1 /*
2 * SPDX-FileCopyrightText: 2020-2021 Espressif Systems (Shanghai) CO LTD
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <stdint.h>
8 #include <stdbool.h>
9 #include <string.h>
10 #include "esp_types.h"
11 #include "esp_err.h"
12 #include "esp_log.h"
13 #include "esp_check.h"
14 #include "hal/adc_types.h"
15 #include "esp_efuse_rtc_calib.h"
16 #include "hal/adc_types.h"
17 #include "driver/adc_types_legacy.h"
18 #include "esp_adc_cal_types_legacy.h"
19 #include "../esp_adc_cal_internal_legacy.h"
20
21 const static char LOG_TAG[] = "ADC_CALI";
22
23 /* ------------------------ Characterization Constants ---------------------- */
24
25 //coeff_a is actually a float number
26 //it is scaled to put them into uint32_t so that the headers do not have to be changed
27 static const int coeff_a_scaling = 1000000;
28
29 /**
30 * @note Error Calculation
31 * Coefficients for calculating the reading voltage error.
32 * Four sets of coefficients for atten0 ~ atten3 respectively.
33 *
34 * For each item, first element is the Coefficient, second element is the Multiple. (Coefficient / Multiple) is the real coefficient.
35 *
36 * @note {0,0} stands for unused item
37 * @note In case of the overflow, these coeffcients are recorded as Absolute Value
38 * @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);
39 * @note Above formula is rewritten from the original documentation, please note that the coefficients are re-ordered.
40 */
41 const static uint64_t adc1_error_coef_atten[4][5][2] = {
42 {{27856531419538344, 1e16}, {50871540569528, 1e16}, {9798249589, 1e15}, {0, 0}, {0, 0}}, //ADC1 atten0
43 {{29831022915028695, 1e16}, {49393185868806, 1e16}, {101379430548, 1e16}, {0, 0}, {0, 0}}, //ADC1 atten1
44 {{23285545746296417, 1e16}, {147640181047414, 1e16}, {208385525314, 1e16}, {0, 0}, {0, 0}}, //ADC1 atten2
45 {{644403418269478, 1e15}, {644334888647536, 1e16}, {1297891447611, 1e16}, {70769718, 1e15}, {13515, 1e15}} //ADC1 atten3
46 };
47 const static uint64_t adc2_error_coef_atten[4][5][2] = {
48 {{25668651654328927, 1e16}, {1353548869615, 1e16}, {36615265189, 1e16}, {0, 0}, {0, 0}}, //ADC2 atten0
49 {{23690184690298404, 1e16}, {66319894226185, 1e16}, {118964995959, 1e16}, {0, 0}, {0, 0}}, //ADC2 atten1
50 {{9452499397020617, 1e16}, {200996773954387, 1e16}, {259011467956, 1e16}, {0, 0}, {0, 0}}, //ADC2 atten2
51 {{12247719764336924,1e16}, {755717904943462, 1e16}, {1478791187119, 1e16}, {79672528, 1e15}, {15038, 1e15}} //ADC2 atten3
52 };
53 /**
54 * Term sign
55 */
56 const static int32_t adc1_error_sign[4][5] = {
57 {-1, -1, 1, 0, 0}, //ADC1 atten0
58 {-1, -1, 1, 0, 0}, //ADC1 atten1
59 {-1, -1, 1, 0, 0}, //ADC1 atten2
60 {-1, -1, 1, -1, 1} //ADC1 atten3
61 };
62 const static int32_t adc2_error_sign[4][5] = {
63 {-1, 1, 1, 0, 0}, //ADC2 atten0
64 {-1, -1, 1, 0, 0}, //ADC2 atten1
65 {-1, -1, 1, 0, 0}, //ADC2 atten2
66 { 1, -1, 1, -1, 1} //ADC2 atten3
67 };
68
69 /* -------------------- Characterization Helper Data Types ------------------ */
70 typedef struct {
71 uint32_t voltage;
72 uint32_t digi;
73 } adc_calib_data_ver1_t;
74
75 typedef struct {
76 char version_num;
77 adc_unit_t adc_num;
78 adc_atten_t atten_level;
79 union {
80 adc_calib_data_ver1_t ver1;
81 } ref_data;
82 } adc_calib_info_t;
83
84
85 //To get the reference point (Dout, Vin)
get_reference_point(int version_num,adc_unit_t adc_num,adc_atten_t atten,adc_calib_info_t * calib_info)86 static esp_err_t get_reference_point(int version_num, adc_unit_t adc_num, adc_atten_t atten, adc_calib_info_t *calib_info)
87 {
88 assert(version_num == 1);
89 esp_err_t ret;
90
91 calib_info->version_num = version_num;
92 calib_info->adc_num = adc_num;
93 calib_info->atten_level = atten;
94
95 uint32_t voltage = 0;
96 uint32_t digi = 0;
97 ret = esp_efuse_rtc_calib_get_cal_voltage(version_num, adc_num, atten, &digi, &voltage);
98 assert(ret == ESP_OK);
99 calib_info->ref_data.ver1.voltage = voltage;
100 calib_info->ref_data.ver1.digi = digi;
101 return ret;
102 }
103
esp_adc_cal_check_efuse(esp_adc_cal_value_t source)104 esp_err_t esp_adc_cal_check_efuse(esp_adc_cal_value_t source)
105 {
106 if (source != ESP_ADC_CAL_VAL_EFUSE_TP_FIT) {
107 return ESP_ERR_NOT_SUPPORTED;
108 }
109 uint8_t adc_encoding_version = esp_efuse_rtc_calib_get_ver();
110 if (adc_encoding_version != 1) {
111 // current version only accepts encoding ver 1.
