nes-proj/platform/avr-rss2/dev/adc.c
2016-02-22 20:46:07 +01:00

77 lines
1.5 KiB
C

/* Copyright Robert Olsson */
#include <avr/pgmspace.h>
#include <avr/fuse.h>
#include <avr/eeprom.h>
#include <stdio.h>
#include <string.h>
#include <dev/watchdog.h>
#include "params.h"
#include "rss2.h"
#include "contiki.h"
#include "adc.h"
#include "rss2.h"
uint16_t
adc_read(uint8_t pin)
{
uint16_t volt = 0;
int i;
ADMUX = pin; /* ADC pin PA0-PA7 -> 0-7 */
ADCSRB &= ~(1 << MUX5); /* Needs to write before ADMUX pp 418 */
ADMUX |= (1 << REFS1) | (1 << REFS0); /* 1.6 */
/* Maximal Track and Hold time */
ADCSRA = (1 << ADPS2) | (0 << ADPS1) | (1 << ADPS0); /* Prescaler /32 */
ADCSRA |= (1 << ADEN); /* Enable the ADC */
while(!(ADCSRB & (1 << AVDDOK))) ; /* Wait for AVDD ok */
while(!(ADCSRB & (1 << REFOK))) ; /* Wait for ref ok */
/* Ignore first result */
ADCSRA |= (1 << ADSC);
while(ADCSRA & _BV(ADSC)) {
}
ADCW = 0;
#define RES 4
for(i = 0; i < RES; i++) {
/* Start the conversion */
ADCSRA |= (1 << ADSC);
/* Wait for conversion */
while(ADCSRA & (1 << ADSC)) {
}
volt += ADCW;
}
ADMUX = 0; /* turn off internal vref */
volt = volt / RES;
/* Disable the ADC to save power */
ADCSRA &= ~_BV(ADEN);
return volt;
}
double
adc_read_v_in(void)
{
/* Special treatment for v_in. Schottky voltage drop add */
return ((double)adc_read(AV_IN)) * V_IN_FACTOR_SCHOTTKY + SCHOTTKY_DROP;
}
double
adc_read_a1(void)
{
return ((double)adc_read(A1)) * V_IN_FACTOR;
}
double
adc_read_a2(void)
{
return ((double)adc_read(A2)) * V_IN_FACTOR;
}