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https://github.com/espressif/esp-idf.git
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202 lines
8.1 KiB
C
202 lines
8.1 KiB
C
/*
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* SPDX-FileCopyrightText: 2019-2023 Espressif Systems (Shanghai) CO LTD
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <stdint.h>
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#include "esp_types.h"
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#include "soc/efuse_periph.h"
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#include "esp_err.h"
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#include "esp_check.h"
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#include "assert.h"
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#include "esp_efuse.h"
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#include "esp_efuse_table.h"
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#include "esp_efuse_rtc_table.h"
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#include "hal/adc_hal.h"
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#include "hal/adc_types.h"
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#include "driver/adc_types_legacy.h"
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#include "esp_adc_cal_types_legacy.h"
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const static char LOG_TAG[] = "adc_calib";
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/* ------------------------ Characterization Constants ---------------------- */
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// coeff_a and coeff_b are actually floats
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// they are scaled to put them into uint32_t so that the headers do not have to be changed
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static const int coeff_a_scaling = 65536;
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static const int coeff_b_scaling = 1024;
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/* -------------------- Characterization Helper Data Types ------------------ */
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typedef struct {
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int adc_calib_high;
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int adc_calib_low;
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} adc_calib_data_ver1;
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typedef struct {
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int adc_calib_high; // the reading of adc ...
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int adc_calib_high_voltage; // ... at this voltage (mV)
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} adc_calib_data_ver2;
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typedef struct {
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char version_num;
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adc_unit_t adc_num;
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adc_atten_t atten_level;
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union {
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adc_calib_data_ver1 ver1;
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adc_calib_data_ver2 ver2;
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} efuse_data;
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} adc_calib_parsed_info;
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static bool prepare_calib_data_for(adc_unit_t adc_num, adc_atten_t atten, adc_calib_parsed_info *parsed_data_storage)
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{
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int version_num = esp_efuse_rtc_table_read_calib_version();
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int tag;
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parsed_data_storage->version_num = version_num;
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parsed_data_storage->adc_num = adc_num;
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parsed_data_storage->atten_level = atten;
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switch (version_num) {
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case 1:
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// note: use the adc_num as in hal, which start from 0.
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tag = esp_efuse_rtc_table_get_tag(version_num, adc_num, atten, RTCCALIB_V1_PARAM_VLOW);
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parsed_data_storage->efuse_data.ver1.adc_calib_low = esp_efuse_rtc_table_get_parsed_efuse_value(tag, false);
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tag = esp_efuse_rtc_table_get_tag(version_num, adc_num, atten, RTCCALIB_V1_PARAM_VHIGH);
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parsed_data_storage->efuse_data.ver1.adc_calib_high = esp_efuse_rtc_table_get_parsed_efuse_value(tag, false);
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break;
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case 2:
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tag = esp_efuse_rtc_table_get_tag(version_num, adc_num, atten, RTCCALIB_V2_PARAM_VHIGH);
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parsed_data_storage->efuse_data.ver2.adc_calib_high = esp_efuse_rtc_table_get_parsed_efuse_value(tag, false);
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switch (parsed_data_storage->atten_level) {
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case ADC_ATTEN_DB_0:
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parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 600;
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break;
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case ADC_ATTEN_DB_2_5:
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parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 800;
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break;
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case ADC_ATTEN_DB_6:
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parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 1000;
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break;
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case ADC_ATTEN_DB_11:
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parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 2000;
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break;
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default:
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break;
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}
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break;
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default:
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// fall back to case 1 with zeros as params.
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parsed_data_storage->version_num = 1;
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tag = esp_efuse_rtc_table_get_tag(version_num, adc_num, atten, RTCCALIB_V1_PARAM_VLOW);
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parsed_data_storage->efuse_data.ver1.adc_calib_high = esp_efuse_rtc_table_get_parsed_efuse_value(tag, true);
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tag = esp_efuse_rtc_table_get_tag(version_num, adc_num, atten, RTCCALIB_V1_PARAM_VHIGH);
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parsed_data_storage->efuse_data.ver1.adc_calib_low = esp_efuse_rtc_table_get_parsed_efuse_value(tag, true);
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break;
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}
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return true;
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}
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/* ----------------------- Characterization Functions ----------------------- */
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/**
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* (Used in V1 of calibration scheme)
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* The Two Point calibration measures the reading at two specific input voltages, and calculates the (assumed linear) relation
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* between input voltage and ADC response. (Response = A * Vinput + B)
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* A and B are scaled ints.