112 return ESP_ERR_INVALID_VERSION;
113 }
114 return ESP_OK;
115 }
116
117 /*
118 * Get an expected linear relationship btwn Vin and Dout
119 */
calculate_characterization_coefficients(const adc_calib_info_t * parsed_data,esp_adc_cal_characteristics_t * chars)120 static void calculate_characterization_coefficients(const adc_calib_info_t *parsed_data, esp_adc_cal_characteristics_t *chars)
121 {
122 chars->coeff_a = coeff_a_scaling * parsed_data->ref_data.ver1.voltage / parsed_data->ref_data.ver1.digi;
123 chars->coeff_b = 0;
124 ESP_LOGV(LOG_TAG, "Calib V1, Cal Voltage = %"PRId32", Digi out = %"PRId32", Coef_a = %"PRId32"\n", parsed_data->ref_data.ver1.voltage, parsed_data->ref_data.ver1.digi, chars->coeff_a);
125 }
126
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)127 esp_adc_cal_value_t esp_adc_cal_characterize(adc_unit_t adc_num,
128 adc_atten_t atten,
129 adc_bits_width_t bit_width,
130 uint32_t default_vref,
131 esp_adc_cal_characteristics_t *chars)
132 {
133 (void) default_vref;
134
135 // Check parameters
136 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");
137 ESP_RETURN_ON_FALSE(chars != NULL, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "Ivalid characteristic");
138 ESP_RETURN_ON_FALSE(atten < SOC_ADC_ATTEN_NUM, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "Invalid attenuation");
139
140 int version_num = esp_efuse_rtc_calib_get_ver();
141 ESP_RETURN_ON_FALSE(version_num == 1, ESP_ADC_CAL_VAL_NOT_SUPPORTED, LOG_TAG, "No calibration efuse burnt");
142
143 memset(chars, 0, sizeof(esp_adc_cal_characteristics_t));
144
145 adc_calib_info_t calib_info = {0};
146 // make sure adc is calibrated.
147 get_reference_point(version_num, adc_num, atten, &calib_info);
148 calculate_characterization_coefficients(&calib_info, chars);
149
150 // Initialize remaining fields
151 chars->adc_num = adc_num;
152 chars->atten = atten;
153 chars->bit_width = bit_width;
154
155 return ESP_ADC_CAL_VAL_EFUSE_TP_FIT;
156 }
157
esp_adc_cal_raw_to_voltage(uint32_t adc_reading,const esp_adc_cal_characteristics_t * chars)158 uint32_t esp_adc_cal_raw_to_voltage(uint32_t adc_reading, const esp_adc_cal_characteristics_t *chars)
159 {
160 assert(chars != NULL);
161
162 //ADC reading won't exceed 4096. Otherwise the raw reading result is wrong, the next calculation will overflow.
163 assert(adc_reading < 4096);
164
165 uint32_t voltage = 0;
166 int32_t error = 0;
167 uint64_t v_cali_1 = 0;
168
169 //raw * gradient * 1000000
170 v_cali_1 = (uint64_t)adc_reading * chars->coeff_a;
171 //convert to real number
172 v_cali_1 = v_cali_1 / coeff_a_scaling;
173 ESP_LOGV(LOG_TAG, "v_cali_1 is %llu", v_cali_1);
174
175 //Curve Fitting error correction
176 esp_adc_error_calc_param_t param = {
177 .v_cali_input = v_cali_1,
178 .term_num = (chars->atten == 3) ? 5 : 3,
179 .coeff = (chars->adc_num == ADC_UNIT_1) ? &adc1_error_coef_atten : &adc2_error_coef_atten,
180 .sign = (chars->adc_num == ADC_UNIT_1) ? &adc1_error_sign : &adc2_error_sign,
181 };
182 error = esp_adc_cal_get_reading_error(¶m, chars->atten);
183
184 voltage = (int32_t)v_cali_1 - error;
185
186 return voltage;
187 }
188
