esp-idf/components/esp_adc/esp32c3/curve_fitting_coefficients.c

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/*
* SPDX-FileCopyrightText: 2019-2023 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdint.h>
#include "../curve_fitting_coefficients.h"
/**
* @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 ~ 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 coefficients
*/
const static uint64_t adc1_error_coef_atten[COEFF_GROUP_NUM][TERM_MAX][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
*/
const static int32_t adc1_error_sign[COEFF_GROUP_NUM][TERM_MAX] = {
{-1, -1, 1, 0, 0}, //atten0
{ 1, -1, 1, 0, 0}, //atten1
{-1, -1, 1, 0, 0}, //atten2
{-1, -1, 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)
{
ctx->term_num = (config->atten == 3) ? 5 : 3;
// On esp32c3, ADC1 and ADC2 share the second step coefficients
// And if the target only has 1 ADC peripheral, just use the ADC1 directly
ctx->coeff = &adc1_error_coef_atten;
ctx->sign = &adc1_error_sign;
}