esp-idf/components/esp_adc/esp32s2/adc_cali_line_fitting.c
Armando d3be2541de fix(adc): rename ADC_ATTEN_DB_11 to ADC_ATTEN_DB_12
By design, it's 12 dB. There're errors among chips, so the actual
attenuation will be 11dB more or less
2023-11-06 18:55:49 +08:00

249 lines
11 KiB
C

/*
* SPDX-FileCopyrightText: 2019-2023 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdint.h>
#include "assert.h"
#include "esp_types.h"
#include "esp_err.h"
#include "esp_check.h"
#include "esp_heap_caps.h"
#include "esp_efuse.h"
#include "esp_efuse_table.h"
#include "esp_efuse_rtc_table.h"
#include "hal/adc_types.h"
#include "soc/efuse_periph.h"
#include "soc/soc_caps.h"
#include "esp_adc/adc_cali_scheme.h"
#include "adc_cali_interface.h"
const __attribute__((unused)) static char *TAG = "adc_cali";
/* ------------------------ Characterization Constants ---------------------- */
// coeff_a and coeff_b are actually floats
// they are scaled to put them into uint32_t so that the headers do not have to be changed
static const int coeff_a_scaling = 65536;
static const int coeff_b_scaling = 1024;
/* -------------------- Characterization Helper Data Types ------------------ */
typedef struct {
int adc_calib_high;
int adc_calib_low;
} adc_calib_data_ver1_t;
typedef struct {
int adc_calib_high; // the reading of adc ...
int adc_calib_high_voltage; // ... at this voltage (mV)
} adc_calib_data_ver2_t;
typedef struct {
char version_num;
adc_unit_t unit_id;
adc_atten_t atten_level;
union {
adc_calib_data_ver1_t ver1;
adc_calib_data_ver2_t ver2;
} efuse_data;
} adc_calib_parsed_info_t;
/* ------------------------ Context Structure--------------------------- */
typedef struct {
adc_unit_t unit_id; ///< ADC unit
adc_atten_t atten; ///< ADC attenuation
uint32_t coeff_a; ///< Gradient of ADC-Voltage curve
uint32_t coeff_b; ///< Offset of ADC-Voltage curve
} cali_chars_line_fitting_t;
/* ----------------------- Characterization Functions ----------------------- */
static bool prepare_calib_data_for(adc_unit_t unit_id, adc_atten_t atten, adc_calib_parsed_info_t *parsed_data_storage);
/**
* (Used in V1 of calibration scheme)
* The Two Point calibration measures the reading at two specific input voltages, and calculates the (assumed linear) relation
* between input voltage and ADC response. (Response = A * Vinput + B)
* A and B are scaled ints.
* @param high The ADC response at the higher voltage of the corresponding attenuation (600mV, 800mV, 1000mV, 2000mV).
* @param low The ADC response at the lower voltage of the corresponding attenuation (all 250mV).
*
*/
static void characterize_using_two_point(adc_unit_t unit_id,
adc_atten_t atten,
uint32_t high,
uint32_t low,
uint32_t *coeff_a,
uint32_t *coeff_b);
/*
* Estimate the (assumed) linear relationship btwn the measured raw value and the voltage
* with the previously done measurement when the chip was manufactured.
* */
static bool calculate_characterization_coefficients(const adc_calib_parsed_info_t *parsed_data, cali_chars_line_fitting_t *ctx);
/* ------------------------ Interface Functions --------------------------- */
static esp_err_t cali_raw_to_voltage(void *arg, int raw, int *voltage);
/* ------------------------- 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");
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 < SOC_ADC_ATTEN_NUM, ESP_ERR_INVALID_ARG, TAG, "invalid ADC attenuation");
//S2 Oneshot read only supports 13 bits, DMA read only supports 12 bits
ESP_RETURN_ON_FALSE(((config->bitwidth == SOC_ADC_RTC_MAX_BITWIDTH || config->bitwidth == SOC_ADC_DIGI_MAX_BITWIDTH) || config->bitwidth == ADC_BITWIDTH_DEFAULT), ESP_ERR_INVALID_ARG, TAG, "invalid bitwidth");
// current version only accepts encoding ver 1 and ver 2.
uint8_t adc_encoding_version = esp_efuse_rtc_table_read_calib_version();
ESP_RETURN_ON_FALSE(((adc_encoding_version == 1) || (adc_encoding_version == 2)), 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;
adc_calib_parsed_info_t efuse_parsed_data = {0};
bool success = prepare_calib_data_for(config->unit_id, config->atten, &efuse_parsed_data);
assert(success);
success = calculate_characterization_coefficients(&efuse_parsed_data, chars);
assert(success);
ESP_LOGD(TAG, "adc%d (atten leven %d) calibration done: A:%" PRId32" B:%" PRId32, config->unit_id, config->atten, chars->coeff_a, chars->coeff_b);
chars->unit_id = config->unit_id;
chars->atten = config->atten;
*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 / coeff_b_scaling;
return ESP_OK;
}
/* ----------------------- Characterization Functions ----------------------- */
static bool prepare_calib_data_for(adc_unit_t unit_id, adc_atten_t atten, adc_calib_parsed_info_t *parsed_data_storage)
{
int version_num = esp_efuse_rtc_table_read_calib_version();
int tag;
parsed_data_storage->version_num = version_num;
parsed_data_storage->unit_id = unit_id;
parsed_data_storage->atten_level = atten;
switch (version_num) {
case 1:
// note: use the unit_id as in hal, which start from 0.
