This week we attach a shift register to an Arduino to demonstrate how to use a shift register to multiply the number of outputs that you can have on an Arduino.

This is our first week on using shift registers and we go over the basics of sending the serial data to the shift register from the Arduino.

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Basic Shift Register

/*############################## BASIC SHIFT REGISTER ##################################
       This sketch basically starts at 0 and counts up to 255 and outputs the number
       to the shift register.  In the code you can see how simple it is to communicate
       to a shift register.
     
       A shift register allows you to expand on the number of outputs that a device like
       an arduino can do.  
     
       To understand how the numbers correlate to the pins on the shift register you
       need to understand how a number can be translated into binary.  Here are some
       good links to better describe binary:
         http://en.wikipedia.org/wiki/Binary_number
         http://www.steveharrell.com/computer/binary.htm
         http://www.howstuffworks.com/binary-and-hexadecimal-number-systems.htm  

 
   From: Mike Myers (http://mikemyers.me)  @netnutmike
       Let's Make It Episode 17 (http://tech-zen.tv/index.php/shows/let-s-make-it/episodes/112-shift-registers-and-an-arduino-episode-17)
       
       http://tech-zen.tv
       
       For the sample code, show notes, contact information and many more 
       videos, visit the show page at http://tech-zen.tv/letsmakeit

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################################################################################*/

//Pin connected to RCK of TPIC6B595
int latchPin = 8;
//Pin connected to SRCK of TPIC6B595
int clockPin = 12;
////Pin connected to SER IN of TPIC6B595
int dataPin = 11;



void setup() {
  //set pins to output so you can control the shift register
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
}

void loop() {
  // count from 0 to 255 and display the number 
  // on the LEDs
  for (int numberToDisplay = 0; numberToDisplay < 256; numberToDisplay++) {
    // take the latchPin low so 
    // the LEDs don't change while you're sending in bits:
    digitalWrite(latchPin, LOW);
    // shift out the bits:
    shiftOut(dataPin, clockPin, MSBFIRST, numberToDisplay);  

    //take the latch pin high so the LEDs will light up:
    digitalWrite(latchPin, HIGH);
    
    // pause before next value:
    delay(500);
  }
}

More Complex Single Shift Register

This code was provided courtesy of Bob Powell.  The latest code is hosted at github and can be gotten from: https://github.com/texanfromiowa