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4cbed9b364
ESP32 lets the user choose from using Vref, Lookup Table, and Two-Point Calibration. In ESP32S2 only two-point calibration is supported. This commit support these changes in idf. Closes https://github.com/espressif/esp-idf/issues/5455
294 lines
12 KiB
C
294 lines
12 KiB
C
// Copyright 2019-2020 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <stdint.h>
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#include "esp_types.h"
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#include "driver/adc.h"
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#include "soc/efuse_periph.h"
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#include "esp_err.h"
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#include "assert.h"
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#include "esp_adc_cal.h"
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#include "esp_efuse.h"
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#define ADC_CAL_CHECK(cond, ret) ({ \
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if(!(cond)){ \
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return ret; \
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} \
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})
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/* ------------------------ Characterization Constants ---------------------- */
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#define ADC_CHAR_VERSION1_EFUSEVAL 1
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static const uint32_t adc1_D_mean_low[] = {2231, 1643, 1290, 701};
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static const uint32_t adc2_D_mean_low[] = {2305, 1693, 1343, 723};
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static const uint32_t adc1_D_mean_high[] = {5775, 5692, 5725, 6209};
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static const uint32_t adc2_D_mean_high[] = {5817, 5703, 5731, 6157};
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static const int Dlow_data_length = 6;
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static const int Dhigh_data_length = 8;
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static const int adc_efuse_block = 2;
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static const int adc_calib_ver_block = 2;
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static const int adc_calib_ver_word_loc = 4;
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static const int adc_calib_ver_offset = 4;
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static const int adc_calib_ver_len = 3;
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static const int adc1_atten0_Dlow_word_loc = 6;
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static const int adc2_atten0_Dlow_word_loc = 7;
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static const int adc1_atten0_Dhigh_word_loc = 4;
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static const int adc2_atten0_Dhigh_word_loc = 5;
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static const int adc1_atten0_Dlow_offset = 16;
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static const int adc2_atten0_Dlow_offset = 8;
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static const int adc1_atten0_Dhigh_offset = 16;
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static const int adc2_atten0_Dhigh_offset = 16;
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/* ----------------------- EFuse Access Functions --------------------------- */
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/**
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* Convenience function that reads a few bits from efuse and assembles them.
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* For example, if the contents of the EFuse are:
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* Word2: 0x1234 Word3:0x5678
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* Then, setting base=2, offset=24, len=24 will yield 0x456.
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* @note does not check for boundaries, make sure parameters are correct
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* @param blk EFuse Block
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* @param base the starting word
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* @param offset the bit offset in the starting word
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* @param bit how many consecutive bits to fetch
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* @return the assembled number
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*/
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static uint32_t get_consecutive_bits_from_blk(int blk, uint32_t base, int offset, int len)
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{
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base += offset / 32;
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offset %= 32;
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if (offset + len <= 32 || base == 7) {
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uint32_t result = esp_efuse_read_reg(blk, base);
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result <<= (32 - offset - len);
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result >>= (32 - len);
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return result;
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} else {
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// need to fetch both bytes.
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uint64_t result = ((uint64_t)esp_efuse_read_reg(blk, base + 1) << 32) + esp_efuse_read_reg(blk, base);
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result &= ((uint64_t)1 << (offset + len)) - 1;
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result >>= offset;
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return result;
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}
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}
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/**
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* To save space in EFuse, the calibration values for adc are compressed.
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* The compression scheme is: for X bits of ADC Efuse data,
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* The actual ADC reading is: BASE_VALUE + 4*ADC_OFFSET
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* where ADC_OFFSET = bits X-1:0 in Efuse, the highest bit is the sign bit (0:+, 1:-).
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*
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* The following functions do this conversion.
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* @param efuse_val raw values read from efuse.
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* @param adc_num Specifies the channel number. The 2 adc channels each have different calibration values.
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* @param attem Specifies the attenuation. Different attenuation level have different calibration values.
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*/
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static uint32_t efuse_low_val_to_d(uint16_t efuse_val, adc_unit_t adc_num, adc_atten_t atten)
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{
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// efuse_val is 5 bits + 6th sign bit.
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int32_t rawoffsetval = efuse_val & ((1 << (Dlow_data_length - 1)) - 1);
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// if the sign bit is 1, it means it is a negative sign.
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int32_t offset = (efuse_val & (1 << (Dlow_data_length - 1))) ? (-rawoffsetval * 4) : (rawoffsetval * 4);
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if (adc_num == ADC_UNIT_1) {
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return offset + adc1_D_mean_low[atten - ADC_ATTEN_DB_0];
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} else {
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return offset + adc2_D_mean_low[atten - ADC_ATTEN_DB_0];
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}
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}
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static uint32_t efuse_high_val_to_d (uint16_t efuse_val, adc_unit_t adc_num, adc_atten_t atten)
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{
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// efuse_val is 7 bits + 8th sign bit.
