/* * SPDX-FileCopyrightText: 2019-2021 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 "driver/adc.h" #include "hal/adc_ll.h" #include "esp32c3/esp_efuse_rtc_calib.h" #include "esp_adc_cal.h" #include "../esp_adc_cal_internal.h" #define ADC_CALIB_CHECK(cond, err_msg, ret) do {\ if (!(cond)) { \ ESP_LOGE(LOG_TAG, err_msg); \ return (ret); \ } \ } while(0) const static char LOG_TAG[] = "adc_calib"; /* ------------------------ 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 = 65536; /** * @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 = (K0 * X^0) + (K1 * X^1) + (K2 * X^2); For atten3, error = (K0 * X^0) + (K1 * X^1) + (K2 * X^2) + (K3 * X^3) + (K4 * X^4); * @note Above formula is rewritten from the original documentation, please note that the coefficients are re-ordered. * @note ADC1 and ADC2 use same coeffients */ const static uint64_t adc_error_coef_atten[4][5][2] = { {{225966470500043, 1e15}, {7265418501948, 1e16}, {109410402681, 1e16}, {0, 0}, {0, 0}}, //atten0 {{4229623392600516, 1e16}, {731527490903, 1e16}, {88166562521, 1e16}, {0, 0}, {0, 0}}, //atten1 {{1017859239236435, 1e15}, {97159265299153, 1e16}, {149794028038, 1e16}, {0, 0}, {0, 0}}, //atten2 {{14912262772850453, 1e16}, {228549975564099, 1e16}, {356391935717, 1e16}, {179964582, 1e16}, {42046, 1e16}} //atten3 }; /** * Term sign * @note ADC1 and ADC2 use same coeffients */ const static int32_t adc_error_sign[4][5] = { {-1, -1, 1, 0, 0}, //atten0 { 1, -1, 1, 0, 0}, //atten1 {-1, -1, 1, 0, 0}, //atten2 {-1, -1, 1, -1, 1} //atten3 }; /* -------------------- Characterization Helper Data Types ------------------ */ typedef struct { uint32_t voltage; uint32_t digi; } adc_calib_data_ver1; typedef struct { char version_num; adc_unit_t adc_num; adc_atten_t atten_level; union { adc_calib_data_ver1 ver1; } efuse_data; } adc_calib_parsed_info_t; static esp_err_t prepare_calib_data_for(int version_num, adc_unit_t adc_num, adc_atten_t atten, adc_calib_parsed_info_t *parsed_data_storage) { assert(version_num == 1); esp_err_t ret; parsed_data_storage->version_num = version_num; parsed_data_storage->adc_num = adc_num; parsed_data_storage->atten_level = atten; // V1 we don't have calibration data for ADC2, using the efuse data of ADC1 uint32_t voltage, digi; ret = esp_efuse_rtc_calib_get_cal_voltage(version_num, atten, &digi, &voltage); if (ret != ESP_OK) { return ret; } parsed_data_storage->efuse_data.ver1.voltage = voltage; parsed_data_storage->efuse_data.ver1.digi = digi; return ret; } /* ----------------------- Characterization Functions ----------------------- */ /* * Estimate the (assumed) linear relationship btwn the measured raw value and the voltage * with the previously done measurement when the chip was manufactured. */ static void calculate_characterization_coefficients(const adc_calib_parsed_info_t *parsed_data, esp_adc_cal_characteristics_t *chars) { ESP_LOGD(LOG_TAG, "Calib V1, Cal Voltage = %d, Digi out = %d\n", parsed_data->efuse_data.ver1.voltage, parsed_data->efuse_data.ver1.digi); chars->coeff_a = coeff_a_scaling * parsed_data->efuse_data.ver1.voltage / parsed_data->efuse_data.ver1.digi; chars->coeff_b = 0; } /* ------------------------- Public API ------------------------------------- */ esp_err_t esp_adc_cal_check_efuse(esp_adc_cal_value_t source) { if (source != ESP_ADC_CAL_VAL_EFUSE_TP) { 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; } 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) { esp_err_t ret; adc_calib_parsed_info_t efuse_parsed_data = {0}; // Check parameters ADC_CALIB_CHECK(adc_num == ADC_UNIT_1 || adc_num == ADC_UNIT_2, "Invalid unit num", ESP_ADC_CAL_VAL_NOT_SUPPORTED); ADC_CALIB_CHECK(chars != NULL, "Invalid characteristic", ESP_ADC_CAL_VAL_NOT_SUPPORTED); ADC_CALIB_CHECK(bit_width == ADC_WIDTH_BIT_12, "Invalid bit_width", ESP_ADC_CAL_VAL_NOT_SUPPORTED); ADC_CALIB_CHECK(atten < 4, "Invalid attenuation", ESP_ADC_CAL_VAL_NOT_SUPPORTED); int version_num = esp_efuse_rtc_calib_get_ver(); ADC_CALIB_CHECK(version_num == 1, "No calibration efuse burnt", ESP_ADC_CAL_VAL_NOT_SUPPORTED); memset(chars, 0, sizeof(esp_adc_cal_characteristics_t)); // make sure adc is calibrated. ret = prepare_calib_data_for(version_num, adc_num, atten, &efuse_parsed_data); if (ret != ESP_OK) { abort(); } calculate_characterization_coefficients(&efuse_parsed_data, chars); ESP_LOGD(LOG_TAG, "adc%d (atten leven %d) calibration done: A:%d B:%d\n", adc_num, atten, chars->coeff_a, chars->coeff_b); // Initialize remaining fields chars->adc_num = adc_num; chars->atten = atten; chars->bit_width = bit_width; // in esp32c3 we only use the two point method to calibrate the adc. return ESP_ADC_CAL_VAL_EFUSE_TP; } uint32_t esp_adc_cal_raw_to_voltage(uint32_t adc_reading, const esp_adc_cal_characteristics_t *chars) { assert(chars != NULL); int32_t error = 0; uint64_t v_cali_1 = adc_reading * chars->coeff_a / coeff_a_scaling; esp_adc_error_calc_param_t param = { .v_cali_input = v_cali_1, .term_num = (chars->atten == 3) ? 5 : 3, .coeff = &adc_error_coef_atten, .sign = &adc_error_sign, }; error = esp_adc_cal_get_reading_error(¶m, chars->atten); return (int32_t)v_cali_1 - error; }