diff options
Diffstat (limited to 'source/lang')
| -rw-r--r-- | source/lang/api/constants.rst | 8 | ||||
| -rw-r--r-- | source/lang/api/shiftout.rst | 99 | ||||
| -rw-r--r-- | source/lang/unimplemented/shiftout.rst | 136 |
3 files changed, 99 insertions, 144 deletions
diff --git a/source/lang/api/constants.rst b/source/lang/api/constants.rst index 72738b8..2e968e7 100644 --- a/source/lang/api/constants.rst +++ b/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/source/lang/api/shiftout.rst b/source/lang/api/shiftout.rst new file mode 100644 index 0000000..1d9ba12 --- /dev/null +++ b/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 diff --git a/source/lang/unimplemented/shiftout.rst b/source/lang/unimplemented/shiftout.rst deleted file mode 100644 index ff3852f..0000000 --- a/source/lang/unimplemented/shiftout.rst +++ /dev/null @@ -1,136 +0,0 @@ -.. _lang-shiftout: - -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. - - - -This is a software implementation; Arduino (as of 0019) also -provides an `SPI library <http://arduino.cc/en/Reference/SPI>`_ -that uses the hardware implementation. - - - -Syntax ------- - -shiftOut(dataPin, clockPin, bitOrder, value) - - - -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**. -(Most Significant Bit First, or, Least Significant Bit First) - - - -value: the data to shift out. (*byte*) - - - -Returns -------- - -None - - - -Note ----- - -The **dataPin** and **clockPin** must already be configured as -outputs by a call to -`pinMode <http://arduino.cc/en/Reference/PinMode>`_\ (). - - - -**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 - 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)); - - - -Example -------- - -*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 |