PB0=L
PB1=L
WAIT
PB0=L
PB1=L
TALK
PB0=25Hz
PB1=H
RING
Line>37V
0.4s
20 ticks
1.6s
80 ticks
Line<20V
PB0=L
PB1=L
IDLE
Line>37V
Line<33V