PCF8574 Class Reference

#include <PCF8574.h>

Inheritance diagram for PCF8574:

Collaboration diagram for PCF8574:

Classes
class	GPIO

Public Member Functions
	PCF8574 (TWI &twi, uint8_t subaddr=7)
uint8_t	ddr ()
void	ddr (uint8_t ddr)
uint8_t	read ()
uint8_t	port ()
void	write (uint8_t value)
void	write (void *buf, size_t size)

Protected Member Functions
	PCF8574 (TWI &twi, uint8_t addr, uint8_t subaddr)
bool	acquire ()
bool	release ()
int	read (void *buf, size_t count)
int	write (const void *buf, size_t count)
int	write (iovec_t *vp)

Protected Attributes
uint8_t	m_ddr
uint8_t	m_port
TWI &	m_twi
uint8_t	m_addr

Detailed Description

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

Circuit

                         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--------------(EXT)
(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 46 of file PCF8574.h.

Constructor & Destructor Documentation

PCF8574::PCF8574 ( TWI &  twi, uint8_t  subaddr = 7  )

inline

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

Parameters

[in]	twi	bus manager.
[in]	subaddr	sub-address (0..7, default 7).

Definition at line 54 of file PCF8574.h.

PCF8574::PCF8574 ( TWI &  twi, uint8_t  addr, uint8_t  subaddr  )

inlineprotected

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

Parameters

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

Definition at line 229 of file PCF8574.h.

Member Function Documentation

bool TWI::Device::acquire ( )

inlineinherited

Start transaction. Return true(1) if successful otherwise false(0).

Returns

bool.

Definition at line 52 of file TWI.h.

uint8_t PCF8574::ddr ( )

inline

Get data direction for port; 0 for output, 1 for input.

Returns

data direction.

Definition at line 64 of file PCF8574.h.

void PCF8574::ddr ( uint8_t  ddr )

inline

Set data direction for port pin P0..P7; 0 for output, 1 for input.

Parameters

[in]

ddr

data direction mask.

Definition at line 73 of file PCF8574.h.

uint8_t PCF8574::port ( )

inline

Get data port values.

Returns

port value.

Definition at line 99 of file PCF8574.h.

int TWI::Device::read ( void *  buf, size_t  count  )

inlineinherited

Read data from device to given buffer.

Parameters

[in]	buf	buffer pointer.
[in]	count	buffer size in bytes.

Returns

number of bytes read or negative error code.

Definition at line 73 of file TWI.h.

uint8_t PCF8574::read ( )

inline

Read pins and return current values.

Returns

input pin values.

Definition at line 86 of file PCF8574.h.

bool TWI::Device::release ( )

inlineinherited

Stop transaction. Return true(1) if successful otherwise false(0).

Returns

bool.

Definition at line 62 of file TWI.h.

int TWI::Device::write ( const void *  buf, size_t  count  )

inlineinherited

Write data from the given buffer to device.

Parameters

[in]	buf	buffer pointer.
[in]	count	buffer size in bytes.

Returns

number of bytes written or negative error code.

Definition at line 84 of file TWI.h.

int TWI::Device::write ( iovec_t *  vp )

inlineinherited

Write data to device with from given io vector.

Parameters

[in]

vp

io vector pointer.

Returns

number of bytes written or negative error code.

Definition at line 94 of file TWI.h.

void PCF8574::write ( uint8_t  value )

inline

Write given value to the output pins.

Parameters

[in]

value

to write to port.

Definition at line 108 of file PCF8574.h.

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

inline

Write given values to the output pins.

Parameters

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

Definition at line 121 of file PCF8574.h.

Member Data Documentation

uint8_t TWI::Device::m_addr

protectedinherited

Device address.

Definition at line 104 of file TWI.h.

uint8_t PCF8574::m_ddr

protected

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

Definition at line 217 of file PCF8574.h.

uint8_t PCF8574::m_port

protected

Port Register to mask and maintain output pin values.

Definition at line 220 of file PCF8574.h.

TWI& TWI::Device::m_twi

protectedinherited

Two-Wire Interface Manager.

Definition at line 101 of file TWI.h.

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

• src/Driver/PCF8574.h