/* * SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Apache-2.0 */ #include #include "sdkconfig.h" #include "assert.h" #include "esp_types.h" #include "esp_err.h" #include "esp_check.h" #include "esp_heap_caps.h" #include "hal/adc_types.h" #include "hal/efuse_ll.h" #include "soc/soc_caps.h" #include "esp_adc/adc_cali_scheme.h" #include "adc_cali_interface.h" /* ----------------------------- Configuration ------------------------------ */ #ifdef CONFIG_ADC_CALI_EFUSE_TP_ENABLE #define EFUSE_TP_ENABLED 1 #else #define EFUSE_TP_ENABLED 0 #endif #ifdef CONFIG_ADC_CALI_EFUSE_VREF_ENABLE #define EFUSE_VREF_ENABLED 1 #else #define EFUSE_VREF_ENABLED 0 #endif #ifdef CONFIG_ADC_CALI_LUT_ENABLE #define LUT_ENABLED 1 #else #define LUT_ENABLED 0 #endif /* ESP32s with both Two Point Values and Vref burned into eFuse are required to * also burn the EFUSE_BLK3_PART_RESERVE flag. A limited set of ESP32s * (not available through regular sales channel) DO NOT have the * EFUSE_BLK3_PART_RESERVE burned. Moreover, this set of ESP32s represents Vref * in Two's Complement format. If this is the case, modify the preprocessor * definitions below as follows... * #define CHECK_BLK3_FLAG 0 //Do not check BLK3 flag as it is not burned * #define VREF_FORMAT 1 //eFuse Vref is in Two's Complement format */ #define CHECK_BLK3_FLAG 1 #define VREF_FORMAT 0 /* ------------------------------ eFuse Access ----------------------------- */ #define VREF_MASK 0x1F #define VREF_STEP_SIZE 7 #define VREF_OFFSET 1100 #define TP_LOW1_OFFSET 278 #define TP_LOW2_OFFSET 421 #define TP_LOW_MASK 0x7F #define TP_LOW_VOLTAGE 150 #define TP_HIGH1_OFFSET 3265 #define TP_HIGH2_OFFSET 3406 #define TP_HIGH_MASK 0x1FF #define TP_HIGH_VOLTAGE 850 #define TP_STEP_SIZE 4 /* ----------------------- Raw to Voltage Constants ------------------------- */ #define LIN_COEFF_A_SCALE 65536 #define LIN_COEFF_A_ROUND (LIN_COEFF_A_SCALE/2) #define LUT_VREF_LOW 1000 #define LUT_VREF_HIGH 1200 #define LUT_ADC_STEP_SIZE 64 #define LUT_POINTS 20 #define LUT_LOW_THRESH 2880 #define LUT_HIGH_THRESH (LUT_LOW_THRESH + LUT_ADC_STEP_SIZE) #define ADC_12_BIT_RES 4096 /* ------------------------ Characterization Constants ---------------------- */ static const uint32_t adc1_tp_atten_scale[4] = {65504, 86975, 120389, 224310}; static const uint32_t adc2_tp_atten_scale[4] = {65467, 86861, 120416, 224708}; static const uint32_t adc1_tp_atten_offset[4] = {0, 1, 27, 54}; static const uint32_t adc2_tp_atten_offset[4] = {0, 9, 26, 66}; static const uint32_t adc1_vref_atten_scale[4] = {57431, 76236, 105481, 196602}; static const uint32_t adc2_vref_atten_scale[4] = {57236, 76175, 105678, 197170}; static const uint32_t adc1_vref_atten_offset[4] = {75, 78, 107, 142}; static const uint32_t adc2_vref_atten_offset[4] = {63, 66, 89, 128}; //20 Point lookup tables, covering ADC readings from 2880 to 4096, step size of 64 static const uint32_t lut_adc1_low[LUT_POINTS] = {2240, 2297, 2352, 2405, 2457, 2512, 2564, 2616, 2664, 2709, 2754, 2795, 2832, 2868, 2903, 2937, 2969, 3000, 3030, 3060}; static const uint32_t lut_adc1_high[LUT_POINTS] = {2667, 2706, 2745, 2780, 2813, 2844, 2873, 2901, 2928, 2956, 2982, 3006, 3032, 3059, 3084, 3110, 3135, 3160, 3184, 3209}; static const uint32_t lut_adc2_low[LUT_POINTS] = {2238, 2293, 2347, 2399, 2451, 2507, 2561, 2613, 2662, 2710, 2754, 2792, 2831, 2869, 2904, 2937, 2968, 2999, 3029, 3059}; static const uint32_t lut_adc2_high[LUT_POINTS] = {2657, 2698, 2738, 2774, 2807, 2838, 2867, 2894, 2921, 2946, 2971, 2996, 3020, 3043, 3067, 3092, 3116, 3139, 3162, 3185}; const __attribute__((unused)) static char *TAG = "adc_cali"; /* ----------------------- EFuse