tag = esp_efuse_rtc_table_get_tag(version_num, unit_id, atten, RTCCALIB_V1_PARAM_VLOW);
parsed_data_storage->efuse_data.ver1.adc_calib_low = esp_efuse_rtc_table_get_parsed_efuse_value(tag, false);
tag = esp_efuse_rtc_table_get_tag(version_num, unit_id, atten, RTCCALIB_V1_PARAM_VHIGH);
parsed_data_storage->efuse_data.ver1.adc_calib_high = esp_efuse_rtc_table_get_parsed_efuse_value(tag, false);
break;
case 2:
tag = esp_efuse_rtc_table_get_tag(version_num, unit_id, atten, RTCCALIB_V2_PARAM_VHIGH);
parsed_data_storage->efuse_data.ver2.adc_calib_high = esp_efuse_rtc_table_get_parsed_efuse_value(tag, false);
switch (parsed_data_storage->atten_level) {
case ADC_ATTEN_DB_0:
parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 600;
break;
case ADC_ATTEN_DB_2_5:
parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 800;
break;
case ADC_ATTEN_DB_6:
parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 1000;
break;
case ADC_ATTEN_DB_12:
parsed_data_storage->efuse_data.ver2.adc_calib_high_voltage = 2000;
break;
default:
break;
}
break;
default:
// fall back to case 1 with zeros as params.
parsed_data_storage->version_num = 1;
tag = esp_efuse_rtc_table_get_tag(version_num, unit_id, atten, RTCCALIB_V1_PARAM_VLOW);
parsed_data_storage->efuse_data.ver1.adc_calib_high = esp_efuse_rtc_table_get_parsed_efuse_value(tag, true);
tag = esp_efuse_rtc_table_get_tag(version_num, unit_id, atten, RTCCALIB_V1_PARAM_VHIGH);
parsed_data_storage->efuse_data.ver1.adc_calib_low = esp_efuse_rtc_table_get_parsed_efuse_value(tag, true);
break;
}
return true;
}
/**
* (Used in V1 of calibration scheme)
* The Two Point calibration measures the reading at two specific input voltages, and calculates the (assumed linear) relation
* between input voltage and ADC response. (Response = A * Vinput + B)
* A and B are scaled ints.
* @param high The ADC response at the higher voltage of the corresponding attenuation (600mV, 800mV, 1000mV, 2000mV).
* @param low The ADC response at the lower voltage of the corresponding attenuation (all 250mV).
*
*/
static void characterize_using_two_point(adc_unit_t unit_id,
adc_atten_t atten,
uint32_t high,
uint32_t low,
uint32_t *coeff_a,
uint32_t *coeff_b)
{
// once we have recovered the reference high(Dhigh) and low(Dlow) readings, we can calculate a and b from
// the measured high and low readings
static const uint32_t v_high[] = {600, 800, 1000, 2000};
static const uint32_t v_low = 250;
*coeff_a = coeff_a_scaling * (v_high[atten] - v_low) / (high - low);
*coeff_b = coeff_b_scaling * (v_low * high - v_high[atten] * low) / (high - low);
}
/*
* Estimate the (assumed) linear relationship btwn the measured raw value and the voltage
* with the previously done measurement when the chip was manufactured.
* */
static bool calculate_characterization_coefficients(const adc_calib_parsed_info_t *parsed_data, cali_chars_line_fitting_t *ctx)
{
switch (parsed_data->version_num) {
case 1:
ESP_LOGD(TAG, "Calib V1, low%dmV, high%dmV", parsed_data->efuse_data.ver1.adc_calib_low, parsed_data->efuse_data.ver1.adc_calib_high);
characterize_using_two_point(parsed_data->unit_id, parsed_data->atten_level,
parsed_data->efuse_data.ver1.adc_calib_high, parsed_data->efuse_data.ver1.adc_calib_low,
&(ctx->coeff_a), &(ctx->coeff_b));
break;
case 2:
ESP_LOGD(TAG, "Calib V2, volt%dmV", parsed_data->efuse_data.ver2.adc_calib_high);
ctx->coeff_a = coeff_a_scaling * parsed_data->efuse_data.ver2.adc_calib_high_voltage /
parsed_data->efuse_data.ver2.adc_calib_high;
ctx->coeff_b = 0;
break;
default:
return false;
break;
}
return true;
}