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int32_t rawoffsetval = efuse_val & ((1 << (Dhigh_data_length - 1)) - 1);
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int32_t offset = (efuse_val & (1 << (Dhigh_data_length - 1))) ? (-rawoffsetval * 4) : (rawoffsetval * 4);
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if (adc_num == ADC_UNIT_1) {
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return offset + adc1_D_mean_high[atten - ADC_ATTEN_DB_0];
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} else {
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return offset + adc2_D_mean_high[atten - ADC_ATTEN_DB_0];
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}
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}
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/**
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* To save space in EFuse, the calibration values for adc are compressed.
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* The compression scheme is: for X bits of ADC Efuse data,
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* The actual ADC reading is: BASE_VALUE + 4*ADC_OFFSET
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* where ADC_OFFSET = bits X-1:0 in Efuse, the highest bit is the sign bit (0:+, 1:-).
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*
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* The following functions do the reading.
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* @param efuse_val raw values read from efuse.
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* @param adc_num Specifies the channel number. The 2 adc channels each have different calibration values.
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* @param attem Specifies the attenuation. Different attenuation level have different calibration values.
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*/
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static uint32_t read_efuse_tp_low(adc_unit_t adc_num, adc_atten_t atten)
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{
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// this fcn retrieves and decodes the calibration value stored in efuse.
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uint32_t base;
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int offset;
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// may need to move magic numbers out
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if (adc_num == ADC_UNIT_1) {
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// the first value is at the 16th bit of the 6th word of the efuse block 2, each value is 6 bits long.
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base = adc1_atten0_Dlow_word_loc;
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offset = adc1_atten0_Dlow_offset + Dlow_data_length * (atten - ADC_ATTEN_DB_0);
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} else {
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// the first value is at the 8th bit of the 7th word of the efuse block 2, each value is 6 bits long.
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base = adc2_atten0_Dlow_word_loc;
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offset = adc2_atten0_Dlow_offset + Dlow_data_length * (atten - ADC_ATTEN_DB_0);
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}
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uint32_t read_result = get_consecutive_bits_from_blk(adc_efuse_block, base, offset, Dlow_data_length);
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return read_result;
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}
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static uint32_t read_efuse_tp_high(adc_unit_t adc_num, adc_atten_t atten)
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{
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// this fcn retrieves and decodes the calibration value stored in efuse.
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uint32_t base;
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int offset;
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if (adc_num == ADC_UNIT_1) {
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// the first value is at the 16th bit of the 4th word of the efuse block 2, each value is 8 bits long.
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base = adc1_atten0_Dhigh_word_loc;
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offset = adc1_atten0_Dhigh_offset + Dhigh_data_length * (atten - ADC_ATTEN_DB_0);
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} else {
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// the first value is at the 16th bit of the 5th word of the efuse block 2, each value is 8 bits long.
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base = adc2_atten0_Dhigh_word_loc;
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offset = adc2_atten0_Dhigh_offset + Dhigh_data_length * (atten - ADC_ATTEN_DB_0);
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}
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uint32_t read_result = get_consecutive_bits_from_blk(adc_efuse_block, base, offset, Dhigh_data_length);
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return read_result;
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}
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/* ----------------------- Characterization Functions ----------------------- */
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// coeff_a and coeff_b are actually floats
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// they are scaled to put them into uint32_t so that the headers do not have to be changed
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static const int coeff_a_scaling = 65536;
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static const int coeff_b_scaling = 1024;
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/**
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* The Two Point calibration measures the reading at two specific input voltages, and calculates the (assumed linear) relation
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* between input voltage and ADC response. (Response = A * Vinput + B)
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* A and B are scaled ints.
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* @param high The ADC response at the higher voltage of the corresponding attenuation (600mV, 800mV, 1000mV, 2000mV).
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* @param low The ADC response at the lower voltage of the corresponding attenuation (all 250mV).
