/* * SPDX-FileCopyrightText: 2020-2021 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Apache-2.0 */ #include #include #include #include "esp_types.h" #include "esp_err.h" #include "esp_log.h" #include "esp_check.h" #include "driver/adc.h" #include "hal/adc_types.h" #include "esp_efuse_rtc_calib.h" #include "esp_adc_cal.h" const static char LOG_TAG[] = "ADC_CALI"; /* ------------------------ Characterization Constants ---------------------- */ //coeff_a is actually a float number //it is scaled to put them into uint32_t so that the headers do not have to be changed static const int coeff_a_scaling = 1000000; /** * @note Error Calculation * Coefficients for calculating the reading voltage error. * Four sets of coefficients for atten0 ~ atten3 respectively. * * For each item, first element is the Coefficient, second element is the Multiple. (Coefficient / Multiple) is the real coefficient. * * @note {0,0} stands for unused item * @note In case of the overflow, these coeffcients are recorded as Absolute Value * @note For atten0 ~ 2, error = a1 * X^2 + a2 * X + a3; For atten3, error = a1 * X^4 + a2 * X^3 + a3 * X^2 + a4 * X + a5; */ const static uint64_t adc_error_coef_atten[4][10][2] = { {{9798249589, 1e15}, {50871540569528, 1e16}, {3, 1}, {0, 0}, {0, 0}, //ADC1 atten0 {36615265189, 1e16}, {1353548869615, 1e16}, {3, 1}, {0, 0}, {0, 0}}, //ADC2 atten0 {{101379430548, 1e16}, {49393185868806, 1e16}, {3, 1}, {0, 0}, {0, 0}, //ADC1 atten1 {118964995959, 1e16}, {66319894226185, 1e16}, {2, 1}, {0, 0}, {0, 0}}, //ADC2 atten1 {{208385525314, 1e16}, {147640181047414, 1e16}, {2, 1}, {0, 0}, {0, 0}, //ADC1 atten2 {259011467956, 1e16}, {200996773954387, 1e16}, {1, 1}, {0, 0}, {0, 0}}, //ADC2 atten2 {{13515, 1e15}, {70769718, 1e15}, {1297891447611, 1e16}, {644334888647536, 1e16}, {1,1}, //ADC1 atten3 {15038, 1e15}, {79672528, 1e15}, {1478791187119, 1e16}, {755717904943462, 1e16}, {1,1}} //ADC2 atten3 }; const static int32_t adc_error_sign[4][10] = { {1, -1, -1, 0, 0, //ADC1 atten0 1, 1, -1, 0, 0}, //ADC2 atten0 {1, -1, -1, 0, 0, //ADC1 atten1 1, -1, -1, 0, 0}, //ADC2 atten1 {1, -1, -1, 0, 0, //ADC1 atten2 1, -1, -1, 0, 0}, //ADC2 atten2 {1, -1, 1, -1, -1, //ADC1 atten3 1, -1, 1, -1, 1} //ADC2 atten3 }; /* -------------------- Characterization Helper Data Types ------------------ */ typedef struct { uint32_t voltage; uint32_t digi; } adc_calib_data_ver1_t; typedef struct { char version_num; adc_unit_t adc_num; adc_atten_t atten_level; union { adc_calib_data_ver1_t ver1; } ref_data; } adc_calib_info_t; //To get the reference point (Dout, Vin) static esp_err_t get_reference_point(int version_num, adc_unit_t adc_num, adc_atten_t atten, adc_calib_info_t *calib_info) { assert(version_num == 1); esp_err_t ret; calib_info->version_num = version_num; calib_info->adc_num = adc_num; calib_info->atten_level = atten; uint32_t voltage = 0; uint32_t digi = 0; ret = esp_efuse_rtc_calib_get_cal_voltage(version_num, ((adc_num == ADC_UNIT_1) ? 0 : 1), atten, &digi, &voltage); assert(ret == ESP_OK); calib_info->ref_data.ver1.voltage = voltage; calib_info->ref_data.ver1.digi = digi; return ret; } esp_err_t esp_adc_cal_check_efuse(esp_adc_cal_value_t source) { if (source != ESP_ADC_CAL_VAL_EFUSE_TP_FIT) { return ESP_ERR_NOT_SUPPORTED; } uint8_t adc_encoding_version = esp_efuse_rtc_calib_get_ver(); if (adc_encoding_version != 1) { // current version only accepts encoding ver 1. return ESP_ERR_INVALID_VERSION; } return ESP_OK; } /* * Get an expected linear relationship btwn Vin and Dout */ static void calculate_characterization_coefficients(const adc_calib_info_t *parsed_data, esp_adc_cal_characteristics_t *chars) { chars->coeff_a = coeff_a_scaling * parsed_data->ref_data.ver1.voltage / parsed_data->ref_data.ver1.digi; chars->coeff_b = 0; ESP_LOGV(LOG_TAG, "Calib