Initial Arduino IDE based on Processing.

build/shared/lib/avrlib/a2d.c

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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/signal.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;
+}
+