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Q
Which timing of clock φ
(1)
(2)
How can four or more external interrupt input pins (INT
A
(1) In both the edge sense and level sense, external interrupt requests occur when the input
____
signal to the INT
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.
Using external interrupt's level sense
In hardware, input a logical sum of multiple interrupt signals (e.g., 'a', 'b', and 'c') to the INT
pin, and input each signal to each corresponding port.
In software, check the port's input levels in the INT
of the signals 'a', 'b', and 'c' is input.
Using timer's event counter mode
In hardware, input interrupt signals to the TAi
In software, set the timer's operating mode to the event counter mode and a value "0000
into the timer register to the effective edge.
The timer's interrupt request occurs when an interrupt signal (selected effective edge) is input.
is the external interrupts (input signals to the INT
1
pin changes its level regardless of clock φ
i
7751 Group User's Manual
____
) be used?
i
.
1
___
interrupt routine to determine that which
i
M37751
Port
Port
Port
INT
i
pins or TBi
pins.
IN
IN
APPENDIX
Appendix 9. Q & A
Interrupt
____
pin) detected?
i
____
i
"
16
20–75
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