mirror of
https://github.com/espressif/esp-idf.git
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0c9e2c0fba
This commit removes the lookup table mode due to inferior performance when compared to linear mode under attenuation 0, 1 and 2. However small portions of the lookup table are kept for the higher voltages of atten 3 (above ADC reading 2880). That voltage range in atten 3 has non linear characteristics making the LUT performan better than linear mode.
93 lines
2.9 KiB
C
93 lines
2.9 KiB
C
/* ADC1 Example
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "driver/gpio.h"
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#include "driver/adc.h"
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#include "esp_adc_cal.h"
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#define DEFAULT_VREF 1100 //Use adc2_vref_to_gpio() to obtain a better estimate
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#define NO_OF_SAMPLES 64 //Multisampling
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static esp_adc_cal_characteristics_t *adc_chars;
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static const adc_channel_t channel = ADC_CHANNEL_6; //GPIO34 if ADC1, GPIO14 if ADC2
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static const adc_atten_t atten = ADC_ATTEN_DB_0;
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static const adc_unit_t unit = ADC_UNIT_1;
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static void check_efuse()
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{
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//Check TP is burned into eFuse
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if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_TP) == ESP_OK) {
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printf("eFuse Two Point: Supported\n");
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} else {
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printf("eFuse Two Point: NOT supported\n");
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}
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//Check Vref is burned into eFuse
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if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_VREF) == ESP_OK) {
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printf("eFuse Vref: Supported\n");
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} else {
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printf("eFuse Vref: NOT supported\n");
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}
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}
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static void print_char_val_type(esp_adc_cal_value_t val_type)
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{
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if (val_type == ESP_ADC_CAL_VAL_EFUSE_TP) {
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printf("Characterized using Two Point Value\n");
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} else if (val_type == ESP_ADC_CAL_VAL_EFUSE_VREF) {
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printf("Characterized using eFuse Vref\n");
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} else {
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printf("Characterized using Default Vref\n");
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}
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}
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void app_main()
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{
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//Check if Two Point or Vref are burned into eFuse
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check_efuse();
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//Configure ADC
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if (unit == ADC_UNIT_1) {
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adc1_config_width(ADC_WIDTH_BIT_12);
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adc1_config_channel_atten(channel, atten);
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} else {
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adc2_config_channel_atten((adc2_channel_t)channel, atten);
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}
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//Characterize ADC
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adc_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));
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esp_adc_cal_value_t val_type = esp_adc_cal_characterize(unit, atten, ADC_WIDTH_BIT_12, DEFAULT_VREF, adc_chars);
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print_char_val_type(val_type);
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//Continuously sample ADC1
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while (1) {
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uint32_t adc_reading = 0;
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//Multisampling
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for (int i = 0; i < NO_OF_SAMPLES; i++) {
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if (unit == ADC_UNIT_1) {
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adc_reading += adc1_get_raw((adc1_channel_t)channel);
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} else {
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int raw;
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adc2_get_raw((adc2_channel_t)channel, ADC_WIDTH_BIT_12, &raw);
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adc_reading += raw;
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}
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}
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adc_reading /= NO_OF_SAMPLES;
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//Convert adc_reading to voltage in mV
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uint32_t voltage = esp_adc_cal_raw_to_voltage(adc_reading, adc_chars);
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printf("Raw: %d\tVoltage: %dmV\n", adc_reading, voltage);
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vTaskDelay(pdMS_TO_TICKS(1000));
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}
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}
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