4 channel multiplexer CocoTouch Midi Out
Channel Select:
- Attiny Pin 4 (GND) ->> 4051 S0 pin 11 (always LOW)
- Attiny Pin 5 -> 4051 S1 Pin 9
- Attiny Pin 6 -> 4051 S2 Pin 10
Capacitive sensing:
- Attiny Pin 3 sense (PB2) -> 4051 Z Pin 3
- Attiny Pin 7 reference (PB4) -> floating
by this table
http://arduinolearning.com/wp-content/uploads/2015/12/4051-truth-table.jpg
we can only get value from channel 0, 2, 4 ,6 (since S0 always L)
so we get value from pin 13, 15, 1, 2
reference: http://playground.arduino.cc/Learning/4051