M38203M4 Datasheet, PDF (164/344 Pages) Mitsubishi Electric Semiconductor – 8-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.3 Timer X and timer Y
Ringing pulse from
telephone line
16 Hz
OFF ON
Waveform-shaped signal
input to microcomputer
Approx. 1 second
Ringing duration
Approx. 2 second
No ringing duration
Fig. 2.3.38 Ringer signal waveform
<When a normal-range ringing pulse is input>
<When abnormal ringing pulse is input>
Signal input to
microcomputer
Ringing No ringing duration
duration
Approx.
1 second
Approx. 2 second
Signal input to
microcomputer
Ringing duration
Approx.
1.2 second or more
No ringing
duration
Timer X
value
Reload
Timer X
interrupt
4 to 23 interrupts occur
CNTR0
interrupt
Timer X
value
Reload
Timer X
interrupt
24 or more interrupts occur
CNTR0
interrupt
Fig. 2.3.39 Operation timing when ringing pulse is input
2–78
3820 GROUP USER’S MANUAL