V1, Cal Voltage = %d, Digi out = %d, Coef_a = %d\n", parsed_data->ref_data.ver1.voltage, parsed_data->ref_data.ver1.digi, chars->coeff_a); } esp_adc_cal_value_t esp_adc_cal_characterize(adc_unit_t adc_num, adc_atten_t atten, adc_bits_width_t bit_width, uint32_t default_vref, esp_adc_cal_characteristics_t *chars) { (void) default_vref; // Check parameters ESP_RETURN_ON_FALSE(adc_num == ADC_UNIT_1 || adc_num == ADC_UNIT_2, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "Invalid unit num"); ESP_RETURN_ON_FALSE(chars != NULL, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "Ivalid characteristic"); ESP_RETURN_ON_FALSE(atten < ADC_ATTEN_MAX, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "Invalid attenuation"); int version_num = esp_efuse_rtc_calib_get_ver(); ESP_RETURN_ON_FALSE(version_num == 1, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "No calibration efuse burnt"); memset(chars, 0, sizeof(esp_adc_cal_characteristics_t)); adc_calib_info_t calib_info = {0}; // make sure adc is calibrated. get_reference_point(version_num, adc_num, atten, &calib_info); calculate_characterization_coefficients(&calib_info, chars); // Initialize remaining fields chars->adc_num = adc_num; chars->atten = atten; chars->bit_width = bit_width; return ESP_ADC_CAL_VAL_EFUSE_TP_FIT; } static int32_t get_reading_error(uint64_t v_cali_1, uint8_t adc_num, uint8_t atten) { if (v_cali_1 == 0) { return 0; } uint8_t term_max = (atten == 3) ? 5 : 3; int32_t error = 0; uint64_t coeff = 0; uint64_t term[5] = {0}; /** * For atten0 ~ 2: * error = a1 * X^2 + a2 * X + a3; * * For atten3: * error = a1 * X^4 + a2 * X^3 + a3 * X^2 + a4 * X + a5; */ //Calculate all the power beforehand term[term_max-1] = 1; term[term_max-2] = v_cali_1; for (int term_id = term_max - 3; term_id >= 0; term_id--) { term[term_id] = term[term_id + 1] * v_cali_1; } //Calculate each term uint8_t coef_id_start = (adc_num == ADC_UNIT_1) ? 0 : 5; for (int i = 0; i < term_max; i++) { coeff = adc_error_coef_atten[atten][coef_id_start + i][0]; term[i] = term[i] * coeff; ESP_LOGV(LOG_TAG, "big coef is %llu, big term%d is %llu, coef_id is %d", coeff, i, term[i], coef_id_start + i); term[i] = term[i] / adc_error_coef_atten[atten][coef_id_start + i][1]; error += (int32_t)term[i] * adc_error_sign[atten][i]; ESP_LOGV(LOG_TAG, "term%d is %llu, error is %d", i, term[i], error); } return error; } uint32_t esp_adc_cal_raw_to_voltage(uint32_t adc_reading, const esp_adc_cal_characteristics_t *chars) { assert(chars != NULL); //ADC reading won't exceed 4096. Otherwise the raw reading result is wrong, the next calculation will overflow. assert(adc_reading < 4096); uint32_t voltage = 0; int32_t error = 0; uint64_t v_cali_1 = 0; //raw * gradient * 1000000 v_cali_1 = adc_reading * chars->coeff_a; //convert to real number v_cali_1 = v_cali_1 / coeff_a_scaling; ESP_LOGV(LOG_TAG, "v_cali_1 is %llu", v_cali_1); error = get_reading_error(v_cali_1, chars->adc_num, chars->atten); voltage = (int32_t)v_cali_1 - error; return voltage; } esp_err_t esp_adc_cal_get_voltage(adc_channel_t channel, const esp_adc_cal_characteristics_t *chars, uint32_t *voltage) { // Check parameters ESP_RETURN_ON_FALSE(chars != NULL, ESP_ERR_INVALID_ARG, LOG_TAG, "No characteristic input"); ESP_RETURN_ON_FALSE(voltage != NULL, ESP_ERR_INVALID_ARG, LOG_TAG, "No output buffer"); esp_err_t ret = ESP_OK; int adc_reading; if (chars->adc_num == ADC_UNIT_1) { ESP_RETURN_ON_FALSE(channel < SOC_ADC_CHANNEL_NUM(0), ESP_ERR_INVALID_ARG, LOG_TAG, "Invalid channel"); adc_reading = adc1_get_raw(channel); } else { ESP_RETURN_ON_FALSE(channel < SOC_ADC_CHANNEL_NUM(1), ESP_ERR_INVALID_ARG, LOG_TAG, "Invalid channel"); ret = adc2_get_raw(channel, chars->bit_width, &adc_reading); } *voltage = esp_adc_cal_raw_to_voltage((uint32_t)adc_reading, chars); return ret; }