4570 Datasheet, PDF (18/69 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
4570 Group
SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER
EXTERNAL INTERRUPTS
An external interrupt request occurs when a valid waveform (=
waveform causing the external 0 interrupt) is input to an interrupt
input pin (edge detection).
The external 0 interrupt can be controlled with the interrupt control
register I1.
Table 7 External interrupt activated condition
Name
Input pin
Valid waveform
External 0 interrupt P21/INT
Falling waveform (“H”→“L”)
Rising waveform (“L”→“H”)
Valid waveform
selection bit (I12)
0
1
P21/INT
I12
Falling
0
One-sided edge
detection circuit
1
Rising _SNZI0
instruction
EXF0
Skip
External 0
interrupt
Fig. 17 External interrupt circuit structure
17