An abstract base class for Extended Input/Output elements. More...

#include <AH/Hardware/ExtendedInputOutput/ExtendedIOElement.hpp>

Inheritance diagram for ExtendedIOElement:

Collaboration diagram for ExtendedIOElement:

Public Member Functions
virtual	~ExtendedIOElement ()

virtual void	pinMode (pin_t pin, uint8_t mode)=0
	Set the mode of a given pin. More...

virtual void	digitalWrite (pin_t pin, uint8_t state)=0
	Set the output of the given pin to the given state. More...

virtual int	digitalRead (pin_t pin)=0
	Read the state of the given pin. More...

virtual void	analogWrite (pin_t pin, analog_t val)=0
	Write an analog (or PWM) value to the given pin. More...

virtual analog_t	analogRead (pin_t pin)=0
	Read the analog value of the given pin. More...

virtual void	begin ()=0
	Initialize the extended IO element. More...

virtual void	update ()=0
	Update the extended IO element: write the internal state to the physical outputs, or read the physical state into the input buffers. More...

pin_t	pin (pin_t pin) const
	Get the extended IO pin number of a given physical pin of this extended IO element. More...

pin_t	operator[] (pin_t pin) const
	Get the extended IO pin number of a given physical pin of this extended IO element. More...

pin_t	getLength () const
	Get the number of pins this IO element has. More...

pin_t	getEnd () const
	Get the largest global extended IO pin number that belongs to this extended IO element. More...

pin_t	getStart () const
	Get the smallest global extended IO pin number that belongs to this extended IO element. More...

Static Public Member Functions
static void	beginAll ()
	Initialize all extended IO elements. More...

static DoublyLinkedList< ExtendedIOElement > &	getAll ()
	Get the list of all Extended IO elements. More...

Protected Member Functions
	ExtendedIOElement (pin_t length)
	Create an ExtendedIOElement with the given number of pins. More...

Protected Attributes
ExtendedIOElement *	next

ExtendedIOElement *	previous

Private Attributes
const pin_t	length

const pin_t	start

const pin_t	end

Static Private Attributes
static pin_t	offset = NUM_DIGITAL_PINS + NUM_ANALOG_INPUTS

static DoublyLinkedList< ExtendedIOElement >	elements

Detailed Description

An abstract base class for Extended Input/Output elements.

The limited number of IO pins of the Arduino can be extended by adding multiplexers, shift registers, IO expanders, etc.
ExtendedIOElement serves as a base class for all these expanders.

The pins of each extended IO element are mapped to a pin number greater than the greatest Arduino pin number.
You can supply this pin number to the IO functions in the ExtIO namespace.
If the pin number corresponds to an actual Arduino pin, the default Arduino IO function (digitalRead, digitalWrite, ...) will be called.
If the pin is not an Arduino pin, it is an extended IO pin number, so the extended IO element that this pin belongs to is looked up, and the IO function for this element is executed with the correct pin number.

For example: Imagine an Arduino with 20 pins (e.g. the Arduino UNO). Pins 0 - 19 will correspond to the Arduino pins, and ExtIO::digitalRead(pin) will have the exact same effect as the standard digitalRead(pin) function (albeit a little slower).
Now, we'll add two 8-channel analog multiplexers, let's call them mux1 and mux2.
The first pin (pin 0) of mux1 will be extended IO pin number 20, the last pin (pin 7) of mux1 will be extended IO pin number 27, etc. The first pin of mux2 will be extended IO pin number 28, you get the idea. If you now call ExtIO::digitalRead(mux1.#pin (7)) or ExtIO::digitalRead(27), both will be translated to mux1.digitalRead(7).

The number of extended IO elements is limited only by the size of pin_t. However, looking up the extended IO element for a given extended IO pin number uses linear search, so that might add some noticable overhead for large pin numbers.

The design here is a compromise: saving a pointer to each extended IO element to find it directly would be much faster than having to search all elements each time. On the other hand, it would require each pin_t variable to be at least one byte larger. Since almost all other classes in this library store pin variables, the memory penalty would be too large, especially on AVR microcontrollers.
Another reason to do it this way, is that this approach is still fast enough to make sure it is not noticable to human users.

Definition at line 62 of file ExtendedIOElement.hpp.

Constructor & Destructor Documentation

◆ ExtendedIOElement()

ExtendedIOElement ( pin_t length )

protected

Create an ExtendedIOElement with the given number of pins.

Parameters

length The number of pins this element has.

Definition at line 10 of file ExtendedIOElement.cpp.

◆ ~ExtendedIOElement()

~ExtendedIOElement ( )

virtual

Definition at line 21 of file ExtendedIOElement.cpp.

Member Function Documentation

◆ pinMode()

virtual void pinMode	(	pin_t	pin,
		uint8_t	mode
	)

pure virtual

Set the mode of a given pin.

Note: This function might not be implemented by all subclasses.
Some extended IO types, such as shift registers, can only be used as outputs.
On others, it might be implemented, but it could impact all pins of the IO element. For example, enabling the internal pull-up resistor on an analog multiplexer affects all pins of the mux.

