AdafruitPCF8574ExpanderAdapter Class Reference

Description

An implementation of the GpioExpanderAdapter For Adafruit's PCF8574 library.

Details: https://learn.adafruit.com/adafruit-pcf8574

#include <AdafruitPCF8574ExpanderAdapter.h>

Inheritance diagram for AdafruitPCF8574ExpanderAdapter:

Public Member Functions
	AdafruitPCF8574ExpanderAdapter ()
	Construct a AdafruitPCF8574ExpanderAdapter. An Adafruit_PCF8574 instance will be created for you. More...
	AdafruitPCF8574ExpanderAdapter (Adafruit_PCF8574 &_pcf)
	Construct a AdafruitPCF8574ExpanderAdapter with an already created Adafruit_PCF8574 instance. More...
void	begin () override
	The default begin for a GPIOExpanderAdapter will use the default I2C address for the PCF8574. More...
bool	begin (uint8_t i2c_addr, TwoWire *wire=&Wire)
	Use this method instead of the default begin() to specify a different I2C addreess and optional Wire. More...
void	update () override
	Update the state of all input pins (called from loop() before updating EventButtons) More...
void	attachPin (byte pin, int mode=INPUT_PULLUP) override
	Attach a pin and set its pin mode. More...
bool	read (byte pin) override
	Returns the state of a pin on the expander. More...
bool	updateAndRead (byte pin)
	Update the expander over I2C and return a pin state. Not recommended, use a single uptate() and then multiple pin read()s in loop(). More...
void	write (byte pin, bool state)
	Write bool state to a pin. More...
bool	canWrite ()
	The PCF8574 can write a pins state. More...
Public Member Functions inherited from GpioExpanderAdapter
virtual void	begin ()=0
	Initialize the expander. (Idempotent) More...
virtual void	update ()=0
	Read the state of all pins on the expander. More...
virtual bool	read (byte pin)=0
	Returns the state of a pin on the expander. More...
virtual void	attachPin (byte pin, int mode=INPUT_PULLUP)=0
	Use it to configure individual pin mode, if expander allows it. Not all of them do. More...
void	write (byte pin, bool state)
	Optionally implemented by concrete GpioExpanderAdapters if they support writing to pins. More...
bool	canWrite ()
	Returns true if the concrete GpioExpanderAdapter has implemented the write() method. More...

Constructor & Destructor Documentation

AdafruitPCF8574ExpanderAdapter() [1/2]

AdafruitPCF8574ExpanderAdapter::AdafruitPCF8574ExpanderAdapter ( )

inline

Construct a AdafruitPCF8574ExpanderAdapter. An Adafruit_PCF8574 instance will be created for you.

This will create and Adafruit_PCF8574 on the stack - creating one on the heap causes a crash as the Adafruit lib tries to delete an object that doesn't yet exist for ESP32 in the begin().

AdafruitPCF8574ExpanderAdapter() [2/2]

AdafruitPCF8574ExpanderAdapter::AdafruitPCF8574ExpanderAdapter ( Adafruit_PCF8574 &  _pcf )

inline

Construct a AdafruitPCF8574ExpanderAdapter with an already created Adafruit_PCF8574 instance.

Parameters

_pcf

Member Function Documentation

attachPin()

void AdafruitPCF8574ExpanderAdapter::attachPin ( byte  pin, int  mode = INPUT_PULLUP  )

inlineoverridevirtual

Attach a pin and set its pin mode.

Parameters

pin	The pin number on the expander
mode	Default INPUT_PULLUP

Implements GpioExpanderAdapter.

begin() [1/2]

void AdafruitPCF8574ExpanderAdapter::begin ( void  )

inlineoverridevirtual

The default begin for a GPIOExpanderAdapter will use the default I2C address for the PCF8574.

Implements GpioExpanderAdapter.

begin() [2/2]

bool AdafruitPCF8574ExpanderAdapter::begin ( uint8_t  i2c_addr, TwoWire *  wire = &Wire  )

inline

Use this method instead of the default begin() to specify a different I2C addreess and optional Wire.

Parameters

i2c_addr	The I2C address to use for the PCF8574
wire	Optional

Returns

true

false

canWrite()

bool AdafruitPCF8574ExpanderAdapter::canWrite ( )

inline

The PCF8574 can write a pins state.

Returns

true

read()

bool AdafruitPCF8574ExpanderAdapter::read ( byte  pin )

inlineoverridevirtual

Returns the state of a pin on the expander.

Parameters

pin	The pin number on the expander board

Returns

true/HIGH

false/LOW

Implements GpioExpanderAdapter.

update()

void AdafruitPCF8574ExpanderAdapter::update ( )

inlineoverridevirtual

Update the state of all input pins (called from loop() before updating EventButtons)

Implements GpioExpanderAdapter.

updateAndRead()

bool AdafruitPCF8574ExpanderAdapter::updateAndRead ( byte  pin )

inline

Update the expander over I2C and return a pin state. Not recommended, use a single uptate() and then multiple pin read()s in loop().

Parameters

pin	The pin number on the expander board

Returns

true/HIGH

false/LOW

write()

void AdafruitPCF8574ExpanderAdapter::write ( byte  pin, bool  state  )

inline

Write bool state to a pin.

Sets the pin state directlu over I2C

Parameters

pin	The pin number on the expander
state	true/false or HIGH/LOW

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

• src/GpioExpanderAdapter/AdafruitPCF8574ExpanderAdapter.h