a2d.h

Go to the documentation of this file.

/*! \file a2d.h \brief Analog-to-Digital converter function library. */
//*****************************************************************************
//
// File Name    : 'a2d.h'
// Title        : Analog-to-digital converter functions
// Author       : Pascal Stang - Copyright (C) 2002
// Created      : 4/08/2002
// Revised      : 4/30/2002
// 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
//
/// \ingroup driver_avr
/// \defgroup a2d A/D Converter Function Library (a2d.c)
/// \code #include "a2d.h" \endcode
/// \par Overview
///     This library provides an easy interface to the analog-to-digital
///     converter available on many AVR processors.  Updated to support
///     the ATmega128.
//
//****************************************************************************
//@{

#ifndef A2D_H
#define A2D_H

// defines

// A2D clock prescaler select
//      *selects how much the CPU clock frequency is divided
//      to create the A2D clock frequency
//      *lower division ratios make conversion go faster
//      *higher division ratios make conversions more accurate
#define ADC_PRESCALE_DIV2       0x00    ///< 0x01,0x00 -> CPU clk/2
#define ADC_PRESCALE_DIV4       0x02    ///< 0x02 -> CPU clk/4
#define ADC_PRESCALE_DIV8       0x03    ///< 0x03 -> CPU clk/8
#define ADC_PRESCALE_DIV16      0x04    ///< 0x04 -> CPU clk/16
#define ADC_PRESCALE_DIV32      0x05    ///< 0x05 -> CPU clk/32
#define ADC_PRESCALE_DIV64      0x06    ///< 0x06 -> CPU clk/64
#define ADC_PRESCALE_DIV128     0x07    ///< 0x07 -> CPU clk/128
// default value
#define ADC_PRESCALE            ADC_PRESCALE_DIV64
// do not change the mask value
#define ADC_PRESCALE_MASK       0x07

// A2D voltage reference select
//      *this determines what is used as the
//      full-scale voltage point for A2D conversions
#define ADC_REFERENCE_AREF      0x00    ///< 0x00 -> AREF pin, internal VREF turned off
#define ADC_REFERENCE_AVCC      0x01    ///< 0x01 -> AVCC pin, internal VREF turned off
#define ADC_REFERENCE_RSVD      0x02    ///< 0x02 -> Reserved
#define ADC_REFERENCE_256V      0x03    ///< 0x03 -> Internal 2.56V VREF
// default value
#define ADC_REFERENCE           ADC_REFERENCE_AVCC
// do not change the mask value
#define ADC_REFERENCE_MASK      0xC0

// bit mask for A2D channel multiplexer
#define ADC_MUX_MASK            0x1F

// channel defines (for reference and use in code)
// these channels supported by all AVRs with A2D
#define ADC_CH_ADC0             0x00
#define ADC_CH_ADC1             0x01
#define ADC_CH_ADC2             0x02
#define ADC_CH_ADC3             0x03
#define ADC_CH_ADC4             0x04
#define ADC_CH_ADC5             0x05
#define ADC_CH_ADC6             0x06
#define ADC_CH_ADC7             0x07
#define ADC_CH_122V             0x1E    ///< 1.22V voltage reference
#define ADC_CH_AGND             0x1F    ///< AGND
// these channels supported only in ATmega128
// differential with gain
#define ADC_CH_0_0_DIFF10X      0x08
#define ADC_CH_1_0_DIFF10X      0x09
#define ADC_CH_0_0_DIFF200X     0x0A
#define ADC_CH_1_0_DIFF200X     0x0B
#define ADC_CH_2_2_DIFF10X      0x0C
#define ADC_CH_3_2_DIFF10X      0x0D
#define ADC_CH_2_2_DIFF200X     0x0E
#define ADC_CH_3_2_DIFF200X     0x0F
// differential
#define ADC_CH_0_1_DIFF1X       0x10
#define ADC_CH_1_1_DIFF1X       0x11
#define ADC_CH_2_1_DIFF1X       0x12
#define ADC_CH_3_1_DIFF1X       0x13
#define ADC_CH_4_1_DIFF1X       0x14
#define ADC_CH_5_1_DIFF1X       0x15
#define ADC_CH_6_1_DIFF1X       0x16
#define ADC_CH_7_1_DIFF1X       0x17

#define ADC_CH_0_2_DIFF1X       0x18
#define ADC_CH_1_2_DIFF1X       0x19
#define ADC_CH_2_2_DIFF1X       0x1A
#define ADC_CH_3_2_DIFF1X       0x1B
#define ADC_CH_4_2_DIFF1X       0x1C
#define ADC_CH_5_2_DIFF1X       0x1D

// compatibility for new Mega processors
// ADCSR hack apparently no longer necessary in new AVR-GCC
#ifdef ADCSRA
#ifndef ADCSR
    #define ADCSR   ADCSRA
#endif
#endif
#ifdef ADATE
    #define ADFR    ADATE
#endif

// function prototypes

//! Initializes the A/D converter.
/// Turns ADC on and prepares it for use.
void a2dInit(void);

//! Turn off A/D converter
void a2dOff(void);

//! Sets the division ratio of the A/D converter clock.
/// This function is automatically called from a2dInit()
/// with a default value.
void a2dSetPrescaler(unsigned char prescale);

//! Configures which voltage reference the A/D converter uses.
/// This function is automatically called from a2dInit()
/// with a default value.
void a2dSetReference(unsigned char ref);

//! sets the a2d input channel
void a2dSetChannel(unsigned char ch);

//! start a conversion on the current a2d input channel
void a2dStartConvert(void);

//! return TRUE if conversion is complete
u08 a2dIsComplete(void);

//! Starts a conversion on A/D channel# ch,
/// returns the 10-bit value of the conversion when it is finished.
unsigned short a2dConvert10bit(unsigned char ch);

//! Starts a conversion on A/D channel# ch,
/// returns the 8-bit value of the conversion when it is finished.
unsigned char a2dConvert8bit(unsigned char ch);

#endif
//@}

---