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/*
* fsm-adc.c: ADC (voltage, temperature) functions for SpaghettiMonster.
*
* Copyright (C) 2017 Selene ToyKeeper
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef FSM_ADC_C
#define FSM_ADC_C
inline void ADC_on()
{
// read voltage on VCC by default
// disable digital input on VCC pin to reduce power consumption
//DIDR0 |= (1 << ADC_DIDR); // FIXME: unsure how to handle for VCC pin
// VCC / 1.1V reference
ADMUX = ADMUX_VCC;
// enable, start, prescale
ADCSRA = (1 << ADEN) | (1 << ADSC) | ADC_PRSCL;
}
inline void ADC_off() {
ADCSRA &= ~(1<<ADEN); //ADC off
}
// TODO: is this better done in main() or WDT()?
ISR(ADC_vect) {
static uint8_t adc_step = 0;
#ifdef USE_LVP
#ifdef USE_LVP_AVG
#define NUM_VOLTAGE_VALUES 4
static int16_t voltage_values[NUM_VOLTAGE_VALUES];
#endif
static uint8_t lvp_timer = 0;
static uint8_t lvp_lowpass = 0;
#define LVP_TIMER_START 50 // ticks between LVP warnings
#define LVP_LOWPASS_STRENGTH 4
#endif
#ifdef USE_THERMAL_REGULATION
#define NUM_THERMAL_VALUES 4
#define ADC_STEPS 4
static int16_t temperature_values[NUM_THERMAL_VALUES];
#else
#define ADC_STEPS 2
#endif
uint16_t measurement = ADC; // latest 10-bit ADC reading
adc_step = (adc_step + 1) & (ADC_STEPS-1);
#ifdef USE_LVP
// voltage
if (adc_step == 1) {
#ifdef USE_LVP_AVG
// prime on first execution
if (voltage == 0) {
for(uint8_t i=0; i<NUM_VOLTAGE_VALUES; i++)
voltage_values[i] = measurement;
voltage = 42; // Life, the Universe, and Everything (*)
} else {
uint16_t total = 0;
uint8_t i;
for(i=0; i<NUM_VOLTAGE_VALUES-1; i++) {
voltage_values[i] = voltage_values[i+1];
total += voltage_values[i];
}
voltage_values[i] = measurement;
total += measurement;
total = total >> 2;
voltage = (uint16_t)(1.1*1024*10)/total + VOLTAGE_FUDGE_FACTOR;
}
#else // no USE_LVP_AVG
// calculate actual voltage: volts * 10
// ADC = 1.1 * 1024 / volts
// volts = 1.1 * 1024 / ADC
voltage = (uint16_t)(1.1*1024*10)/measurement + VOLTAGE_FUDGE_FACTOR;
#endif
// if low, callback EV_voltage_low / EV_voltage_critical
// (but only if it has been more than N ticks since last call)
if (lvp_timer) {
lvp_timer --;
} else { // it has been long enough since the last warning
if (voltage < VOLTAGE_LOW) {
if (lvp_lowpass < LVP_LOWPASS_STRENGTH) {
lvp_lowpass ++;
} else {
// try to send out a warning
//uint8_t err = emit(EV_voltage_low, 0);
//uint8_t err = emit_now(EV_voltage_low, 0);
emit(EV_voltage_low, 0);
//if (!err) {
// on successful warning, reset counters
lvp_timer = LVP_TIMER_START;
lvp_lowpass = 0;
//}
}
} else {
// voltage not low? reset count
lvp_lowpass = 0;
}
}
}
#endif // ifdef USE_LVP
// TODO: temperature
// start another measurement for next time
#ifdef USE_THERMAL_REGULATION
#ifdef USE_LVP
if (adc_step < 2) ADMUX = ADMUX_VCC;
else ADMUX = ADMUX_THERM;
#else
ADMUX = ADMUX_THERM;
#endif
#else
#ifdef USE_LVP
ADMUX = ADMUX_VCC;
#endif
#endif
}
#endif
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