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authorMarti Bolivar <mbolivar@leaflabs.com>2011-03-11 20:43:59 -0500
committerMarti Bolivar <mbolivar@leaflabs.com>2011-03-11 20:43:59 -0500
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shiftOut(), docs fixes
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+.. highlight:: cpp
+
+.. _lang-shiftout:
+
+shiftOut()
+==========
+
+Shift out a byte of data, one bit at a time.
+
+.. contents:: Contents
+ :local:
+
+Library Documentation
+---------------------
+
+.. doxygenfunction:: shiftOut
+
+Discussion
+----------
+
+This is a software implementation. There is also a hardware :ref:`SPI
+<spi>` library available which will be faster and consume less CPU
+cycles than this function.
+
+Note that the ``dataPin`` and ``clockPin`` must already be configured
+to :ref:`OUTPUT <lang-constants-output>` mode by a call to
+:ref:`pinMode() <lang-pinmode>`.
+
+Also note that since shiftOut() outputs 1 byte (8 bits) at a time, it
+requires multiple steps to output values larger than 255.
+
+Examples
+--------
+
+To use these examples, replace ``dataPin`` and ``clockPin`` with the
+numbers of the pins you want to use::
+
+ /* MSBFIRST example */
+
+ uint16 data = 500;
+ // shift out high byte
+ shiftOut(dataPin, clockPin, MSBFIRST, (data >> 8));
+ // shift out low byte
+ shiftOut(dataPin, clockPin, MSBFIRST, data);
+
+ /* LSBFIRST serial */
+
+ data = 500;
+ // shift out low byte
+ shiftOut(dataPin, clockPin, LSBFIRST, data);
+ // shift out high byte
+ shiftOut(dataPin, clockPin, LSBFIRST, (data >> 8));
+
+Arduino Tutorial Example
+------------------------
+
+This Arduino example runs unmodified on the Maple. For accompanying
+circuit, see the `tutorial on controlling a 74HC595 shift register
+<http://arduino.cc/en/Tutorial/ShiftOut>`_.
+
+::
+
+ //**************************************************************//
+ // 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);
+ }
+ }
+
+.. include:: /lang/cc-attribution.txt