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50 lines
2.2 KiB
C
50 lines
2.2 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 "../curve_fitting_coefficients.h"
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#define COEFF_GROUP_NUM 4
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#define TERM_MAX 5
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/**
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* @note Error Calculation
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* Coefficients for calculating the reading voltage error.
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* Four sets of coefficients for atten0 ~ atten3 respectively.
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*
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* For each item, first element is the Coefficient, second element is the Multiple. (Coefficient / Multiple) is the real coefficient.
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*
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* @note {0,0} stands for unused item
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* @note In case of the overflow, these coefficients are recorded as Absolute Value
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* @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);
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* @note Above formula is rewritten from the original documentation, please note that the coefficients are re-ordered.
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* @note ADC1 and ADC2 use same coefficients
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*/
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const static uint64_t adc1_error_coef_atten[COEFF_GROUP_NUM][TERM_MAX][2] = {
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{{225966470500043, 1e15}, {7265418501948, 1e16}, {109410402681, 1e16}, {0, 0}, {0, 0}}, //atten0
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{{4229623392600516, 1e16}, {731527490903, 1e16}, {88166562521, 1e16}, {0, 0}, {0, 0}}, //atten1
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{{1017859239236435, 1e15}, {97159265299153, 1e16}, {149794028038, 1e16}, {0, 0}, {0, 0}}, //atten2
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{{14912262772850453, 1e16}, {228549975564099, 1e16}, {356391935717, 1e16}, {179964582, 1e16}, {42046, 1e16}} //atten3
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};
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/**
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* Term sign
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*/
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const static int32_t adc1_error_sign[COEFF_GROUP_NUM][TERM_MAX] = {
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{-1, -1, 1, 0, 0}, //atten0
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{ 1, -1, 1, 0, 0}, //atten1
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{-1, -1, 1, 0, 0}, //atten2
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{-1, -1, 1, -1, 1} //atten3
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};
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void curve_fitting_get_second_step_coeff(const adc_cali_curve_fitting_config_t *config, cali_chars_second_step_t *ctx)
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{
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ctx->term_num = (config->atten == 3) ? 5 : 3;
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// On esp32c3, ADC1 and ADC2 share the second step coefficients
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// And if the target only has 1 ADC peripheral, just use the ADC1 directly
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ctx->coeff = adc1_error_coef_atten[config->atten];
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ctx->sign = adc1_error_sign[config->atten];
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}
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