You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
54 lines
1.2 KiB
54 lines
1.2 KiB
// 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
|
|
}
|
|
|
|
|