MultiShiftRegister

MultiShiftRegister (MSR) is an Arduino library for easily interfacing with multiple daisy-chained SIPO (Serial In, Parallel Out) latching shift registers (such as the 74HC595) to greatly expand the number of binary outputs available to the developer.

Requirements

MSR expects the shift registers to use a CLOCK pin, a LATCH pin, and a DATA pin to control input.

Installation

Copy all the files in this repository into a MultiShiftRegister folder in your libraries folder found in the root of your sketchbook folder.

Use

#include <MultiShiftRegister.h>

int latchPin  = 8;
int clockPin = 12;
int dataPin = 11;

# How many 8 bit shift registers we're talking to.
# Two 8 bit registers can host 16 individuallly
# addressable binary outputs.
int numberOfRegisters = 2;

# Setup group of shift registers and name it `msr`.
# All outputs are initialized to low/off.
MultiShiftRegister msr (numberOfRegisters , latchPin, clockPin, dataPin); 

void setup() {
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
}

void loop() {
  # Prepare to turn on pin 5.
  # Pin 5 is still low/off.
  msr.set(5);

  # Shift data out, with appropriate latches.
  # Pin 5 is now high/on.
  msr.shift();

  delay(1000);

  # Turn pin 5 back off.
  msr.clear(5);
  msr.shift();

  delay(1000);

  # Turn pin 12 (4th output on the second shift register).
  # on and off again.
  msr.set(12); 
  msr.shift(); 
  delay(1000);
  msr.clear(12); 
  msr.shift(); 

  delay(1000);

  # This set and shift business is getting repetitive.
  # Let's do it in one line instead.
  msr.set_shift(14);
  delay(1000);
  msr.clear_shift(14);

  delay(1000);

  # But wait, this is inefficient. It doesn't actually turn
  # outputs 5 and 12 on simultaneously. There a very tiny delay
  # as it shifts output 5 before setting output 12. This may or
  # may not be a problem, depending on your application.
  msr.set_shift(5);
  msr.set_shift(12);
  delay(1000);
  msr.clear_shift(5);
  msr.clear_shift(12);

  delay(1000);

  # So, consider doing this to prepare both outputs before shifting them.
  msr.set(5);
  msr.set(12);
  msr.shift();
  delay(1000);
  msr.clear(5);
  msr.clear(12);
  msr.shift();

  delay(1000);
}