Arduino + Reading PCF8574 Pins as Inputs

#include <Wire.h>
#define expander B0111000 //pcf8574 with all address pins grounded
/* see <a href="http://www.practicalmaker.com/tutorials/port-expander-shield-documentation
for">http://www.practicalmaker.com/tutorials/port-expander-shield-documentati...</a> more info on configuring a pcf8574.
 
That article will also give you sample code as to how to toggle pcf8574 pins on
and off.
 
on the port expander shield the top row of pins is the one which you use to test statuses
 
*/
 
void setup() {
  Wire.begin();
  Serial.begin(9600);
  expanderWrite(B11111111);
  pinMode(13, OUTPUT);
}
 
void loop() {
  byte pin_number = 0; //check status of pin 0
 
  /* querying the pcf8574 returns a byte. each bit is the current status of each of
  the 8 pins. 0 = low, 1 = high */
  byte returnByte = expanderRead();
 
  // we can use a funciton called bitread to get the status of any bit in the byte
  // pin number starts at 0
  boolean bitStatus = bitRead(returnByte, pin_number);
 
  if(bitStatus == 1) {
    digitalWrite(13, HIGH);
  } else {
    digitalWrite(13, LOW);
  }
 
  Serial.println(bitStatus, BIN);
 
  delay(500);
}
 
void expanderWrite(byte _data ) {
  Wire.beginTransmission(expander);
  Wire.send(_data);
  Wire.endTransmission();
}
 
byte expanderRead() {
  byte _data;
  Wire.requestFrom(expander, 1);
  if(Wire.available()) {
    _data = Wire.receive();
  }
  return _data;
}