esp-idf/components/esp_adc/esp32c2/adc_cali_line_fitting.c

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/*
* SPDX-FileCopyrightText: 2022-2023 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 "esp_heap_caps.h"
#include "esp_efuse_rtc_calib.h"
#include "soc/soc_caps.h"
#include "esp_adc/adc_cali_scheme.h"
#include "adc_cali_interface.h"
/**
* This file contains Line Fitting Calibration Scheme for ESP32C2.
*
* If ESP EFuse Line Fitting Calibration Scheme on future chips are similar to the scheme in this file, we can:
*
* 1. Rename this file to `adc_cali_line_fitting_v2.c`, as the Line Fitting Scheme on ESP32 and ESP32S2 are different to this.
* 2. Move this file to common directory
* 3. Still support `ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED`
* 4. Add a new internal maccro `ADC_CALI_SCHEME_LINE_FITTING_V2_SUPPORTED`
* 5. Only build this file, when `ADC_CALI_SCHEME_LINE_FITTING_V2_SUPPORTED == true`
*/
// 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;
const static char *TAG = "adc_cali";
typedef struct {
adc_unit_t unit_id;
adc_atten_t atten;
uint32_t coeff_a; ///< Gradient of ADC-Voltage characteristics
uint32_t coeff_b; ///< Offset of ADC-Voltage characteristics
} cali_chars_line_fitting_t;
/* ------------------------ Interface Functions --------------------------- */
static esp_err_t cali_raw_to_voltage(void *arg, int raw, int *voltage);
static esp_err_t check_valid(const adc_cali_line_fitting_config_t *config);
/* ------------------------- Public API ------------------------------------- */
esp_err_t adc_cali_create_scheme_line_fitting(const adc_cali_line_fitting_config_t *config, adc_cali_handle_t *ret_handle)
{
esp_err_t ret = ESP_OK;
ESP_RETURN_ON_FALSE(config && ret_handle, ESP_ERR_INVALID_ARG, TAG, "invalid arg: null pointer");
ret = check_valid(config);
if (ret != ESP_OK) {
return ret;
}
//current version only accepts encoding version: ESP_EFUSE_ADC_CALIB_VER_MIN <= adc_encoding_version <= ESP_EFUSE_ADC_CALIB_VER_MAX.
uint8_t adc_cali_version = esp_efuse_rtc_calib_get_ver();
ESP_RETURN_ON_FALSE((adc_cali_version >= ESP_EFUSE_ADC_CALIB_VER_MIN) &&
(adc_cali_version <= ESP_EFUSE_ADC_CALIB_VER_MAX), ESP_ERR_NOT_SUPPORTED, TAG, "Calibration required eFuse bits not burnt");
adc_cali_scheme_t *scheme = (adc_cali_scheme_t *)heap_caps_calloc(1, sizeof(adc_cali_scheme_t), MALLOC_CAP_INTERNAL | MALLOC_CAP_8BIT);
ESP_RETURN_ON_FALSE(scheme, ESP_ERR_NO_MEM, TAG, "no mem for adc calibration scheme");
cali_chars_line_fitting_t *chars = (cali_chars_line_fitting_t *)heap_caps_calloc(1, sizeof(cali_chars_line_fitting_t), MALLOC_CAP_INTERNAL | MALLOC_CAP_8BIT);
ESP_GOTO_ON_FALSE(chars, ESP_ERR_NO_MEM, err, TAG, "no memory for the calibration characteristics");
scheme->raw_to_voltage = cali_raw_to_voltage;
scheme->ctx = chars;
chars->unit_id = config->unit_id;
chars->atten = config->atten;
uint32_t voltage_mv = 0;
uint32_t digi_val = 0;
ret = esp_efuse_rtc_calib_get_cal_voltage(adc_cali_version, chars->unit_id, chars->atten, &digi_val, &voltage_mv);
assert(ret == ESP_OK);
chars->coeff_a = coeff_a_scaling * voltage_mv / digi_val;
chars->coeff_b = 0;
ESP_LOGV(TAG, "Calib V1, Cal Voltage = %"PRId32", Digi out = %"PRId32", Coef_a = %"PRId32"\n", voltage_mv, digi_val, chars->coeff_a);
*ret_handle = scheme;
return ESP_OK;
err:
if (scheme) {
free(scheme);
}
return ret;
}
esp_err_t adc_cali_delete_scheme_line_fitting(adc_cali_handle_t handle)
{
ESP_RETURN_ON_FALSE(handle, ESP_ERR_INVALID_ARG, TAG, "invalid argument: null pointer");
free(handle->ctx);
handle->ctx = NULL;
free(handle);
handle = NULL;
return ESP_OK;
}
/* ------------------------ Interface Functions --------------------------- */
static esp_err_t cali_raw_to_voltage(void *arg, int raw, int *voltage)
{
//pointers are checked in the upper layer
cali_chars_line_fitting_t *ctx = arg;
*voltage = raw * ctx->coeff_a / coeff_a_scaling + ctx->coeff_b;
return ESP_OK;
}
static esp_err_t check_valid(const adc_cali_line_fitting_config_t *config)
{
ESP_RETURN_ON_FALSE(config->unit_id < SOC_ADC_PERIPH_NUM, ESP_ERR_INVALID_ARG, TAG, "invalid ADC unit");
ESP_RETURN_ON_FALSE((config->atten == ADC_ATTEN_DB_0 || config->atten == ADC_ATTEN_DB_11), ESP_ERR_NOT_SUPPORTED, TAG, "only ADC_ATTEN_DB_0 and ADC_ATTEN_DB_11 are supported");
if (config->atten == ADC_ATTEN_DB_0) {
ESP_LOGW(TAG, "Experimental: ADC Atten 0 calibration can now only used for inputs lower than 950mV. Calibration Scheme may get updated, DON'T USE FOR MASS PRODUCTION!");
}
bool available_oneshot_bitwidth = (config->bitwidth >= SOC_ADC_RTC_MIN_BITWIDTH && config->bitwidth <= SOC_ADC_RTC_MAX_BITWIDTH);
bool available_dma_bitwidth = (config->bitwidth >= SOC_ADC_DIGI_MIN_BITWIDTH && config->bitwidth <= SOC_ADC_DIGI_MAX_BITWIDTH);
bool default_bitwidth_mark = (config->bitwidth == ADC_BITWIDTH_DEFAULT);
bool available_bitwidth = (available_oneshot_bitwidth || available_dma_bitwidth || default_bitwidth_mark);
ESP_RETURN_ON_FALSE(available_bitwidth, ESP_ERR_INVALID_ARG, TAG, "invalid bitwidth");
return ESP_OK;
}