esp-idf/components/esp_adc_cal/esp32c3/esp_adc_cal.c

173 lines
6.9 KiB
C

/*
* SPDX-FileCopyrightText: 2019-2021 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include "esp_types.h"
#include "esp_err.h"
#include "esp_log.h"
#include "esp_check.h"
#include "driver/adc.h"
#include "hal/adc_ll.h"
#include "esp_efuse_rtc_calib.h"
#include "esp_adc_cal.h"
#include "../esp_adc_cal_internal.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 = 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
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(bit_width == ADC_WIDTH_BIT_12, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "Invalid bit_width");
ESP_RETURN_ON_FALSE(atten < 4, 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));
// 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(&param, chars->atten);
return (int32_t)v_cali_1 - error;
}