From 9579e9487c2039df38cc4fd0ac2846ef07cc0947 Mon Sep 17 00:00:00 2001
From: Marti Bolivar <mbolivar@leaflabs.com>
Date: Fri, 11 Mar 2011 20:43:59 -0500
Subject: shiftOut(), docs fixes
---
docs/source/lang/api/constants.rst | 8 ---
docs/source/lang/api/shiftout.rst | 99 ++++++++++++++++++++++++++++++++++++++
2 files changed, 99 insertions(+), 8 deletions(-)
create mode 100644 docs/source/lang/api/shiftout.rst
(limited to 'docs/source/lang/api')
diff --git a/docs/source/lang/api/constants.rst b/docs/source/lang/api/constants.rst
index 72738b8..2e968e7 100644
--- a/docs/source/lang/api/constants.rst
+++ b/docs/source/lang/api/constants.rst
@@ -61,14 +61,6 @@ pin is configured as an ``INPUT`` (using :ref:`pinMode()
<lang-digitalread>`, the microcontroller will report ``HIGH`` if a
voltage of 3 volts or more is present at the pin.
-.. TODO? Following seems false; check it out sometime, leave out for now:
-
-.. A pin may also be configured as an ``INPUT`` with ``pinMode()``, and
-.. subsequently made ``HIGH`` with :ref:`digitalWrite()
-.. <lang-digitalwrite>`, this will set the internal pullup resistors,
-.. which will *steer* the input pin to a HIGH reading unless it is pulled
-.. LOW by external circuitry.
-
When a pin is configured to ``OUTPUT`` with pinMode, and set to
``HIGH`` with :ref:`digitalWrite() <lang-digitalwrite>`, the pin is at
3.3 volts. In this state it can *source* current, e.g. light an LED
diff --git a/docs/source/lang/api/shiftout.rst b/docs/source/lang/api/shiftout.rst
new file mode 100644
index 0000000..1d9ba12
--- /dev/null
+++ b/docs/source/lang/api/shiftout.rst
@@ -0,0 +1,99 @@
+.. 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
--
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