adc: upgrade adc calibration algorithm to version 2 on c3

components/esp_adc_cal/esp32c3/esp_adc_cal.c

@@ -0,0 +1,172 @@
+/*
+ * 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;
+}