sketc.ino

/* How many shift register chips are daisy-chained.
 */
#define NUMBER_OF_SHIFT_CHIPS   2

/* Width of data (how many ext lines).
 */
#define DATA_WIDTH   NUMBER_OF_SHIFT_CHIPS * 8

/* Width of pulse to trigger the shift register to read and latch.
 */
#define PULSE_WIDTH_USEC   5

/* Optional delay between shift register reads.
 */
#define POLL_DELAY_MSEC   1

/* You will need to change the "int" to "long" If the
 * NUMBER_OF_SHIFT_CHIPS is higher than 2.
 */
#define BYTES_VAL_T unsigned long

int ploadPin        = 8;  // Connects to Parallel load pin the 165
int clockEnablePin  = 9;  // Connects to Clock Enable pin the 165
int dataPin         = 11; // Connects to the Q7 pin the 165
int clockPin        = 12; // Connects to the Clock pin the 165

BYTES_VAL_T pinValues;
BYTES_VAL_T oldPinValues;

/* This function is essentially a "shift-in" routine reading the
 * serial Data from the shift register chips and representing
 * the state of those pins in an unsigned integer (or long).
 */
BYTES_VAL_T read_shift_regs()
{
  long bitVal;
  BYTES_VAL_T bytesVal = 0;

  /* Trigger a parallel Load to latch the state of the data lines,
   */
  digitalWrite(clockEnablePin, HIGH);
  digitalWrite(ploadPin, LOW);
  delayMicroseconds(PULSE_WIDTH_USEC);
  digitalWrite(ploadPin, HIGH);
  digitalWrite(clockEnablePin, LOW);

  /* Loop to read each bit value from the serial out line
   * of the SN74HC165N.
   */
  for(int i = 0; i < DATA_WIDTH; i++)
  {
    bitVal = digitalRead(dataPin);

    /* Set the corresponding bit in bytesVal.
     */
    bytesVal |= (bitVal << ((DATA_WIDTH-1) - i));

    /* Pulse the Clock (rising edge shifts the next bit).
     */
    digitalWrite(clockPin, HIGH);
    delayMicroseconds(PULSE_WIDTH_USEC);
    digitalWrite(clockPin, LOW);
  }

  return(bytesVal);
}

/* Dump the list of zones along with their current status.
 */
void display_pin_values()
{
  Serial.print("Pin States:\r\n");

  for(int i = 0; i < DATA_WIDTH; i++)
  {
    Serial.print("  Pin-");
    Serial.print(i);
    Serial.print(": ");

    if((pinValues >> i) & 1)
      Serial.print("HIGH");
    else
      Serial.print("LOW");

    Serial.print("\r\n");
  }

  Serial.print("\r\n");
}

void display_pin_pressed()
{
  for(int i = 0; i < DATA_WIDTH; i++)
  {

    if((pinValues >> i) != (oldPinValues >> i)){
      Serial.print("  Pin-");
      Serial.print(i);
      Serial.print("\r\n New Value");
      Serial.print(pinValues >> i);
      Serial.print("\r\n Old Value");
      Serial.print(oldPinValues >> i);
      Serial.print("\r\n");
    }
  }
}

int rl11 = 23;
int rl12 = 22;
int rl13 = 25;
int rl14 = 24;
int rl15 = 27;
int rl16 = 26;
int rl17 = 29;
int rl18 = 28;
int rl21 = 31;
int rl22 = 30;
int rl23 = 33;
int rl24 = 32;
int rl25 = 35;
int rl26 = 34;
int rl27 = 37;
int rl28 = 36;


// the setup routine runs once when you press
// reset:
void setup() {                
  // initialize the digital pin as an output.
  pinMode(rl11, OUTPUT);     
  pinMode(rl12, OUTPUT);     
  pinMode(rl13, OUTPUT);     
  pinMode(rl14, OUTPUT);     
  pinMode(rl15, OUTPUT);     
  pinMode(rl16, OUTPUT);     
  pinMode(rl17, OUTPUT);     
  pinMode(rl18, OUTPUT);     
  pinMode(rl21, OUTPUT);     
  pinMode(rl22, OUTPUT);     
  pinMode(rl23, OUTPUT);     
  pinMode(rl24, OUTPUT);     
  pinMode(rl25, OUTPUT);     
  pinMode(rl26, OUTPUT);     
  pinMode(rl27, OUTPUT);     
  pinMode(rl28, OUTPUT);     

  digitalWrite(rl11, LOW);
  digitalWrite(rl12, LOW);
  digitalWrite(rl13, LOW);
  digitalWrite(rl14, LOW);
  digitalWrite(rl15, LOW);
  digitalWrite(rl16, LOW);
  digitalWrite(rl17, LOW);
  digitalWrite(rl18, LOW);
  digitalWrite(rl21, LOW);
  digitalWrite(rl22, LOW);
  digitalWrite(rl23, LOW);
  digitalWrite(rl24, LOW);
  digitalWrite(rl25, LOW);

  digitalWrite(rl26, LOW);
  digitalWrite(rl27, LOW);
  digitalWrite(rl28, LOW);

  Serial.begin(9600);

  /* Initialize our digital pins...
   */
  pinMode(ploadPin, OUTPUT);
  pinMode(clockEnablePin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, INPUT);

  digitalWrite(clockPin, LOW);
  digitalWrite(ploadPin, HIGH);

  /* Read in and display the pin states at startup.
   */
  pinValues = read_shift_regs();
  display_pin_values();
  oldPinValues = pinValues;

}

// the loop routine runs over and over again forever:
void loop() {         // wait for a second  // wait for a second
  /* Read the state of all zones.
   */
  pinValues = read_shift_regs();

  /* If there was a chage in state, display which ones changed.
   */
  if(pinValues != oldPinValues)
  {
    Serial.print("*Pin value change detected*\r\n");
    //        display_pin_values();
    display_pin_pressed();
    oldPinValues = pinValues;
  }

  delay(POLL_DELAY_MSEC);
}