Reading 16 digital inputs

This post relates to the previous one and is an extension of trying to help Phil Savard on the Littlebird Electronics forum.

Circuit
The schematic that can be used is to be found in example number two ("Daisy Chaining") in the Arduino ShiftIn tutorial. However, the pin numbers have been changed in the Arduino code to match whatever pins are used as data, clock and latch.


Breadboard
Note that there are no switches or devices currently connected to the 4021s. This is so that the wiring is easier to see.



Max/MSP Patch
The Max/MSP patch can be downloaded here.





Arduino Code
The Arduino code is almost a duplicate of what can be found on the Arduino ShiftIn tutorial. Note that the pin numbers have been changed in the Arduino code to match whatever pins are used as data, clock and latch.

int latchPin = 2;

int dataPin = 4;
int clockPin = 3;

byte switchVar1 = 0;
byte switchVar2 = 0;

void setup() {
Serial.begin(57600);

pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, INPUT);

}

void loop() {
digitalWrite(latchPin,1);

delayMicroseconds(20);
digitalWrite(latchPin,0);
switchVar1 = shiftIn(dataPin, clockPin);

switchVar2 = shiftIn(dataPin, clockPin);
Serial.print(switchVar1);

Serial.print(switchVar2);
delay(10);
}

byte shiftIn(int myDataPin, int myClockPin) {
int i;

int temp = 0;
int pinState;
byte myDataIn = 0;

pinMode(myClockPin, OUTPUT);
pinMode(myDataPin, INPUT);

for (i=7; i>=0; i--)

{
digitalWrite(myClockPin, 0);
delayMicroseconds(0.2);

temp = digitalRead(myDataPin);
if (temp) {

  pinState = 1;
  myDataIn = myDataIn | (1 << i);

}
else {
  pinState = 0;
}

digitalWrite(myClockPin, 1);
}
return myDataIn;

}