

provided by the STP/WIT instruction, so that a recovery can be attained from the stop mode/wait

mode.

2 After reset

At reset release, bit 5 of the Edge polarity selection register is cleared to “0” so that the key-on

wake up interrupt request does not occur in the stop mode/wait mode.

Notes 1: In modes other than the stop mode/wait mode, the key-on wake up interrupt is disabled.

2: To select the stop mode/wait mode by the STP/WIT instruction when the interrupt disable

flag is cleared to “0” and bit 5 of the Edge polarity selection register is set to “1,” set every

input to P0 to “H.”

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