Access Functions --------------------------- */ static bool check_efuse_vref(void); static bool check_efuse_tp(void); static inline int decode_bits(uint32_t bits, uint32_t mask, bool is_twos_compl); static uint32_t read_efuse_vref(void); static uint32_t read_efuse_tp_low(adc_unit_t unit_id); static uint32_t read_efuse_tp_high(adc_unit_t unit_id); /* ----------------------- Characterization Functions ----------------------- */ 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); static void characterize_using_vref(adc_unit_t unit_id, adc_atten_t atten, uint32_t vref, uint32_t *coeff_a, uint32_t *coeff_b); /* ------------------------ Conversion Functions --------------------------- */ static uint32_t calculate_voltage_linear(uint32_t adc_reading, uint32_t coeff_a, uint32_t coeff_b); //Only call when ADC reading is above threshold static uint32_t calculate_voltage_lut(uint32_t adc, uint32_t vref, const uint32_t *low_vref_curve, const uint32_t *high_vref_curve); static inline uint32_t interpolate_two_points(uint32_t y1, uint32_t y2, uint32_t x_step, uint32_t x) { //Interpolate between two points (x1,y1) (x2,y2) between 'lower' and 'upper' separated by 'step' return ((y1 * x_step) + (y2 * x) - (y1 * x) + (x_step / 2)) / x_step; } /* ------------------------ Interface Functions --------------------------- */ static esp_err_t cali_raw_to_voltage(void *arg, int raw, int *voltage); /* ------------------------ Context Structure--------------------------- */ typedef struct { adc_unit_t unit_id; ///< ADC unit adc_atten_t atten; ///< ADC attenuation adc_bitwidth_t bitwidth; ///< ADC bit width uint32_t coeff_a; ///< Gradient of ADC-Voltage curve uint32_t coeff_b; ///< Offset of ADC-Voltage curve uint32_t vref; ///< Vref used by lookup table const uint32_t *low_curve; ///< Pointer to low Vref curve of lookup table (NULL if unused) const uint32_t *high_curve; ///< Pointer to high Vref curve of lookup table (NULL if unused) adc_cali_line_fitting_efuse_val_t efuse_val; ///< Type of calibration value used in characterization } cali_chars_line_fitting_t; /* ------------------------- 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 && config, ESP_ERR_INVALID_ARG, TAG, "invalid argument: 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"); ESP_RETURN_ON_FALSE(((config->bitwidth >= SOC_ADC_RTC_MIN_BITWIDTH && config->bitwidth <= SOC_ADC_RTC_MAX_BITWIDTH) || config->bitwidth == ADC_BITWIDTH_DEFAULT), ESP_ERR_INVALID_ARG, TAG, "invalid bitwidth"); 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"); //Check eFuse if enabled to do so if (check_efuse_tp() && EFUSE_TP_ENABLED) { //Characterize based on Two Point values chars->efuse_val = ADC_CALI_LINE_FITTING_EFUSE_VAL_EFUSE_TP; //Characterize based on Two Point values uint32_t high = read_efuse_tp_high(config->unit_id); uint32_t low = read_efuse_tp_low(config->unit_id); characterize_using_two_point(config->unit_id, config->atten, high, low, &chars->coeff_a, &chars->coeff_b); } else if (check_efuse_vref() && EFUSE_VREF_ENABLED) { //Characterize based on eFuse Vref chars->efuse_val = ADC_CALI_LINE_FITTING_EFUSE_VAL_EFUSE_VREF; chars->vref = read_efuse_vref(); characterize_using_vref(config->unit_id, config->atten, chars->vref, &chars->coeff_a, &chars->coeff_b); } else { //Characterized based on default Vref chars->efuse_val = ADC_CALI_LINE_FITTING_EFUSE_VAL_DEFAULT_VREF; ESP_GOTO_ON_FALSE(config->default_vref, ESP_ERR_INVALID_ARG, err, TAG, "default vref didn't set"); chars->vref = config->default_vref; characterize_using_vref(config->unit_id, config->atten, chars->vref, &chars->coeff_a, &chars->coeff_b); } chars->unit_id = config->unit_id; chars->atten = config->atten; chars->bitwidth = (config->bitwidth == ADC_BITWIDTH_DEFAULT) ? ADC_BITWIDTH_12 : config->bitwidth; //Initialize fields for lookup table if necessary if (LUT_ENABLED && config->atten == ADC_ATTEN_DB_11) { chars->low_curve = (config->unit_id == ADC_UNIT_1) ? lut_adc1_low : lut_adc2_low; chars->high_curve = (config->unit_id == ADC_UNIT_1) ? lut_adc1_high : lut_adc2_high; } else { chars->low_curve = NULL; chars->high_curve = NULL; } scheme->raw_to_voltage = cali_raw_to_voltage; scheme->ctx = chars; *ret_handle = scheme; return ESP_OK; err: if (scheme) { free(scheme); } return ret; } esp_err_t adc_cali_scheme_line_fitting_check_efuse(adc_cali_line_fitting_efuse_val_t *cali_val) { ESP_RETURN_ON_FALSE(cali_val, ESP_ERR_INVALID_ARG, TAG, "invalid argument: null pointer"); if (check_efuse_tp()) { *cali_val = ADC_CALI_LINE_FITTING_EFUSE_VAL_EFUSE_TP; } else if (check_efuse_vref()) { *cali_val = ADC_CALI_LINE_FITTING_EFUSE_VAL_EFUSE_VREF; } else { *cali_val = ADC_CALI_LINE_FITTING_EFUSE_VAL_DEFAULT_VREF; } return ESP_OK; } 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; //Scale adc_rading if not 12 bits wide raw = (raw << (ADC_BITWIDTH_12 - ctx->bitwidth)); if (raw > ADC_12_BIT_RES - 1) { raw = ADC_12_BIT_RES - 1; //Set to 12bit res max } if (LUT_ENABLED && (ctx->atten == ADC_ATTEN_DB_11) && (raw >= LUT_LOW_THRESH)) { //Check if in non-linear region //Use lookup table to get voltage in non linear portion of ADC_ATTEN_DB_11 uint32_t lut_voltage = calculate_voltage_lut(raw, ctx->vref, ctx->low_curve, ctx->high_curve); if (raw <= LUT_HIGH_THRESH) { //If ADC is transitioning from linear region to non-linear region //Linearly interpolate between linear voltage and lut voltage uint32_t linear_voltage = calculate_voltage_linear(raw, ctx->coeff_a, ctx->coeff_b); *voltage = interpolate_two_points(linear_voltage, lut_voltage, LUT_ADC_STEP_SIZE, (raw - LUT_LOW_THRESH)); } else { *voltage = lut_voltage; } } else { *voltage = calculate_voltage_linear(raw, ctx->coeff_a, ctx->coeff_b); } return ESP_OK; } /* ----------------------- EFuse Access Functions --------------------------- */ static bool check_efuse_vref(void) { //Check if Vref is burned in eFuse return (efuse_ll_get_adc_vref() != 0) ? true : false; } static bool check_efuse_tp(void) { //Check if Two Point values are burned in eFuse if (CHECK_BLK3_FLAG && (efuse_ll_get_blk3_part_reserve() == 0)) { return false; } //All TP cal values must be non zero return efuse_ll_get_adc1_tp_low() && efuse_ll_get_adc2_tp_low() && efuse_ll_get_adc1_tp_high() && efuse_ll_get_adc2_tp_high(); } static inline int decode_bits(uint32_t bits, uint32_t mask, bool is_twos_compl) { int ret; if (bits & (~(mask >> 1) & mask)) { //Check sign bit (MSB of mask) //Negative if (is_twos_compl) { ret = -(((~bits) + 1) & (mask >> 1)); //2's complement } else { ret = -(bits & (mask >> 1)); //Sign-magnitude } } else { //Positive ret = bits & (mask >> 1); } return ret; } static uint32_t read_efuse_vref(void) { //eFuse stores deviation from ideal reference voltage uint32_t ret = VREF_OFFSET; //Ideal vref uint32_t bits = efuse_ll_get_adc_vref(); ret += decode_bits(bits, VREF_MASK, VREF_FORMAT) * VREF_STEP_SIZE; return ret; //ADC Vref in mV } static uint32_t read_efuse_tp_low(adc_unit_t unit_id) { //ADC reading at 150mV stored in two's complement format uint32_t ret; uint32_t bits; if (unit_id == ADC_UNIT_1) { ret = TP_LOW1_OFFSET; bits = efuse_ll_get_adc1_tp_low(); } else { ret = TP_LOW2_OFFSET; bits = efuse_ll_get_adc2_tp_low(); } ret += decode_bits(bits, TP_LOW_MASK, true) * TP_STEP_SIZE; return ret; //Reading