7721 datasheet(534/577 Pages) RENESAS

534 / 577 page

APPENDIX

7721 Group User’s Manual

17–71

Appendix 9. 7721 Group Q & A

Interrupt

(1)

In both the edge sense and level sense, external interrupt requests occur when the input

____

signal to the INTi pin changes its level. This is independent of clock

φ1.

In the edge sense, the interrupt request bit is set to “1” at this time.

(2)

There are two methods: one uses external interrupt’s level sense, and the other uses the

timer’s event counter mode.

Method using external interrupt’s level sense

As for hardware, input a logical sum of multiple interrupt signals (e.g., ‘a’, ‘b’, and ‘c’) to the

____

INTi pin, and input each signal to each corresponding port.

___

As for software, check the ports’ input levels in the INTi interrupt routine in order to detect

which signal (‘a’, ‘b’, or ‘c’) was input.

(1)

____

Which timing of clock

φ1 is the external interrupts (input signals to the INTi pin) detected?

(2)

____

How can four or more external interrupt input pins (INTi) be used?

Method using timer’s event counter mode

As for hardware, input interrupt signals to the TAiIN pins or TBiIN pins.

As for software, set the timer’s operating mode to the event counter mode. Then, set a value

“000016” into the timer register and select the valid edge.

The timer’s interrupt request occurs when an interrupt signal (selected valid edge) is input.

M37721

Port

INTi

7721 Datasheet(PDF) 534 Page - Renesas Technology Corp