| 507 |
kaklik |
1 |
/*! \file a2d.c \brief Analog-to-Digital converter function library. */
|
|
|
2 |
//*****************************************************************************
|
|
|
3 |
//
|
|
|
4 |
// File Name : 'a2d.c'
|
|
|
5 |
// Title : Analog-to-digital converter functions
|
|
|
6 |
// Author : Pascal Stang - Copyright (C) 2002
|
|
|
7 |
// Created : 2002-04-08
|
|
|
8 |
// Revised : 2002-09-30
|
|
|
9 |
// Version : 1.1
|
|
|
10 |
// Target MCU : Atmel AVR series
|
|
|
11 |
// Editor Tabs : 4
|
|
|
12 |
//
|
|
|
13 |
// This code is distributed under the GNU Public License
|
|
|
14 |
// which can be found at http://www.gnu.org/licenses/gpl.txt
|
|
|
15 |
//
|
|
|
16 |
//*****************************************************************************
|
|
|
17 |
|
|
|
18 |
#include <avr/io.h>
|
|
|
19 |
#include <avr/interrupt.h>
|
|
|
20 |
|
|
|
21 |
#include "global.h"
|
|
|
22 |
#include "a2d.h"
|
|
|
23 |
|
|
|
24 |
// global variables
|
|
|
25 |
|
|
|
26 |
//! Software flag used to indicate when
|
|
|
27 |
/// the a2d conversion is complete.
|
|
|
28 |
volatile unsigned char a2dCompleteFlag;
|
|
|
29 |
|
|
|
30 |
// functions
|
|
|
31 |
|
|
|
32 |
// initialize a2d converter
|
|
|
33 |
void a2dInit(void)
|
|
|
34 |
{
|
|
|
35 |
sbi(ADCSR, ADEN); // enable ADC (turn on ADC power)
|
|
|
36 |
cbi(ADCSR, ADFR); // default to single sample convert mode
|
|
|
37 |
a2dSetPrescaler(ADC_PRESCALE); // set default prescaler
|
|
|
38 |
a2dSetReference(ADC_REFERENCE); // set default reference
|
|
|
39 |
cbi(ADMUX, ADLAR); // set to right-adjusted result
|
|
|
40 |
|
|
|
41 |
sbi(ADCSR, ADIE); // enable ADC interrupts
|
|
|
42 |
|
|
|
43 |
a2dCompleteFlag = FALSE; // clear conversion complete flag
|
|
|
44 |
sei(); // turn on interrupts (if not already on)
|
|
|
45 |
}
|
|
|
46 |
|
|
|
47 |
// turn off a2d converter
|
|
|
48 |
void a2dOff(void)
|
|
|
49 |
{
|
|
|
50 |
cbi(ADCSR, ADIE); // disable ADC interrupts
|
|
|
51 |
cbi(ADCSR, ADEN); // disable ADC (turn off ADC power)
|
|
|
52 |
}
|
|
|
53 |
|
|
|
54 |
// configure A2D converter clock division (prescaling)
|
|
|
55 |
void a2dSetPrescaler(unsigned char prescale)
|
|
|
56 |
{
|
|
|
57 |
outb(ADCSR, ((inb(ADCSR) & ~ADC_PRESCALE_MASK) | prescale));
|
|
|
58 |
}
|
|
|
59 |
|
|
|
60 |
// configure A2D converter voltage reference
|
|
|
61 |
void a2dSetReference(unsigned char ref)
|
|
|
62 |
{
|
|
|
63 |
outb(ADMUX, ((inb(ADMUX) & ~ADC_REFERENCE_MASK) | (ref<<6)));
|
|
|
64 |
}
|
|
|
65 |
|
|
|
66 |
// sets the a2d input channel
|
|
|
67 |
void a2dSetChannel(unsigned char ch)
|
|
|
68 |
{
|
|
|
69 |
outb(ADMUX, (inb(ADMUX) & ~ADC_MUX_MASK) | (ch & ADC_MUX_MASK)); // set channel
|
|
|
70 |
}
|
|
|
71 |
|
|
|
72 |
// start a conversion on the current a2d input channel
|
|
|
73 |
void a2dStartConvert(void)
|
|
|
74 |
{
|
|
|
75 |
sbi(ADCSR, ADIF); // clear hardware "conversion complete" flag
|
|
|
76 |
sbi(ADCSR, ADSC); // start conversion
|
|
|
77 |
}
|
|
|
78 |
|
|
|
79 |
// return TRUE if conversion is complete
|
|
|
80 |
u08 a2dIsComplete(void)
|
|
|
81 |
{
|
|
|
82 |
return bit_is_set(ADCSR, ADSC);
|
|
|
83 |
}
|
|
|
84 |
|
|
|
85 |
// Perform a 10-bit conversion
|
|
|
86 |
// starts conversion, waits until conversion is done, and returns result
|
|
|
87 |
unsigned short a2dConvert10bit(unsigned char ch)
|
|
|
88 |
{
|
|
|
89 |
a2dCompleteFlag = FALSE; // clear conversion complete flag
|
|
|
90 |
outb(ADMUX, (inb(ADMUX) & ~ADC_MUX_MASK) | (ch & ADC_MUX_MASK)); // set channel
|
|
|
91 |
sbi(ADCSR, ADIF); // clear hardware "conversion complete" flag
|
|
|
92 |
sbi(ADCSR, ADSC); // start conversion
|
|
|
93 |
//while(!a2dCompleteFlag); // wait until conversion complete
|
|
|
94 |
//while( bit_is_clear(ADCSR, ADIF) ); // wait until conversion complete
|
|
|
95 |
while( bit_is_set(ADCSR, ADSC) ); // wait until conversion complete
|
|
|
96 |
|
|
|
97 |
// CAUTION: MUST READ ADCL BEFORE ADCH!!!
|
|
|
98 |
return (inb(ADCL) | (inb(ADCH)<<8)); // read ADC (full 10 bits);
|
|
|
99 |
}
|
|
|
100 |
|
|
|
101 |
// Perform a 8-bit conversion.
|
|
|
102 |
// starts conversion, waits until conversion is done, and returns result
|
|
|
103 |
unsigned char a2dConvert8bit(unsigned char ch)
|
|
|
104 |
{
|
|
|
105 |
// do 10-bit conversion and return highest 8 bits
|
|
|
106 |
return a2dConvert10bit(ch)>>2; // return ADC MSB byte
|
|
|
107 |
}
|
|
|
108 |
|
|
|
109 |
//! Interrupt handler for ADC complete interrupt.
|
|
|
110 |
SIGNAL(SIG_ADC)
|
|
|
111 |
{
|
|
|
112 |
// set the a2d conversion flag to indicate "complete"
|
|
|
113 |
a2dCompleteFlag = TRUE;
|
|
|
114 |
}
|
|
|
115 |
|