of ADC at 150mV } static uint32_t read_efuse_tp_high(adc_unit_t unit_id) { //ADC reading at 850mV stored in two's complement format uint32_t ret; uint32_t bits; if (unit_id == ADC_UNIT_1) { ret = TP_HIGH1_OFFSET; bits = efuse_ll_get_adc1_tp_high(); } else { ret = TP_HIGH2_OFFSET; bits = efuse_ll_get_adc2_tp_high(); } ret += decode_bits(bits, TP_HIGH_MASK, true) * TP_STEP_SIZE; return ret; //Reading of ADC at 850mV } /* ----------------------- Characterization Functions ----------------------- */ 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) { const uint32_t *atten_scales; const uint32_t *atten_offsets; if (unit_id == ADC_UNIT_1) { //Using ADC 1 atten_scales = adc1_tp_atten_scale; atten_offsets = adc1_tp_atten_offset; } else { //Using ADC 2 atten_scales = adc2_tp_atten_scale; atten_offsets = adc2_tp_atten_offset; } //Characterize ADC-Voltage curve as y = (coeff_a * x) + coeff_b uint32_t delta_x = high - low; uint32_t delta_v = TP_HIGH_VOLTAGE - TP_LOW_VOLTAGE; //Where coeff_a = (delta_v/delta_x) * atten_scale *coeff_a = (delta_v * atten_scales[atten] + (delta_x / 2)) / delta_x; //+(delta_x/2) for rounding //Where coeff_b = high_v - ((delta_v/delta_x) * high_x) + atten_offset *coeff_b = TP_HIGH_VOLTAGE - ((delta_v * high + (delta_x / 2)) / delta_x) + atten_offsets[atten]; } static void characterize_using_vref(adc_unit_t unit_id, adc_atten_t atten, uint32_t vref, uint32_t *coeff_a, uint32_t *coeff_b) { const uint32_t *atten_scales; const uint32_t *atten_offsets; if (unit_id == ADC_UNIT_1) { //Using ADC 1 atten_scales = adc1_vref_atten_scale; atten_offsets = adc1_vref_atten_offset; } else { //Using ADC 2 atten_scales = adc2_vref_atten_scale; atten_offsets = adc2_vref_atten_offset; } //Characterize ADC-Voltage curve as y = (coeff_a * x) + coeff_b //Where coeff_a = (vref/4096) * atten_scale *coeff_a = (vref * atten_scales[atten]) / (ADC_12_BIT_RES); *coeff_b = atten_offsets[atten]; } /* ------------------------ Conversion Functions --------------------------- */ static uint32_t calculate_voltage_linear(uint32_t adc_reading, uint32_t coeff_a, uint32_t coeff_b) { //Where voltage = coeff_a * adc_reading + coeff_b return (((coeff_a * adc_reading) + LIN_COEFF_A_ROUND) / LIN_COEFF_A_SCALE) + coeff_b; } //Only call when ADC reading is above threshold static uint32_t calculate_voltage_lut(uint32_t adc, uint32_t vref, const uint32_t *low_vref_curve, const uint32_t *high_vref_curve) { //Get index of lower bound points of LUT uint32_t i = (adc - LUT_LOW_THRESH) / LUT_ADC_STEP_SIZE; //Let the X Axis be Vref, Y axis be ADC reading, and Z be voltage int x2dist = LUT_VREF_HIGH - vref; //(x2 - x) int x1dist = vref - LUT_VREF_LOW; //(x - x1) int y2dist = ((i + 1) * LUT_ADC_STEP_SIZE) + LUT_LOW_THRESH - adc; //(y2 - y) int y1dist = adc - ((i * LUT_ADC_STEP_SIZE) + LUT_LOW_THRESH); //(y - y1) //For points for bilinear interpolation int q11 = low_vref_curve[i]; //Lower bound point of low_vref_curve int q12 = low_vref_curve[i + 1]; //Upper bound point of low_vref_curve int q21 = high_vref_curve[i]; //Lower bound point of high_vref_curve int q22 = high_vref_curve[i + 1]; //Upper bound point of high_vref_curve //Bilinear interpolation //Where z = 1/((x2-x1)*(y2-y1)) * ( (q11*x2dist*y2dist) + (q21*x1dist*y2dist) + (q12*x2dist*y1dist) + (q22*x1dist*y1dist) ) int voltage = (q11 * x2dist * y2dist) + (q21 * x1dist * y2dist) + (q12 * x2dist * y1dist) + (q22 * x1dist * y1dist); voltage += ((LUT_VREF_HIGH - LUT_VREF_LOW) * LUT_ADC_STEP_SIZE) / 2; //Integer division rounding voltage /= ((LUT_VREF_HIGH - LUT_VREF_LOW) * LUT_ADC_STEP_SIZE); //Divide by ((x2-x1)*(y2-y1)) return (uint32_t)voltage; }