Permalink
Switch branches/tags
Nothing to show
Find file
Fetching contributors…
Cannot retrieve contributors at this time
199 lines (173 sloc) 4.47 KB
// ---------------------------------------------------------------------------
// Created by Francisco Malpartida on 20/08/11.
// Copyright 2011 - Under creative commons license 3.0:
// Attribution-ShareAlike CC BY-SA
//
// This software is furnished "as is", without technical support, and with no
// warranty, express or implied, as to its usefulness for any purpose.
//
// Thread Safe: No
// Extendable: Yes
//
// @file I2CIO.h
// This file implements a basic IO library using the PCF8574 I2C IO Expander
// chip.
//
// @brief
// Implement a basic IO library to drive the PCF8574* I2C IO Expander ASIC.
// The library implements basic IO general methods to configure IO pin direction
// read and write uint8_t operations and basic pin level routines to set or read
// a particular IO port.
//
// This library is only compatible with Arduino's SDK version 1.0
//
// @version API 1.0.0
//
// @author F. Malpartida - fmalpartida@gmail.com
// ---------------------------------------------------------------------------
#if (ARDUINO < 100)
#include <WProgram.h>
#else
#include <Arduino.h>
#endif
#include <inttypes.h>
#include <Wire.h>
#include <I2CIO.h>
// CLASS VARIABLES
// ---------------------------------------------------------------------------
// CONSTRUCTOR
// ---------------------------------------------------------------------------
I2CIO::I2CIO ( )
{
_i2cAddr = 0x0;
_dirMask = 0xFF; // mark all as INPUTs
_shadow = 0x0; // no values set
_initialised = false;
}
// PUBLIC METHODS
// ---------------------------------------------------------------------------
//
// begin
int I2CIO::begin ( uint8_t i2cAddr )
{
_i2cAddr = i2cAddr;
Wire.begin ( );
_initialised = Wire.requestFrom ( _i2cAddr, (uint8_t)1 );
#if (ARDUINO < 100)
_shadow = Wire.receive ();
#else
_shadow = Wire.read (); // Remove the byte read don't need it.
#endif
return ( _initialised );
}
//
// pinMode
void I2CIO::pinMode ( uint8_t pin, uint8_t dir )
{
if ( _initialised )
{
if ( OUTPUT == dir )
{
_dirMask &= ~( 1 << pin );
}
else
{
_dirMask |= ( 1 << pin );
}
}
}
//
// portMode
void I2CIO::portMode ( uint8_t dir )
{
if ( _initialised )
{
if ( dir == INPUT )
{
_dirMask = 0xFF;
}
else
{
_dirMask = 0x00;
}
}
}
//
// read
uint8_t I2CIO::read ( void )
{
uint8_t retVal = 0;
if ( _initialised )
{
Wire.requestFrom ( _i2cAddr, (uint8_t)1 );
#if (ARDUINO < 100)
retVal = ( _dirMask & Wire.receive ( ) );
#else
retVal = ( _dirMask & Wire.read ( ) );
#endif
}
return ( retVal );
}
//
// write
int I2CIO::write ( uint8_t value )
{
int status = 0;
if ( _initialised )
{
// Only write HIGH the values of the ports that have been initialised as
// outputs updating the output shadow of the device
_shadow = ( value & ~(_dirMask) );
Wire.beginTransmission ( _i2cAddr );
#if (ARDUINO < 100)
Wire.send ( _shadow );
#else
Wire.write ( _shadow );
#endif
status = Wire.endTransmission ();
}
return ( (status == 0) );
}
//
// digitalRead
uint8_t I2CIO::digitalRead ( uint8_t pin )
{
uint8_t pinVal = 0;
// Check if initialised and that the pin is within range of the device
// -------------------------------------------------------------------
if ( ( _initialised ) && ( pin <= 7 ) )
{
// Remove the values which are not inputs and get the value of the pin
pinVal = this->read() & _dirMask;
pinVal = ( pinVal >> pin ) & 0x01; // Get the pin value
}
return (pinVal);
}
//
// digitalWrite
int I2CIO::digitalWrite ( uint8_t pin, uint8_t level )
{
uint8_t writeVal;
int status = 0;
// Check if initialised and that the pin is within range of the device
// -------------------------------------------------------------------
if ( ( _initialised ) && ( pin <= 7 ) )
{
// Only write to HIGH the port if the port has been configured as
// an OUTPUT pin. Add the new state of the pin to the shadow
writeVal = ( 1 << pin ) & ~_dirMask;
if ( level == HIGH )
{
_shadow |= writeVal;
}
else
{
_shadow &= ~writeVal;
}
status = this->write ( _shadow );
}
return ( status );
}
//
// PRIVATE METHODS
// ---------------------------------------------------------------------------