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*
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*/
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static void characterize_using_two_point(adc_unit_t adc_num,
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adc_atten_t atten,
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uint32_t high,
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uint32_t low,
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uint32_t *coeff_a,
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uint32_t *coeff_b)
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{
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// once we have recovered the reference high(Dhigh) and low(Dlow) readings, we can calculate a and b from
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// the measured high and low readings
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static const uint32_t v_high[] = {600, 800, 1000, 2000};
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static const uint32_t v_low = 250;
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*coeff_a = coeff_a_scaling * (v_high[atten] - v_low) / (high - low);
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*coeff_b = coeff_b_scaling * (v_low * high - v_high[atten] * low) / (high - low);
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}
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/* ------------------------- Public API ------------------------------------- */
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esp_err_t esp_adc_cal_check_efuse(esp_adc_cal_value_t source)
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{
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if (source != ESP_ADC_CAL_VAL_EFUSE_TP) {
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return ESP_ERR_NOT_SUPPORTED;
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}
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uint8_t adc1_atten0_dh = get_consecutive_bits_from_blk(adc_efuse_block, adc1_atten0_Dhigh_word_loc, adc1_atten0_Dhigh_offset, Dhigh_data_length);
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uint8_t adc2_atten0_dh = get_consecutive_bits_from_blk(adc_efuse_block, adc2_atten0_Dhigh_word_loc, adc2_atten0_Dhigh_offset, Dhigh_data_length);
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if (!adc1_atten0_dh || !adc2_atten0_dh) {
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return ESP_ERR_NOT_SUPPORTED;
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}
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uint8_t adc_encoding_version = get_consecutive_bits_from_blk(adc_calib_ver_block, adc_calib_ver_word_loc, adc_calib_ver_offset, adc_calib_ver_len);
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if (adc_encoding_version != 1) {
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// current version only accepts encoding ver 1.
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return ESP_ERR_INVALID_VERSION;
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}
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return ESP_OK;
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}
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esp_adc_cal_value_t esp_adc_cal_characterize(adc_unit_t adc_num,
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adc_atten_t atten,
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adc_bits_width_t bit_width,
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uint32_t default_vref,
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esp_adc_cal_characteristics_t *chars)
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{
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// Check parameters
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assert((adc_num == ADC_UNIT_1) || (adc_num == ADC_UNIT_2));
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assert(chars != NULL);
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assert(bit_width == ADC_WIDTH_BIT_13);
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// Characterize based on efuse Two Point values. If these values are not present in efuse,
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// or efuse values are of a version that we do not recognize, automatically assume default values.
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uint32_t adc_calib_high, adc_calib_low;
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if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_TP) == ESP_OK) {
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adc_calib_high = read_efuse_tp_high(adc_num, atten);
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adc_calib_low = read_efuse_tp_low(adc_num, atten);
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} else {
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adc_calib_high = 0;
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adc_calib_low = 0;
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}
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uint32_t high = efuse_high_val_to_d(adc_calib_high, adc_num, atten);
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uint32_t low = efuse_low_val_to_d(adc_calib_low, adc_num, atten);
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characterize_using_two_point(adc_num, atten, high, low, &(chars->coeff_a), &(chars->coeff_b));
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// Initialize remaining fields
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chars->adc_num = adc_num;
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chars->atten = atten;
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chars->bit_width = bit_width;
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// these values are not used as the corresponding calibration themes are deprecated.
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chars->vref = 0;
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chars->low_curve = NULL;
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chars->high_curve = NULL;
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// in esp32s2 we only use the two point method to calibrate the adc.
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return ESP_ADC_CAL_VAL_EFUSE_TP;
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}
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uint32_t esp_adc_cal_raw_to_voltage(uint32_t adc_reading, const esp_adc_cal_characteristics_t *chars)
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{
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ADC_CAL_CHECK(chars != NULL, ESP_ERR_INVALID_ARG);
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return adc_reading * chars->coeff_a / coeff_a_scaling + chars->coeff_b / coeff_b_scaling;
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}
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esp_err_t esp_adc_cal_get_voltage(adc_channel_t channel,
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const esp_adc_cal_characteristics_t *chars,
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uint32_t *voltage)
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{
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// Check parameters
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ADC_CAL_CHECK(chars != NULL, ESP_ERR_INVALID_ARG);
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ADC_CAL_CHECK(voltage != NULL, ESP_ERR_INVALID_ARG);
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int adc_reading;
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if (chars->adc_num == ADC_UNIT_1) {
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//Check if channel is valid on ADC1
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ADC_CAL_CHECK((adc1_channel_t)channel < ADC1_CHANNEL_MAX, ESP_ERR_INVALID_ARG);
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adc_reading = adc1_get_raw(channel);
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} else {
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//Check if channel is valid on ADC2
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ADC_CAL_CHECK((adc2_channel_t)channel < ADC2_CHANNEL_MAX, ESP_ERR_INVALID_ARG);
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if (adc2_get_raw(channel, chars->bit_width, &adc_reading) != ESP_OK) {
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return ESP_ERR_TIMEOUT; //Timed out waiting for ADC2
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}
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}
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*voltage = esp_adc_cal_raw_to_voltage((uint32_t)adc_reading, chars);
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return ESP_OK;
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}
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