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/*
* Simple PWM controller
* ADC measurement
*
* Copyright (c) 2018-2020 Michael Buesch <m@bues.ch>
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "compat.h"
#include "adc.h"
#include "util.h"
#include "main.h"
#include "curve.h"
#include "curve_data_adc2sp.h"
#include "pwm.h"
#include "filter.h"
#include "battery.h"
/* ADC configuration. */
#define ADC_HYST 1u /* ADC hysteresis */
#define ADC_MIN 0u /* Physical ADC minimum */
#define ADC_MAX 0x3FFu /* Physical ADC maximum */
#define ADC_VBG_MV 1100u /* Vbg in millivolts. */
#define ADC_FILTER_SHIFT 9
static struct {
struct lp_filter filter;
bool battery_meas;
uint8_t delay;
uint8_t prev_pwm_count;
} adc;
/* Configure the ADC hardware.
* Interrupts must be disabled before calling this function. */
static void adc_configure(bool enable)
{
/* Disable ADC unit. */
ADCSRA = 0;
/* Disable ADC2 digital input */
DIDR0 = (1 << ADC2D);
/* Trigger source = free running */
ADCSRB = (0 << ADTS2) | (0 << ADTS1) | (0 << ADTS0);
if (enable) {
if (adc_battery_measurement_running()) {
/* Ref = Vcc; in = Vbg (1.1V); Right adjust */
ADMUX = (0 << REFS2) | (0 << REFS1) | (0 << REFS0) |
(0 << ADLAR) |
(1 << MUX3) | (1 << MUX2) | (0 << MUX1) | (0 << MUX0);
/* Enable and start ADC; free running; PS = 64; IRQ enabled */
ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADATE) |
(1 << ADIF) | (1 << ADIE) |
(1 << ADPS2) | (1 << ADPS1) | (0 << ADPS0);
/* Discard the first few results to compensate
* for Vbg settling time (1 ms). */
adc.delay = 10;
} else if (!battery_voltage_is_critical()) {
/* Ref = Vcc; in = ADC2/PB4; Right adjust */
ADMUX = (0 << REFS2) | (0 << REFS1) | (0 << REFS0) |
(0 << ADLAR) |
(0 << MUX3) | (0 << MUX2) | (1 << MUX1) | (0 << MUX0);
/* Enable and start ADC; free running; PS = 64; IRQ enabled */
ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADATE) |
(1 << ADIF) | (1 << ADIE) |
(1 << ADPS2) | (1 << ADPS1) | (0 << ADPS0);
} else {
/* Battery voltage is critical and no battery measurement
* has been requested.
* Keep the ADC shut down. */
}
}
}
/* Returns true, if a battery measurement conversion is currently running. */
bool adc_battery_measurement_running(void)
{
return adc.battery_meas && USE_BAT_MONITOR;
}
/* Request a measurement of the battery voltage.
* Interrupts must be disabled before calling this function. */
void adc_request_battery_measurement(void)
{
if (USE_BAT_MONITOR) {
adc.battery_meas = true;
adc_configure(true);
}
}
/* ADC conversion complete interrupt service routine */
ISR(ADC_vect)
{
uint16_t raw_adc;
uint16_t raw_setpoint;
uint16_t filt_setpoint;
uint16_t vcc_mv;
uint8_t pwm_count;
bool pwm_collision;
memory_barrier();
/* Check if we had a PWM interrupt during our ADC measurement.
* This only checks for collisions with the low frequency IRQ mode PWM.
* Do this check with interrupts still disabled. */
pwm_count = pwm_get_irq_count();
pwm_collision = (pwm_count != adc.prev_pwm_count);
adc.prev_pwm_count = pwm_count;
/* Disable the ADC interrupt and
* globally enable interrupts.
* This allows TIM0_OVF_vect to interrupt us. */
ADCSRA &= (uint8_t)~(1u << ADIE);
irq_enable();
/* Read the analog input */
raw_adc = ADC;
if (adc_battery_measurement_running()) {
/* Battery voltage measurement mode. */
if (adc.delay == 0u) {
/* Convert the raw ADC value to millivolts. */
if (raw_adc > 0u) {
vcc_mv = lim_u16((((uint32_t)ADC_MAX + 1u) * (uint32_t)ADC_VBG_MV) /
(uint32_t)raw_adc);
} else
vcc_mv = UINT16_MAX;
/* Report the measured battery voltage to the
* battery voltage logic. */
evaluate_battery_voltage(vcc_mv);
/* Disable interrupts for
* - PWM shut down
* - ADC re-init */
irq_disable();
if (battery_voltage_is_critical()) {
/* Turn the output off immediately.
* This also reconfigures the
* battery measurement interval. */
output_setpoint(0u);
}
/* We're done.
* Turn off battery measurement mode and
* return to normal ADC operation mode
* (if battery voltage is not critical). */
adc.battery_meas = false;
adc_configure(true);
} else {
/* VRef/Vbg is not stable, yet.
* Continue waiting... */
adc.delay--;
irq_disable();
}
} else if (!pwm_collision) {
/* Normal operation mode.
* Discard this measurement, if an IRQ controlled
* PWM output actuation happened during the measurement. */
if (ADC_INVERT)
raw_adc = ADC_MAX - raw_adc;
/* Transform the value according to the transformation curve. */
raw_setpoint = curve_interpolate(adc2sp_transformation_curve,
ARRAY_SIZE(adc2sp_transformation_curve),
raw_adc);
/* Filter the setpoint value. */
filt_setpoint = lp_filter_run(&adc.filter,
ADC_FILTER_SHIFT,
raw_setpoint);
/* Globally disable interrupts.
* TIM0_OVF_vect must not interrupt re-programming of the PWM below. */
irq_disable();
/* Change the output signal (PWM). */
output_setpoint(filt_setpoint);
if (USE_DEEP_SLEEP) {
/* If the PWM is disabled, request deep sleep to save power. */
system_set_standby(raw_setpoint == 0u);
}
}
/* If deep sleep support is disabled, then the watchdog IRQ is also disabled.
* Poke the watchdog here. */
if (!USE_DEEP_SLEEP)
wdt_reset();
/* Re-enable the ADC interrupt. */
ADCSRA |= (1u << ADIE);
ADCSRA |= (1u << ADIF);
memory_barrier();
}
/* Initialize the input ADC measurement.
* Interrupts must be disabled before calling this function. */
void adc_init(bool enable)
{
lp_filter_reset(&adc.filter);
adc.prev_pwm_count = pwm_get_irq_count();
memory_barrier();
adc_configure(enable);
}
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