PCF8574 8-bit I/O expander for I²C bus

Detailed Description

This class implements a PCF8574 8-bit I/O expander for I²C bus.

Header file:

#include <hwa/ext/pcf8574.h>

Relatives

• (PCF,p): the single pin of the PCF at position p (0 to 7);
• (PCF,n,p): n consecutive pins of the PCF starting at position p.

Interface

• define a PCF8574 device

  You must provide:

  • the name of the TWI interface the object is connected to;
  • the slave address of the object.

  
  Example:

#define PCF          HW_PCF8574( interface, twi0, address, 0x27 )

The implementation of this device focuses on code size rather than on speed, so it relies on extern C functions. These functions are declared with HW_DECLARE(...) and defined with HW_IMPLEMENT(...):

HW_DECLARE( PCF );         // Declare the functions that implement the device

HW_IMPLEMENT( PCF );       // Define the functions that implement the device

Constructor for PCF8574

• configure the device:

hw|hwa( configure, PCF );

• get the state of output pins:

hw( read, PCF );

• set the state of output pins:

hw( write, PCF, value );

Modules
	PCF8574 I/O