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117 lines
3.5 KiB
C
Executable File
117 lines
3.5 KiB
C
Executable File
/*! \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/signal.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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