shiftOut()

Shifts out a byte of data one bit at a time. Starts from either the most (i.e. the leftmost) or least (rightmost) significant bit. Each bit is written in turn to a data pin, after which a clock pin is pulsed (taken high, then low) to indicate that the bit is available.

Note: if you're interfacing with a device that's clocked by rising edges, you'll need to make sure that the clock pin is low before the call to shiftOut(), e.g. with a call to digitalWrite(clockPin, LOW).

This is a software implementation; see also the SPI library, which provides a hardware implementation that is faster but works only on specific pins.

shiftOut(dataPin, clockPin, bitOrder, value)

dataPin: the pin on which to output each bit (int)

clockPin: the pin to toggle once the dataPin has been set to the correct value (int)

bitOrder: which order to shift out the bits; either MSBFIRST or LSBFIRST.
(Most Significant Bit First, or, Least Significant Bit First)

value: the data to shift out. (byte)

None

The dataPin and clockPin must already be configured as outputs by a call to pinMode().

shiftOut is currently written to output 1 byte (8 bits) so it requires a two step operation to output values larger than 255. (:source lang=arduino tabwidth=4:)

Do this for MSBFIRST serial int data = 500; shift out highbyte shiftOut(dataPin, clock, MSBFIRST, (data » 8)); shift out lowbyte shiftOut(data, clock, MSBFIRST, data); Or do this for LSBFIRST serial data = 500; shift out lowbyte shiftOut(dataPin, clock, LSBFIRST, data); shift out highbyte shiftOut(dataPin, clock, LSBFIRST, (data » 8));

(:sourceend:)

For accompanying circuit, see the tutorial on controlling a 74HC595 shift register.

(:source lang=arduino tabwidth=4:) Name : shiftOutCode, Hello World Author : Carlyn Maw,Tom Igoe Date : 25 Oct, 2006 Version : 1.0 Notes : Code for using a 74HC595 Shift Register : to count from 0 to 255 ** Pin connected to ST_CP of 74HC595 int latchPin = 8; Pin connected to SH_CP of 74HC595 int clockPin = 12; Pin connected to DS of 74HC595 int dataPin = 11; void setup() { set pins to output because they are addressed in the main loop

pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);

}

void loop() {

//count up routine
for (int j = 0; j < 256; j++) {
  //ground latchPin and hold low for as long as you are transmitting
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, LSBFIRST, j);   
  //return the latch pin high to signal chip that it 
  //no longer needs to listen for information
  digitalWrite(latchPin, HIGH);
  delay(1000);
}

}

(:sourceend:)

* shiftIn() * SPI Source: arduino.cc