blob: 49b84ee0e89836b7647ac946b723a226608d50d6 (
plain) (
blame)
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
|
// Simple analog to digitial conversion
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <stdint.h>
#include "analog.h"
static uint8_t aref = (1<<REFS0); // default to AREF = Vcc
void analogReference(uint8_t mode)
{
aref = mode & 0xC0;
}
// Arduino compatible pin input
int16_t analogRead(uint8_t pin)
{
#if defined(__AVR_ATmega32U4__)
static const uint8_t PROGMEM pin_to_mux[] = {
0x00, 0x01, 0x04, 0x05, 0x06, 0x07,
0x25, 0x24, 0x23, 0x22, 0x21, 0x20};
if (pin >= 12) return 0;
return adc_read(pgm_read_byte(pin_to_mux + pin));
#elif defined(__AVR_AT90USB646__) || defined(__AVR_AT90USB1286__)
if (pin >= 8) return 0;
return adc_read(pin);
#else
return 0;
#endif
}
// Mux input
int16_t adc_read(uint8_t mux)
{
#if defined(__AVR_AT90USB162__)
return 0;
#else
uint8_t low;
ADCSRA = (1<<ADEN) | ADC_PRESCALER; // enable ADC
ADCSRB = (1<<ADHSM) | (mux & 0x20); // high speed mode
ADMUX = aref | (mux & 0x1F); // configure mux input
ADCSRA = (1<<ADEN) | ADC_PRESCALER | (1<<ADSC); // start the conversion
while (ADCSRA & (1<<ADSC)) ; // wait for result
low = ADCL; // must read LSB first
return (ADCH << 8) | low; // must read MSB only once!
#endif
}
|
