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/*! \file a2d.c \brief Analog-to-Digital converter function library. */
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//*****************************************************************************
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//
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// File Name	: 'a2d.c'
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// Title		: Analog-to-digital converter functions
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// Author		: Pascal Stang - Copyright (C) 2002
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// Created		: 2002-04-08
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// Revised		: 2002-09-30
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// Version		: 1.1
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// Target MCU	: Atmel AVR series
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// Editor Tabs	: 4
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//
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// This code is distributed under the GNU Public License
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//		which can be found at http://www.gnu.org/licenses/gpl.txt
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//
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//*****************************************************************************
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include "global.h"
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#include "a2d.h"
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// global variables
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//! Software flag used to indicate when
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/// the a2d conversion is complete.
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volatile unsigned char a2dCompleteFlag;
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// functions
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// initialize a2d converter
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void a2dInit(void)
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{
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	sbi(ADCSR, ADEN);				// enable ADC (turn on ADC power)
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	cbi(ADCSR, ADFR);				// default to single sample convert mode
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	a2dSetPrescaler(ADC_PRESCALE);	// set default prescaler
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	a2dSetReference(ADC_REFERENCE);	// set default reference
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	cbi(ADMUX, ADLAR);				// set to right-adjusted result
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	sbi(ADCSR, ADIE);				// enable ADC interrupts
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	a2dCompleteFlag = FALSE;		// clear conversion complete flag
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	sei();							// turn on interrupts (if not already on)
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}
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// turn off a2d converter
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void a2dOff(void)
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{
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	cbi(ADCSR, ADIE);				// disable ADC interrupts
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	cbi(ADCSR, ADEN);				// disable ADC (turn off ADC power)
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}
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// configure A2D converter clock division (prescaling)
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void a2dSetPrescaler(unsigned char prescale)
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{
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	outb(ADCSR, ((inb(ADCSR) & ~ADC_PRESCALE_MASK) | prescale));
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}
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// configure A2D converter voltage reference
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void a2dSetReference(unsigned char ref)
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{
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	outb(ADMUX, ((inb(ADMUX) & ~ADC_REFERENCE_MASK) | (ref<<6)));
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}
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// sets the a2d input channel
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void a2dSetChannel(unsigned char ch)
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{
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	outb(ADMUX, (inb(ADMUX) & ~ADC_MUX_MASK) | (ch & ADC_MUX_MASK));	// set channel
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}
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// start a conversion on the current a2d input channel
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void a2dStartConvert(void)
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{
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	sbi(ADCSR, ADIF);	// clear hardware "conversion complete" flag 
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	sbi(ADCSR, ADSC);	// start conversion
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}
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// return TRUE if conversion is complete
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u08 a2dIsComplete(void)
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{
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	return bit_is_set(ADCSR, ADSC);
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}
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// Perform a 10-bit conversion
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// starts conversion, waits until conversion is done, and returns result
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unsigned short a2dConvert10bit(unsigned char ch)
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{
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	a2dCompleteFlag = FALSE;				// clear conversion complete flag
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	outb(ADMUX, (inb(ADMUX) & ~ADC_MUX_MASK) | (ch & ADC_MUX_MASK));	// set channel
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	sbi(ADCSR, ADIF);						// clear hardware "conversion complete" flag 
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	sbi(ADCSR, ADSC);						// start conversion
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	//while(!a2dCompleteFlag);				// wait until conversion complete
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	//while( bit_is_clear(ADCSR, ADIF) );		// wait until conversion complete
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	while( bit_is_set(ADCSR, ADSC) );		// wait until conversion complete
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	// CAUTION: MUST READ ADCL BEFORE ADCH!!!
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	return (inb(ADCL) | (inb(ADCH)<<8));	// read ADC (full 10 bits);
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}
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// Perform a 8-bit conversion.
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// starts conversion, waits until conversion is done, and returns result
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unsigned char a2dConvert8bit(unsigned char ch)
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{
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	// do 10-bit conversion and return highest 8 bits
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	return a2dConvert10bit(ch)>>2;			// return ADC MSB byte
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}
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//! Interrupt handler for ADC complete interrupt.
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SIGNAL(SIG_ADC)
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{
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	// set the a2d conversion flag to indicate "complete"
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	a2dCompleteFlag = TRUE;
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}
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