105 lines
2.5 KiB
C
105 lines
2.5 KiB
C
|
|
/** \file
|
|
\brief Analog subsystem, AVR specific part.
|
|
*/
|
|
|
|
#if defined TEACUP_C_INCLUDE && defined __AVR__
|
|
|
|
#include "pinio.h"
|
|
#include "memory_barrier.h"
|
|
|
|
|
|
static uint8_t adc_counter;
|
|
static volatile uint16_t BSS adc_result[NUM_TEMP_SENSORS];
|
|
|
|
//! Configure all registers, start interrupt loop
|
|
void analog_init() {
|
|
|
|
if (analog_mask) { // At least one temp sensor uses an analog channel.
|
|
// 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 */
|
|
}
|
|
|
|
/*! Analog Interrupt
|
|
|
|
This is where we read our analog value and store it in an array for later retrieval
|
|
*/
|
|
ISR(ADC_vect, ISR_NOBLOCK) {
|
|
// emulate free-running mode but be more deterministic about exactly which result we have, since this project has long-running interrupts
|
|
if (analog_mask) {
|
|
// 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);
|
|
}
|
|
}
|
|
|
|
/*! 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;
|
|
|
|
ATOMIC_START
|
|
// atomic 16-bit copy
|
|
r = adc_result[index];
|
|
ATOMIC_END
|
|
|
|
return r;
|
|
} else {
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
#endif /* defined TEACUP_C_INCLUDE && defined __AVR__ */
|