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/*
* Copyright 2023 jacqueline <me@jacqueline.id.au>
*
* SPDX-License-Identifier: GPL-3.0-only
*/
#include "adc.hpp"
#include <cstdint>
#include "esp_adc/adc_cali.h"
#include "esp_adc/adc_cali_scheme.h"
#include "esp_adc/adc_oneshot.h"
#include "hal/adc_types.h"
namespace drivers {
static const adc_bitwidth_t kAdcBitWidth = ADC_BITWIDTH_12;
static const adc_unit_t kAdcUnit = ADC_UNIT_1;
// Max battery voltage should be a little over 2V due to our divider, so we need
// the max attenuation to properly handle the full range.
static const adc_atten_t kAdcAttenuation = ADC_ATTEN_DB_11;
// Corresponds to SENSOR_VP.
static const adc_channel_t kAdcChannel = ADC_CHANNEL_0;
AdcBattery::AdcBattery() {
adc_oneshot_unit_init_cfg_t unit_config = {
.unit_id = kAdcUnit,
};
ESP_ERROR_CHECK(adc_oneshot_new_unit(&unit_config, &adc_handle_));
adc_oneshot_chan_cfg_t channel_config = {
.atten = kAdcAttenuation,
.bitwidth = kAdcBitWidth,
};
ESP_ERROR_CHECK(
adc_oneshot_config_channel(adc_handle_, kAdcChannel, &channel_config));
// calibrate
// TODO: compile-time assert our scheme is available
adc_cali_line_fitting_config_t calibration_config = {
.unit_id = kAdcUnit,
.atten = kAdcAttenuation,
.bitwidth = kAdcBitWidth,
};
ESP_ERROR_CHECK(adc_cali_create_scheme_line_fitting(
&calibration_config, &adc_calibration_handle_));
}
AdcBattery::~AdcBattery() {
adc_cali_delete_scheme_line_fitting(adc_calibration_handle_);
ESP_ERROR_CHECK(adc_oneshot_del_unit(adc_handle_));
}
auto AdcBattery::Millivolts() -> uint32_t {
// GPIO 34
int raw = 0;
ESP_ERROR_CHECK(adc_oneshot_read(adc_handle_, kAdcChannel, &raw));
int voltage = 0;
ESP_ERROR_CHECK(
adc_cali_raw_to_voltage(adc_calibration_handle_, raw, &voltage));
// Voltage divider halves the battery voltage to get it into the ADC's range.
return voltage * 2;
}
} // namespace drivers
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