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