Parameters

pin	The (zero-based) pin of this IO element.
mode	The mode to set the pin to (e.g. `INPUT`, `OUTPUT` or `INPUT_PULLUP`).

Implemented in ShiftRegisterOutBase< N >, MAX7219, and AnalogMultiplex< N >.

◆ digitalWrite()

virtual void digitalWrite	(	pin_t	pin,
		uint8_t	state
	)

pure virtual

Set the output of the given pin to the given state.

Parameters

pin	The (zero-based) pin of this IO element.
state	The new state to set the pin to.

Implemented in AnalogMultiplex< N >, ShiftRegisterOutBase< N >, and MAX7219.

◆ digitalRead()

virtual int digitalRead ( pin_t pin )

pure virtual

Read the state of the given pin.

Parameters

pin	The (zero-based) pin of this IO element.

Returns: The state of the given pin.

Implemented in AnalogMultiplex< N >, ShiftRegisterOutBase< N >, and MAX7219.

◆ analogWrite()

virtual void analogWrite	(	pin_t	pin,
		analog_t	val
	)

pure virtual

Write an analog (or PWM) value to the given pin.

Parameters

pin	The (zero-based) pin of this IO element.
val	The new analog value to set the pin to.

Implemented in AnalogMultiplex< N >, ShiftRegisterOutBase< N >, and MAX7219.

◆ analogRead()

virtual analog_t analogRead ( pin_t pin )

pure virtual

Read the analog value of the given pin.

Parameters

pin	The (zero-based) pin of this IO element.

Returns: The new analog value of pin.

Implemented in ShiftRegisterOutBase< N >, MAX7219, and AnalogMultiplex< N >.

◆ begin()

virtual void begin ( )

pure virtual

Initialize the extended IO element.

Implemented in AnalogMultiplex< N >, ShiftRegisterOut< N >, SPIShiftRegisterOut< N >, and MAX7219.

◆ beginAll()

void beginAll ( )

static

Initialize all extended IO elements.

Definition at line 23 of file ExtendedIOElement.cpp.

◆ update()

virtual void update ( )

pure virtual

Update the extended IO element: write the internal state to the physical outputs, or read the physical state into the input buffers.

Implemented in MAX7219, AnalogMultiplex< N >, ShiftRegisterOut< N >, and SPIShiftRegisterOut< N >.

◆ pin()

pin_t pin ( pin_t pin ) const

Get the extended IO pin number of a given physical pin of this extended IO element.

Parameters

pin	The zero-based physical pin number of this IO element.

Returns: The global, unique extended IO pin number for the given pin.

Definition at line 28 of file ExtendedIOElement.cpp.

◆ operator[]()

pin_t operator[] ( pin_t pin ) const

Get the extended IO pin number of a given physical pin of this extended IO element.

It is alias for ExtendedIOElement::pin.

Parameters

pin	The zero-based physical pin number of this IO element.

Returns: The global, unique extended IO pin number for the given pin.

Definition at line 43 of file ExtendedIOElement.cpp.

◆ getLength()

pin_t getLength ( ) const

Get the number of pins this IO element has.

Returns: The number of pins this IO element has.

Definition at line 45 of file ExtendedIOElement.cpp.

◆ getEnd()

pin_t getEnd ( ) const

Get the largest global extended IO pin number that belongs to this extended IO element.

Definition at line 47 of file ExtendedIOElement.cpp.

◆ getStart()

pin_t getStart ( ) const

Get the smallest global extended IO pin number that belongs to this extended IO element.

Definition at line 49 of file ExtendedIOElement.cpp.

◆ getAll()

DoublyLinkedList< ExtendedIOElement > & getAll ( )

static

Get the list of all Extended IO elements.

Definition at line 51 of file ExtendedIOElement.cpp.

Member Data Documentation

◆ length

const pin_t length

private

Definition at line 192 of file ExtendedIOElement.hpp.

◆ start

const pin_t start

private

Definition at line 193 of file ExtendedIOElement.hpp.

◆ end

const pin_t end

private

Definition at line 194 of file ExtendedIOElement.hpp.

◆ offset

pin_t offset = NUM_DIGITAL_PINS + NUM_ANALOG_INPUTS

staticprivate

Definition at line 195 of file ExtendedIOElement.hpp.

◆ elements

DoublyLinkedList< ExtendedIOElement > elements

staticprivate

Definition at line 197 of file ExtendedIOElement.hpp.

◆ next

ExtendedIOElement * next

protectedinherited

Definition at line 305 of file LinkedList.hpp.

◆ previous

ExtendedIOElement * previous

protectedinherited

Definition at line 306 of file LinkedList.hpp.

The documentation for this class was generated from the following files:

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Private Attributes

Static Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ExtendedIOElement()

◆ ~ExtendedIOElement()

Member Function Documentation

◆ pinMode()

◆ digitalWrite()

◆ digitalRead()

◆ analogWrite()

◆ analogRead()

◆ begin()

◆ beginAll()

◆ update()

◆ pin()

◆ operator[]()

◆ getLength()

◆ getEnd()

◆ getStart()

◆ getAll()

Member Data Documentation

◆ length

◆ start

◆ end

◆ offset

◆ elements

◆ next

◆ previous