PCF8574 Class Reference

#include <PCF8574.hh>

Inheritance diagram for PCF8574:

Collaboration diagram for PCF8574:

Public Member Functions
	PCF8574 (uint8_t subaddr=7)
bool	data_direction (uint8_t ddr)
bool	input_pin (uint8_t pin)
bool	output_pin (uint8_t pin)
bool	read (uint8_t pin)
uint8_t	read ()
bool	write (uint8_t pin, uint8_t value)
bool	write (uint8_t value)
bool	write (void *buf, size_t size)

Protected Member Functions
	PCF8574 (uint8_t addr, uint8_t subaddr)

Protected Attributes
uint8_t	m_ddr
uint8_t	m_port

Static Protected Attributes
static const uint8_t	PIN_MASK = 0x07

Private Member Functions
bool	is_async () const
void	sync_request ()
void	async_request ()
virtual void	on_completion (uint8_t type, int count)

Private Attributes
uint8_t	m_addr
bool	m_async

Detailed Description

Driver for the PCF8574/PCF8574A Remote 8-bit I/O expander for I2C-bus with interrupt.

Circuit

The I/0 expander used for LCD 1602 I2C communication.

                         PCF8574A
                      +------------+
(GND)---[ ]---------1-|A0       VCC|-16--------------(VCC)
(GND)---[ ]---------2-|A1       SDA|-15-----------(SDA/A4)
(GND)---[ ]---------3-|A2       SCL|-14-----------(SCL/A5)
(P0)----------------4-|P0       INT|-13
(P1)----------------5-|P1        P7|-12---------------(P7)
(P2)----------------6-|P2        P6|-11---------------(P6)
(P3)----------------7-|P3        P5|-10---------------(P5)
(GND)---------------8-|GND       P4|-9----------------(P4)
                      +------------+

References

1. NXP Semiconductors Product data sheet, Rev. 5, 27 May 2013.

Definition at line 49 of file PCF8574.hh.

Constructor & Destructor Documentation

PCF8574::PCF8574 ( uint8_t  subaddr = 7 )

inline

Construct connection to PCF8574 Remote 8-bit I/O expander with given sub-address.

Parameters

[in]

subaddr

sub-address (0..7, default 7).

Definition at line 56 of file PCF8574.hh.

PCF8574::PCF8574 ( uint8_t  addr, uint8_t  subaddr  )

inlineprotected

Construct connection to PCF8574 Remote 8-bit I/O expander with given address.

Parameters

[in]	addr	bus address.
[in]	subaddr	device sub address.

Definition at line 151 of file PCF8574.hh.

Member Function Documentation

bool PCF8574::data_direction

(

uint8_t

ddr

)

Set data direction for port pin P0..P7; 0 for output, 1 for input. Return true if set otherwise false.

Parameters

[in]

ddr

data direction mask.

Returns

bool.

Definition at line 24 of file PCF8574.cpp.

bool PCF8574::input_pin ( uint8_t  pin )

inline

Set given pin as input. Return true if set otherwise false.

Parameters

[in]

pin

number (0..7).

Returns

bool.

Definition at line 75 of file PCF8574.hh.

bool PCF8574::output_pin ( uint8_t  pin )

inline

Set given pin as output. Return true if set otherwise false.

Parameters

[in]

pin

number (0..7).

Returns

bool.

Definition at line 86 of file PCF8574.hh.

bool PCF8574::read ( uint8_t  pin )

inline

Read given pin and return true is set otherwise false.

Parameters

[in]

pin

number (0..7).

Returns

bool.

Definition at line 97 of file PCF8574.hh.

uint8_t PCF8574::read

(

)

Read pins and return current values.

Returns

input pin values.

Definition at line 35 of file PCF8574.cpp.

bool PCF8574::write	(	uint8_t	pin,
		uint8_t	value
	)

Write set given output pin if value is non-zero, otherwise clear. Return true if successful otherwise false.

Parameters

[in]	pin	number (0..7).
[in]	value.

Returns

bool.

Definition at line 45 of file PCF8574.cpp.

bool PCF8574::write

(

uint8_t

value

)

Write given value to the output pins. Return true if successful otherwise false. Return true if successful otherwise false.

Parameters

[in]

value.

Returns

bool.

Definition at line 59 of file PCF8574.cpp.

bool PCF8574::write	(	void *	buf,
		size_t	size
	)

Write given values to the output pins. Return true if successful otherwise false. Return true if successful otherwise false.

Parameters

[in]	buf	pointer to data to write to device.
[in]	size	of buffer.

Returns

bool.

Definition at line 69 of file PCF8574.cpp.

Member Data Documentation

uint8_t PCF8574::m_ddr

protected

Data Direction Register, 0 = output, 1 = input, default all input.

Definition at line 140 of file PCF8574.hh.

uint8_t PCF8574::m_port

protected

Port Register to mask and maintain output pin values.

Definition at line 143 of file PCF8574.hh.

const uint8_t PCF8574::PIN_MASK = 0x07

staticprotected

Pin number mask.

Definition at line 137 of file PCF8574.hh.

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

• libraries/PCF8574/PCF8574.hh
• libraries/PCF8574/PCF8574.cpp