esp-idf/components/esp_adc/esp32c6/curve_fitting_coefficients.c

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/*
* SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdio.h>
#include <stdint.h>
#include "esp_efuse_rtc_calib.h"
#include "../curve_fitting_coefficients.h"
#define COEFF_VERSION_NUM 2 // Currently C6 has two versions of curve calibration schemes
#define COEFF_GROUP_NUM 4
#define TERM_MAX 3
/**
* @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 coefficients are recorded as Absolute Value
* @note For atten0 ~ 3, error = (K0 * X^0) + (K1 * X^1) + (K2 * X^2)
* @note Above formula is rewritten from the original documentation, please note that the coefficients are re-ordered.
*/
const static uint64_t adc1_error_coef_atten[COEFF_VERSION_NUM][COEFF_GROUP_NUM][TERM_MAX][2] = {
/* Coefficients of calibration version 1 */
{
{{487166399931449, 1e15}, {6436483033201, 1e16}, {30410131806, 1e16}}, //atten0
{{8665498165817785, 1e16}, {15239070452946, 1e16}, {13818878844, 1e16}}, //atten1
{{12277821756674387, 1e16}, {22275554717885, 1e16}, {5924302667, 1e16}}, //atten2
{{3801417550380255, 1e16}, {6020352420772, 1e16}, {12442478488, 1e16}}, //atten3
},
/* Coefficients of calibration version 2 */
{
{{0, 0}, {0, 0}, {0, 0}}, //atten0
{{0, 0}, {0, 0}, {0, 0}}, //atten1
{{12217864764388775, 1e16}, {1954123107752, 1e16}, {6409679727, 1e16}}, //atten2
{{3915910437042445, 1e16}, {31536470857564, 1e16}, {12493873014, 1e16}}, //atten3
},
};
/**
* Term sign
*/
const static int32_t adc1_error_sign[COEFF_VERSION_NUM][COEFF_GROUP_NUM][TERM_MAX] = {
/* Coefficient sign of calibration version 1 */
{
{-1, 1, 1}, //atten0
{-1, 1, 1}, //atten1
{-1, 1, 1}, //atten2
{-1, -1, 1}, //atten3
},
/* Coefficient sign of calibration version 2 */
{
{ 0, 0, 0}, //atten0
{ 0, 0, 0}, //atten1
{-1, -1, 1}, //atten2
{-1, -1, 1}, //atten3
},
};
void curve_fitting_get_second_step_coeff(const adc_cali_curve_fitting_config_t *config, cali_chars_second_step_t *ctx)
{
uint32_t adc_calib_ver = esp_efuse_rtc_calib_get_ver();
assert((adc_calib_ver >= ESP_EFUSE_ADC_CALIB_VER_MIN) &&
(adc_calib_ver <= ESP_EFUSE_ADC_CALIB_VER_MAX));
if (adc_calib_ver == ESP_EFUSE_ADC_CALIB_VER2 && config->atten < 2) {
ctx->term_num = 0;
ctx->coeff = NULL;
ctx->sign = NULL;
} else {
ctx->term_num = 3;
ctx->coeff = adc1_error_coef_atten[VER2IDX(adc_calib_ver)][config->atten];
ctx->sign = adc1_error_sign[VER2IDX(adc_calib_ver)][config->atten];
}
}