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67 lines
1.9 KiB
67 lines
1.9 KiB
/*
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* Copyright 2023 jacqueline <me@jacqueline.id.au>
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*
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* SPDX-License-Identifier: GPL-3.0-only
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*/
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#include "drivers/adc.hpp"
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#include <cstdint>
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#include "esp_adc/adc_cali.h"
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#include "esp_adc/adc_cali_scheme.h"
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#include "esp_adc/adc_oneshot.h"
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#include "hal/adc_types.h"
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namespace drivers {
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static const adc_bitwidth_t kAdcBitWidth = ADC_BITWIDTH_12;
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static const adc_unit_t kAdcUnit = ADC_UNIT_1;
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// Max battery voltage should be a little over 2V due to our divider, so we need
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// the max attenuation to properly handle the full range.
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static const adc_atten_t kAdcAttenuation = ADC_ATTEN_DB_12;
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// Corresponds to SENSOR_VP.
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static const adc_channel_t kAdcChannel = ADC_CHANNEL_0;
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AdcBattery::AdcBattery() {
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adc_oneshot_unit_init_cfg_t unit_config = {
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.unit_id = kAdcUnit,
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};
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ESP_ERROR_CHECK(adc_oneshot_new_unit(&unit_config, &adc_handle_));
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adc_oneshot_chan_cfg_t channel_config = {
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.atten = kAdcAttenuation,
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.bitwidth = kAdcBitWidth,
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};
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ESP_ERROR_CHECK(
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adc_oneshot_config_channel(adc_handle_, kAdcChannel, &channel_config));
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// calibrate
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// TODO: compile-time assert our scheme is available
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adc_cali_line_fitting_config_t calibration_config = {
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.unit_id = kAdcUnit,
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.atten = kAdcAttenuation,
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.bitwidth = kAdcBitWidth,
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};
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ESP_ERROR_CHECK(adc_cali_create_scheme_line_fitting(
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&calibration_config, &adc_calibration_handle_));
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}
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AdcBattery::~AdcBattery() {
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adc_cali_delete_scheme_line_fitting(adc_calibration_handle_);
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ESP_ERROR_CHECK(adc_oneshot_del_unit(adc_handle_));
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}
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auto AdcBattery::Millivolts() -> uint32_t {
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// GPIO 34
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int raw = 0;
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ESP_ERROR_CHECK(adc_oneshot_read(adc_handle_, kAdcChannel, &raw));
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int voltage = 0;
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ESP_ERROR_CHECK(
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adc_cali_raw_to_voltage(adc_calibration_handle_, raw, &voltage));
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// Voltage divider halves the battery voltage to get it into the ADC's range.
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return voltage * 2;
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}
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} // namespace drivers
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