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