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a2d.h

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//*****************************************************************************
//
// 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  : 3
//
// This code is distributed under the GNU Public License
//              which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

#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
// 0x00 -> CPU clk/2
// 0x01 -> CPU clk/2
// 0x02 -> CPU clk/4
// 0x03 -> CPU clk/8
// 0x04 -> CPU clk/16
// 0x05 -> CPU clk/32
// 0x06 -> CPU clk/64
// 0x07 -> CPU clk/128
#define ADC_PRESCALE                    0x06
// 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
// 0x00 -> AREF pin, internal VREF turned off
// 0x01 -> AVCC pin, internal VREF turned off
// 0x02 -> Reserved
// 0x03 -> Internal 2.56V VREF
#define ADC_REFERENCE           0x01
// 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)
// 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

// 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);

// starts a conversion on A/D channel# ch,
// returns the value of the conversion when it is finished
unsigned short a2dConvert10bit(unsigned char ch);
unsigned char a2dConvert8bit(unsigned char ch);

#endif

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