summaryrefslogtreecommitdiffstats
path: root/drivers/avr/analog.c
blob: 9b8397b933f32da863e8cc777a841c21bd0edebb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
/* Copyright 2015 Jack Humbert
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <avr/io.h>
#include <avr/pgmspace.h>
#include <stdint.h>
#include "analog.h"

static uint8_t aref = ADC_REF_POWER;

void analogReference(uint8_t mode) { aref = mode & (_BV(REFS1) | _BV(REFS0)); }

// Arduino compatible pin input
int16_t analogRead(uint8_t pin) {
#if defined(__AVR_ATmega32U4__)
    // clang-format off
    static const uint8_t PROGMEM pin_to_mux[] = {
        //A0    A1    A2    A3    A4    A5
        //F7    F6    F5    F4    F1    F0
        0x07, 0x06, 0x05, 0x04, 0x01, 0x00,
        //A6    A7    A8    A9   A10   A11
        //D4    D7    B4    B5    B6    D6
        0x20, 0x22, 0x23, 0x24, 0x25, 0x21
    };
    // clang-format on
    if (pin >= 12) return 0;
    return adc_read(pgm_read_byte(pin_to_mux + pin));
#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__) || defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)
    if (pin >= 8) return 0;
    return adc_read(pin);
#else
    return 0;
#endif
}

int16_t analogReadPin(pin_t pin) { return adc_read(pinToMux(pin)); }

uint8_t pinToMux(pin_t pin) {
    switch (pin) {
        // clang-format off
#if defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
        case F0: return 0;  // ADC0
        case F1: return _BV(MUX0);  // ADC1
        case F2: return _BV(MUX1);  // ADC2
        case F3: return _BV(MUX1) | _BV(MUX0);  // ADC3
        case F4: return _BV(MUX2);  // ADC4
        case F5: return _BV(MUX2) | _BV(MUX0);  // ADC5
        case F6: return _BV(MUX2) | _BV(MUX1);  // ADC6
        case F7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0);  // ADC7
        default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0);  // 0V
#elif defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
        case F0: return 0;  // ADC0
        case F1: return _BV(MUX0);  // ADC1
        case F4: return _BV(MUX2);  // ADC4
        case F5: return _BV(MUX2) | _BV(MUX0);  // ADC5
        case F6: return _BV(MUX2) | _BV(MUX1);  // ADC6
        case F7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0);  // ADC7
        case D4: return _BV(MUX5);  // ADC8
        case D6: return _BV(MUX5) | _BV(MUX0);  // ADC9
        case D7: return _BV(MUX5) | _BV(MUX1);  // ADC10
        case B4: return _BV(MUX5) | _BV(MUX1) | _BV(MUX0);  // ADC11
        case B5: return _BV(MUX5) | _BV(MUX2);  // ADC12
        case B6: return _BV(MUX5) | _BV(MUX2) | _BV(MUX0);  // ADC13
        default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0);  // 0V
#elif defined(__AVR_ATmega32A__)
        case A0: return 0;  // ADC0
        case A1: return _BV(MUX0);  // ADC1
        case A2: return _BV(MUX1);  // ADC2
        case A3: return _BV(MUX1) | _BV(MUX0);  // ADC3
        case A4: return _BV(MUX2);  // ADC4
        case A5: return _BV(MUX2) | _BV(MUX0);  // ADC5
        case A6: return _BV(MUX2) | _BV(MUX1);  // ADC6
        case A7: return _BV(MUX2) | _BV(MUX1) | _BV(MUX0);  // ADC7
        default: return _BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0);  // 0V
#elif defined(__AVR_ATmega328P__) || defined(__AVR_ATmega328__)
        case C0: return 0;  // ADC0
        case C1: return _BV(MUX0);  // ADC1
        case C2: return _BV(MUX1);  // ADC2
        case C3: return _BV(MUX1) | _BV(MUX0);  // ADC3
        case C4: return _BV(MUX2);  // ADC4
        case C5: return _BV(MUX2) | _BV(MUX0);  // ADC5
        // ADC7:6 not present in DIP package and not shared by GPIO pins
        default: return _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0);  // 0V
#endif
            // clang-format on
    }
}

int16_t adc_read(uint8_t mux) {
    uint8_t low;

    // Enable ADC and configure prescaler
    ADCSRA = _BV(ADEN) | ADC_PRESCALER;

#if defined(__AVR_ATmega16U4__) || defined(__AVR_ATmega32U4__)
    // High speed mode and ADC8-13
    ADCSRB = _BV(ADHSM) | (mux & _BV(MUX5));
#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB647__) || defined(__AVR_AT90USB1286__) || defined(__AVR_AT90USB1287__)
    // High speed mode only
    ADCSRB = _BV(ADHSM);
#endif

    // Configure mux input
#if defined(MUX4)
    ADMUX = aref | (mux & (_BV(MUX4) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0)));
#else
    ADMUX  = aref | (mux & (_BV(MUX3) | _BV(MUX2) | _BV(MUX1) | _BV(MUX0)));
#endif

    // Start the conversion
    ADCSRA |= _BV(ADSC);
    // Wait for result
    while (ADCSRA & _BV(ADSC))
        ;
    // Must read LSB first
    low = ADCL;
    // Must read MSB only once!
    return (ADCH << 8) | low;
}