AdafruitMCP23017ExpanderAdapter Class Reference

Description

An implementation of the GpioExpanderAdapter For Adafruit's MCP23017 library.

Details: https://learn.adafruit.com/adafruit-mcp23017-i2c-gpio-expander *

#include <AdafruitMCP23017ExpanderAdapter.h>

Inheritance diagram for AdafruitMCP23017ExpanderAdapter:

Public Member Functions
	AdafruitMCP23017ExpanderAdapter ()
	Construct a AdafruitMCP23017ExpanderAdapter. An Adafruit_MCP23X17 instance will be created for you. More...
	AdafruitMCP23017ExpanderAdapter (Adafruit_MCP23X17 &_mcp)
	Construct a AdafruitMCP23017ExpanderAdapter with an already created Adafruit_MCP23X17 instance. More...
void	begin () override
	The default begin for a GPIOExpanderAdapter will use the default I2C address for the MCP23017. 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 MCP23017 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

AdafruitMCP23017ExpanderAdapter() [1/2]

AdafruitMCP23017ExpanderAdapter::AdafruitMCP23017ExpanderAdapter ( )

inline

Construct a AdafruitMCP23017ExpanderAdapter. An Adafruit_MCP23X17 instance will be created for you.

This will create and Adafruit_MCP23017 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 begin().

AdafruitMCP23017ExpanderAdapter() [2/2]

AdafruitMCP23017ExpanderAdapter::AdafruitMCP23017ExpanderAdapter ( Adafruit_MCP23X17 &  _mcp )

inline

Construct a AdafruitMCP23017ExpanderAdapter with an already created Adafruit_MCP23X17 instance.

Parameters

_mcp

Member Function Documentation

attachPin()

void AdafruitMCP23017ExpanderAdapter::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 AdafruitMCP23017ExpanderAdapter::begin ( void  )

inlineoverridevirtual

The default begin for a GPIOExpanderAdapter will use the default I2C address for the MCP23017.

Implements GpioExpanderAdapter.

begin() [2/2]

bool AdafruitMCP23017ExpanderAdapter::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 MCP23017
wire	Optional

Returns

true

false

canWrite()

bool AdafruitMCP23017ExpanderAdapter::canWrite ( )

inline

The MCP23017 can write a pins state.

Returns

true

read()

bool AdafruitMCP23017ExpanderAdapter::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 AdafruitMCP23017ExpanderAdapter::update ( )

inlineoverridevirtual

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

Implements GpioExpanderAdapter.

updateAndRead()

bool AdafruitMCP23017ExpanderAdapter::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 AdafruitMCP23017ExpanderAdapter::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/AdafruitMCP23017ExpanderAdapter.h