shiftOut

Forum 2005-2010 (read only) Software Syntax & Programs
1

I ordered some shift registers to play around with but I can't make heads or tails of any other the tutorials. Does anyone know of a tutorial that actually makes sense? Like say I want to turn on pin 1 and 4 how can I do that? Everything I see is set up to just turn something on and off in order in, like the nightrider thing and that seems useless..

2

The documentation for shiftOut says:

shiftOut()
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 data pin, after which a clock pin is pulsed to indicate that the bit is available.

The tutorials define how to write a bit, and toggle the clock pin.

As for the data to output, you might want to have a look at bitSet, bitRead(), bitWrite(), and bitClear(). These functions allow you to manipulate individual bits in a byte, which is what you seem to want to do.

Once you have the byte to output, shift it out just like the tutorials show.

3

Would anybody be willing to write some example code for switching pin 1 on and off?

4

Pin 1 is one of the pair of pins used for serial I/O. It is better not to use that pin, unless you absolutely have to. It will interfere with uploading sketches.

const int pinNum = 1;

digitalWrite(pinNum, HIGH); // Turn pin on
digitalWrite(pinNum, LOW);  // Turn pin off
5

Thanks for your quick replies. Sorry I should have been more clear in my question. Pin 1 of the shift register. Thanks again!

6

I presume that you have seen this: http://arduino.cc/en/Reference/ShiftOut

I presume, also that you have your shift register connected as shown here: http://arduino.cc/en/Tutorial/ShiftOut

Further, I presume that you mean you want to set only output pin 1 high.

byte outVal = 0; // Define output data
bitSet(outVal, 1); // Set bit 1
shiftOut(dataPin, clockPin, MSBFIRST, outVal);

(You may need to change MSBFIRST to LSBFIRST, if the right pin does not light up).

7

Alright.... What about pin 2 of the shift register? These things are so complicated to me for some reason...

8 
bitSet(outVal, 2); // Set bit 2

Please don't ask how to set bit 3 :slight_smile:

Rob