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).

(:source lang=arduino tabwidth=4:)

shiftOut(dataPin, clock, LSBFIRST, (data >> 8));

(:sourceend:)

(:source lang=arduino tabwidth=4:) //**************************************************************//

}

(:sourceend:)

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

See also

• shiftIn()
• SPI

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 to indicate that the bit is available.

This is a software implementation; Arduino (as of 0019) also provides an SPI library that uses the hardware implementation.

int data = 500;

shiftOut is currently written to output 1 byte (8 bits) so it requires a two step operation to output values larger than 255.

[@

shiftOut(dataPin, clock, LSBFIRST, (data >> 8)); @]

shiftOut is currently written to output 1 byte (8 bits) so it requires a two step operation to output values larger than 255.

// Do this for MSBFIRST serial 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));

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 toggled to indicate that the bit is available.

This is known as synchronous serial protocol and is a common way that microcontrollers communicate with sensors, and with other microcontrollers. The two devices stay synchronized, and communicate at close to maximum speeds, since they both share the same clock line. This is often referred to in chip hardware documentation as Serial Peripheral Interface (SPI).

Syntax

shiftOut(dataPin, clockPin, bitOrder, value)

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

See

This is known as synchronous serial protocol and is a common way that microcontrollers communicate with sensors, and with other microcontrollers. The two devices always stay synchronized, and communicate at close to maximum speeds, since they both share the same clock line. This is often referred to in chip hardware documentation as Serial Peripheral Interface (SPI)

This is known as synchronous serial protocol and is a common way that microcontrollers communicate with sensors, and with other microcontrollers. The two devices always stay synchronized, and communicate at close to maximum speeds, since they both share the same clock line. This is often referred to in chip hardware documentation as Synchronous Peripheral Interface (SPI)

This is known as synchronous serial protocol and is a common way that microcontrollers communicate with sensors, and with other microcontrollers. The two devices always stay synchronized, and communicate at close to maximum speeds, since they both share the same clock line. This is often referred to in hardware documentation as Synchronous Peripheral Interface (SPI)

This is known as synchronous serial protocol and is a common way that microcontrollers communicate with sensors, and with other microcontrollers. The two devices always stay synchronized, and communicate at close to maximum speeds, since they both share the same clock line.

Note

Note that this function, as it is currently written, is hard-wired to output 8 bits at a time. An int holds two bytes (16 bits), so outputting an int with shiftout requires a two-step operation:

Example:

int data;
int clock;
int cs;
...

digitalWrite(cs, LOW);
data = 500;
shiftOut(data, clock, MSBFIRST, data)
digitalWrite(cs, HIGH);

// this will actually only output 244 because 
// 500 % 256 = 244
// since only the low 8 bits are output

// Instead do this for MSBFIRST serial
data = 500;
// shift out highbyte
// " >> " is bitshift operator - moves top 8 bits (high byte) into low byte 
shiftOut(data, clock, MSBFIRST, (data >> 8));  

// shift out lowbyte
shiftOut(data, clock, MSBFIRST, data);



// And do this for LSBFIRST serial
data = 500;
// shift out lowbyte
shiftOut(data, clock, LSBFIRST, data);  

// shift out highbyte 
shiftOut(data, clock, LSBFIRST, (data >> 8));

shiftOut(data, clock, LSBFIRST, data);

shiftOut(data, clock, LSBFIRST, (data >> 8));

// " >> " is bitshift operator - moves top 8 bits (high byte) into low byte

Note also that this function, as it is currently written, is hard-wired to output 8 bits at a time. An int holds two bytes (16 bits), so outputting an int with shiftout requires a two-step operation:

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

bitOrder: which order to shift out the bits; either MSBFIRST or LSBFIRST.

bitOrder: which order to shift out the bits; either MSBFIRST or LSBFIRST.\\

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

Note also that this function, as it is currently written, is hard-wired to output 8 bits at a time. An int holds two bytes (16 bits), so if one tries to outputing an int with shiftout requires a two-step operation:

Example:

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 the dataPin, after which the clockPin is toggled to indicate that the bit is available.

// shift out lowbyte

// shift out highbyte

@]

// " >> " is bitshift operator - moves top 8 bit (high byte) into low byte shiftOut(data, clock, MSBFIRST, (data >> 8));

shiftOut(data, clock, MSBFIRST, (data >> 8)); // >> is bitshift operator - moves highbyte into lowbyte // shift out lowbyte

// And do this for LSBFIRST serial data = 500; shiftOut(data, clock, MSBFIRST, data);

This is known as synchronous serial protocol and is a common way that microcontrollers communicate with sensors, and with other microcontrollers. The two devices always stay synchronized, and communicate at close to maximum speeds, since they both share the same clock line. Often referred to as SPI (synchronous protocol interface) in hardware documentation.

Common Programming Errors

Common Errors

Note also that this function, as it is currently written, is hard-wired to output 8 bits at a time. An int holds two bytes (16 bits), so if one tries to do something like this:

Note also that this function, as it is currently written, only outputs 8 bits at a time. An int holds two bytes (16 bits), so if one tries to do something like this:

Note also that this function, as it is currently written, only outputs 8 bits at a time. An int holds two bytes, so if one tries to do something like this:

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 pin, after which another pin is toggled to indicate that the bit is available.

This is known as synchronous serial protocol and is a common way that microcontrollers communicate with sensors, and with other microcontrollers. The two devices always stay synchronized, and communicate at close to maximum speeds, since they both share the same clock line. Often referred to in hardware documentation as SPI.

Warning

Note also that this function, as it is currently written, only outputs 8 bits at a time. An int holds two bytes so if one tries to do something like this:

int data;
int clock;
int cs;
...

digitalWrite(cs, LOW);
data = 500;
shiftOut(data, clock, MSBFIRST, data)
digitalWrite(cs, HIGH);

// this will actually only output 244 because 
// 500 % 256 = 244
// since only the low 8 bits are output

// Instead do this for MSBFIRST serial
data = 500;
shiftOut(data, clock, MSBFIRST, (data >> 8));  
// shift out highbyte
shiftOut(data, clock, MSBFIRST, data);
// shift out lowbyte


// And do this for LSBFIRST serial
data = 500;
shiftOut(data, clock, MSBFIRST, data);  
// shift out lowbyte
shiftOut(data, clock, MSBFIRST, (data >> 8));
// shift out highbyte 

[@//**************************************************************//

 [@//**************************************************************//

 [@ //**************************************************************//

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

} @]

Note

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

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

// Name : shiftOutCode, Hello World // // Author : Carlyn Maw,Tom Igoe //

shiftOut(dataPin, clockPin, bitOrder, value)

Description

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 pin, after which another pin is toggled to indicate that the bit is available.

Parameters

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).

value: the data to shift out. (byte)

Returns

None

Example

 
//**************************************************************//
//  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);
  }
}

Note

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

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