Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

138 lines (112 sloc) 3.424 kb
#include "analog.h"
/** \file
\brief Analog subsystem
*/
#include "temp.h"
#include <avr/interrupt.h>
#include "memory_barrier.h"
/* OR-combined mask of all channels */
#undef DEFINE_TEMP_SENSOR
//! automagically generate analog_mask from DEFINE_TEMP_SENSOR entries in config.h
#define DEFINE_TEMP_SENSOR(name, type, pin, additional) \
| (((type == TT_THERMISTOR) || (type == TT_AD595)) ? (1 << (pin ## _ADC)) : 0)
#ifdef AIO8_PIN
static const uint16_t analog_mask = 0
#else
static const uint8_t analog_mask = 0
#endif
#include "config.h"
;
#undef DEFINE_TEMP_SENSOR
static uint8_t adc_counter;
static volatile uint16_t adc_result[NUM_TEMP_SENSORS] __attribute__ ((__section__ (".bss")));
#define DEFINE_TEMP_SENSOR(name, type, pin, additional) \
((type == TT_THERMISTOR) || (type == TT_AD595)) ? (pin ## _ADC) : 255,
static uint8_t adc_channel[NUM_TEMP_SENSORS] =
{
#include "config.h"
};
#undef DEFINE_TEMP_SENSOR
//! Configure all registers, start interrupt loop
void analog_init() {
if (analog_mask > 0) {
// clear ADC bit in power reduction register because of ADC use.
#ifdef PRR
PRR &= ~MASK(PRADC);
#elif defined PRR0
PRR0 &= ~MASK(PRADC);
#endif
// select reference signal to use, set right adjusted results and select ADC input 0
ADMUX = REFERENCE;
// ADC frequency must be less than 200khz or we lose precision. At 16MHz system clock, we must use the full prescale value of 128 to get an ADC clock of 125khz.
ADCSRA = MASK(ADEN) | MASK(ADPS2) | MASK(ADPS1) | MASK(ADPS0);
#ifdef ADCSRB
ADCSRB = 0;
#endif
adc_counter = 0;
// clear analog inputs in the data direction register(s)
AIO0_DDR &= ~analog_mask;
#ifdef AIO8_DDR
AIO8_DDR &= ~(analog_mask >> 8);
#endif
// disable the analog inputs for digital use.
DIDR0 = analog_mask & 0xFF;
#ifdef DIDR2
DIDR2 = (analog_mask >> 8) & 0xFF;
#endif
// now we start the first conversion and leave the rest to the interrupt
ADCSRA |= MASK(ADIE) | MASK(ADSC);
} /* analog_mask > 0 */
}
/*! Analog Interrupt
This is where we read our analog value and store it in an array for later retrieval
*/
ISR(ADC_vect, ISR_NOBLOCK) {
// save status register
uint8_t sreg_save = SREG;
// emulate free-running mode but be more deterministic about exactly which result we have, since this project has long-running interrupts
if (analog_mask > 0) { // at least one temp sensor uses an analog channel
// store next result
adc_result[adc_counter] = ADC;
// next channel
do {
adc_counter++;
if (adc_counter >= sizeof(adc_channel))
adc_counter = 0;
} while (adc_channel[adc_counter] == 255);
// start next conversion
ADMUX = (adc_channel[adc_counter] & 0x07) | REFERENCE;
#ifdef MUX5
if (adc_channel[adc_counter] & 0x08)
ADCSRB |= MASK(MUX5);
else
ADCSRB &= ~MASK(MUX5);
#endif
// After the mux has been set, start a new conversion
ADCSRA |= MASK(ADSC);
}
// restore status register
MEMORY_BARRIER();
SREG = sreg_save;
}
/*! Read analog value from saved result array
\param channel Channel to be read
\return analog reading, 10-bit right aligned
*/
uint16_t analog_read(uint8_t index) {
if (analog_mask > 0) {
uint16_t r;
uint8_t sreg;
// save interrupt flag
sreg = SREG;
// disable interrupts
cli();
// atomic 16-bit copy
r = adc_result[index];
// restore interrupt flag
SREG = sreg;
return r;
} else {
return 0;
}
}
Jump to Line
Something went wrong with that request. Please try again.