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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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