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* @param high The ADC response at the higher voltage of the corresponding attenuation (600mV, 800mV, 1000mV, 2000mV).
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* @param low The ADC response at the lower voltage of the corresponding attenuation (all 250mV).
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*
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*/
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static void characterize_using_two_point(adc_unit_t adc_num,
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adc_atten_t atten,
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uint32_t high,
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uint32_t low,
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uint32_t *coeff_a,
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uint32_t *coeff_b)
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{
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// once we have recovered the reference high(Dhigh) and low(Dlow) readings, we can calculate a and b from
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// the measured high and low readings
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static const uint32_t v_high[] = {600, 800, 1000, 2000};
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static const uint32_t v_low = 250;
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*coeff_a = coeff_a_scaling * (v_high[atten] - v_low) / (high - low);
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*coeff_b = coeff_b_scaling * (v_low * high - v_high[atten] * low) / (high - low);
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}
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/*
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* Estimate the (assumed) linear relationship btwn the measured raw value and the voltage
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* with the previously done measurement when the chip was manufactured.
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* */
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static bool calculate_characterization_coefficients(const adc_calib_parsed_info *parsed_data, esp_adc_cal_characteristics_t *chars)
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{
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switch (parsed_data->version_num) {
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case 1:
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ESP_LOGD(LOG_TAG, "Calib V1, low%dmV, high%dmV", parsed_data->efuse_data.ver1.adc_calib_low, parsed_data->efuse_data.ver1.adc_calib_high);
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characterize_using_two_point(parsed_data->adc_num, parsed_data->atten_level,
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parsed_data->efuse_data.ver1.adc_calib_high, parsed_data->efuse_data.ver1.adc_calib_low,
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&(chars->coeff_a), &(chars->coeff_b));
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break;
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case 2:
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ESP_LOGD(LOG_TAG, "Calib V2, volt%dmV", parsed_data->efuse_data.ver2.adc_calib_high);
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chars->coeff_a = coeff_a_scaling * parsed_data->efuse_data.ver2.adc_calib_high_voltage /
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parsed_data->efuse_data.ver2.adc_calib_high;
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chars->coeff_b = 0;
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break;
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default:
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return false;
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break;
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}
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return true;
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}
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/* ------------------------- Public API ------------------------------------- */
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esp_err_t esp_adc_cal_check_efuse(esp_adc_cal_value_t source)
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{
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if (source != ESP_ADC_CAL_VAL_EFUSE_TP) {
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return ESP_ERR_NOT_SUPPORTED;
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}
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uint8_t adc_encoding_version = esp_efuse_rtc_table_read_calib_version();
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if (adc_encoding_version != 1 && adc_encoding_version != 2) {
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// current version only accepts encoding ver 1 and ver 2.
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return ESP_ERR_INVALID_VERSION;
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}
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return ESP_OK;
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}
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esp_adc_cal_value_t esp_adc_cal_characterize(adc_unit_t adc_num,
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adc_atten_t atten,
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adc_bits_width_t bit_width,
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uint32_t default_vref,
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esp_adc_cal_characteristics_t *chars)
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{
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bool res __attribute__((unused));
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adc_calib_parsed_info efuse_parsed_data = {0};
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// Check parameters
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assert((adc_num == ADC_UNIT_1) || (adc_num == ADC_UNIT_2));
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assert(chars != NULL);
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assert(bit_width == ADC_WIDTH_BIT_13);
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// make sure adc is calibrated.
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res = prepare_calib_data_for(adc_num, atten, &efuse_parsed_data);
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assert(res);
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res = calculate_characterization_coefficients(&efuse_parsed_data, chars);
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assert(res);
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ESP_LOGD(LOG_TAG, "adc%d (atten leven %d) calibration done: A:%" PRId32 " B:%" PRId32, adc_num, atten, chars->coeff_a, chars->coeff_b);
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// Initialize remaining fields
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chars->adc_num = adc_num;
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chars->atten = atten;
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chars->bit_width = bit_width;
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// these values are not used as the corresponding calibration themes are deprecated.
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chars->vref = 0;
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chars->low_curve = NULL;
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chars->high_curve = NULL;
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// in esp32s2 we only use the two point method to calibrate the adc.
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return ESP_ADC_CAL_VAL_EFUSE_TP;
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}
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uint32_t esp_adc_cal_raw_to_voltage(uint32_t adc_reading, const esp_adc_cal_characteristics_t *chars)
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{
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assert(chars != NULL);
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return adc_reading * chars->coeff_a / coeff_a_scaling + chars->coeff_b / coeff_b_scaling;
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}
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