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140 lines
3.2 KiB
140 lines
3.2 KiB
/**
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* High voltage source control logic
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*/
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#include "high_voltage.h"
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#include "iopins.h"
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#include "global_state.h"
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#include <stdbool.h>
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#include <avr/interrupt.h>
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#include <util/atomic.h>
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static volatile bool is_pwm_on = false;
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// tube starting voltage is 350V
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#define TURN_ON_VOLTAGE 360.0
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#define TURN_OFF_VOLTAGE 390.0
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#define MINIMAL_VOLTAGE 350.0
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// sensing via resistive divider
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#define VREF 1.1
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// in kiloohms
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#define R_UPPER 10000.0
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#define R_LOWER 27.0
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#define ADC_MAXVAL 1023
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#define RDIV_FACTOR (R_LOWER / (R_UPPER + R_LOWER))
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/// ADC input voltage that's too low - PWM must start
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#define VSEN_TURN_ON (TURN_ON_VOLTAGE * RDIV_FACTOR)
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/// ADC input voltage that's too high - PWM must stop
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#define VSEN_TURN_OFF (TURN_OFF_VOLTAGE * RDIV_FACTOR)
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/// ADC input voltage that's lowest possible for the geiger tube to function
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#define VSEN_MINIMAL (MINIMAL_VOLTAGE * RDIV_FACTOR)
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// the above, but converted to ADC word
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#define ADCVAL_TURN_ON ((uint16_t) (ADC_MAXVAL * (VSEN_TURN_ON / VREF)))
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#define ADCVAL_TURN_OFF ((uint16_t) (ADC_MAXVAL * (VSEN_TURN_OFF / VREF)))
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#define ADCVAL_MINIMAL ((uint16_t) (ADC_MAXVAL * (VSEN_MINIMAL / VREF)))
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/// Channel used to measure VSEN
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#define VSEN_ADC_CHANNEL 0
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/// when capacitor was last fully charged
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static volatile uint16_t ts_cap_charged = 0;
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static void pwm_on()
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{
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TCCR0A |= _BV(COM0B1);
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is_pwm_on = true;
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}
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static void pwm_off()
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{
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TCCR0A &= ~_BV(COM0B1);
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is_pwm_on = false;
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}
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ISR(ADC_vect)
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{
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// Service the boost converter
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uint16_t analog = ADCW;
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if (is_pwm_on) {
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if (analog >= ADCVAL_TURN_OFF) {
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pwm_off();
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ts_cap_charged = timestamp_100ms;
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} else {
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// If fail to reach target voltage in reasonable time,
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// show weak battery icon and stop trying.
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if ((timestamp_100ms - ts_cap_charged) > 10 && analog < ADCVAL_MINIMAL) {
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status_weak_battery = true;
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}
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}
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} else if (analog < ADCVAL_TURN_ON) {
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pwm_on();
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}
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}
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static void init_pwm_out()
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{
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// Output is OC0A
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as_output(D5);
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// initialize the timer
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// Fast PWM mode, Output to OC0A
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// clock is 16MHz, presc /64, counting to 80 -> freq 3125Hz
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// Duty cycle = appx. 60%
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OCR0A = 80;
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OCR0B = 46;
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TCCR0A = _BV(WGM00) | _BV(WGM01);
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TCCR0B = _BV(CS01) | _BV(CS00) | _BV(WGM02);
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}
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static void init_adc()
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{
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ADCSRA =
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// 128 prescaler -> 125 kHz
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_BV(ADPS2) | _BV(ADPS1) | _BV(ADPS0)
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// auto trigger
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| _BV(ADATE)
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// interrupt enable
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| _BV(ADIE);
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ADCSRB = 0; // free-running
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DIDR0 = ADC0D; // disable the digital input buffer on the pin
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ADMUX =
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// internal ref 1.1V
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_BV(REFS0) | _BV(REFS1)
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// select channel
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| VSEN_ADC_CHANNEL;
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sbi(ADCSRA, ADEN); // Enable ADC
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sbi(ADCSRA, ADSC); // Start
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}
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void init_high_voltage()
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{
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init_pwm_out();
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init_adc();
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}
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void hv_disable()
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{
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ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
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// if ADC is disabled, the IRQ never fires and it won't be turned on
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cbi(ADCSRA, ADEN);
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// Turn it off
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pwm_off();
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}
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}
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