Serial not reading Input

Projects General Guidance
1

So i am trying to read the serial output from a 74HC165N chip. The chip should take 8 binary parallel inputs and convert them to a single serial output.

It does not even seem to read my switches at all. I tried with a different 74HC165N chip and i got the same result, so i don't think my chips are faulty.

Any idea what's going on? have i done something incorrectly in my code? This is how i wired up the 74HC165N chip.

1 (Shift/Load) -> Arduino #13
2 (Clock) -> Arduino #12
3-6, 11-14 (Inputs) -> DIP Switches
8 (GND) - Ground
9 (DATA) -> Arduino 11
15 (Clock INHB) -> Ground
16 (Vcc) -> Power +5v

With the switches wired like this

VCC -> DIP - > 10k resistor-> 74165 A pin

//The terminology used here (PL, CP, Q7 and so on) are taken DIRECTLY from the 74HC165's datasheet.

#define PIN_PL (13) //pin 13 on arduino goes to pin 1 of 74HC165
#define PIN_CP (12) //pin 12 on arduino goes to pin 2 of 74HC165
#define PIN_Q7 (11) //pin 11 on arduino goes to pin 9 of 74HC165
//Hardwire pin 15 of both 74HC165 chips to ground to enable them all the time.

//For peace of mind I also hardwired pin 10 of the upstream chip to
//GND to force zeroes to be shifted in instead of allowing it to float.
//Given that the arduino is "downstream".

void setup() 
{
  Serial.begin(9600);

  pinMode(PIN_PL, OUTPUT);
  pinMode(PIN_CP, OUTPUT);
  pinMode(PIN_Q7, INPUT);

  digitalWrite(PIN_PL, HIGH);
  digitalWrite(PIN_CP, LOW);

  int i;
  int j;
  int value;
  
  //read the switches 8 times to prove
  //that the system is stable
  for(i = 0 ; i < 7 ; i++)
  {
    //load logic bits from the DIP switches
    digitalWrite(PIN_PL, LOW);  //LOAD BITS
    //reset "load" line, this freezes the internal buffer on both chips
    digitalWrite(PIN_PL, HIGH);
              
    for(j = 0 ; j < 8 ; j++)
    {
      value = digitalRead(PIN_Q7);
  
      digitalWrite(PIN_CP, HIGH);
      digitalWrite(PIN_CP, LOW);
      
      //print switch's value
      Serial.print(value);
      
    }

    Serial.println("");    
    Serial.println("----------------");
    delay(1000);
  }   
}

void loop()
{
}
2

What does it print?

3

It simply prints "00000000", as if all the switches were off even if they are on.

I tried with a different code from the arduino playground as below(changing the pins as required).

http://www.arduino.cc/playground/Code/ShiftRegSN74HC165N

With the only change i made being

#define NUMBER_OF_SHIFT_CHIPS   1
int ploadPin        = 13;  // Connects to Parallel load pin the 165
int clockEnablePin  = 10;  // 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

And with that it prints as below, regardless the state of my switches.

Pin States:
  Pin-0: LOW
  Pin-1: LOW
  Pin-2: LOW
  Pin-3: LOW
  Pin-4: LOW
  Pin-5: LOW
  Pin-6: LOW
  Pin-7: LOW

I have a feeling its something to do with the way i have the switches wired. This is how i have them now.

VCC -> Switch - > 10K Resistor(connected to ground) - > 74165 A pin
VCC -> Switch - > 10K Resistor(connected to ground) - > 74165 B pin
etc..

4

Could you sketch that? The way you describe it, it sounds like the pin is connected to ground.

5

I've attached the schematic of it, I'm essentially trying to do what this guy did, but with one register.

http://wardyprojects.blogspot.com.au/2011/05/74hc165-piso-shift-register-arduino.html

Schematic.png

6

ThievingSix:
I tried with a different code from the arduino playground as below(changing the pins as required).

http://www.arduino.cc/playground/Code/ShiftRegSN74HC165N

With the only change i made being ...

That's not the only change you made. He had:

  /* 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);

You have:

    //load logic bits from the DIP switches
    digitalWrite(PIN_PL, LOW);  //LOAD BITS
    //reset "load" line, this freezes the internal buffer on both chips
    digitalWrite(PIN_PL, HIGH);