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esp_adc_cal/Remove lookup table

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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.
This commit is contained in:
Darian Leung
2018-02-13 20:47:18 +08:00
parent 73cdfbfe79
commit 0c9e2c0fba
9 changed files with 381 additions and 647 deletions
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126
examples/peripherals/adc/main/adc1_example_main.c
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@@ -14,67 +14,79 @@
#include "driver/adc.h"
#include "esp_adc_cal.h"
#define PRINT_VAL_SUPPORT(support, type) ({ \
if(support == ESP_OK){ \
printf("%s: supported\n", (type)); \
} else { \
printf("%s: not supported\n", (type)); \
} \
})
#define PRINT_VAL_TYPE(type, mode) ({ \
if(type == ESP_ADC_CAL_VAL_EFUSE_TP){ \
printf("%s mode: Two Point Value\n", (mode)); \
} else if (type == ESP_ADC_CAL_VAL_EFUSE_VREF){ \
printf("%s mode: eFuse Vref\n", (mode)); \
} else { \
printf("%s mode: Default Vref\n", (mode)); \
} \
})
#define DEFAULT_VREF 1100 //Use adc2_vref_to_gpio() to obtain a better estimate
#define NO_OF_SAMPLES 64
#define NO_OF_SAMPLES 64 //Multisampling
static esp_adc_cal_characteristics_t *adc_linear_chars;
static esp_adc_cal_characteristics_t *adc_lut_chars;
static adc1_channel_t channel = ADC1_CHANNEL_6;
static esp_adc_cal_characteristics_t *adc_chars;
static const adc_channel_t channel = ADC_CHANNEL_6; //GPIO34 if ADC1, GPIO14 if ADC2
static const adc_atten_t atten = ADC_ATTEN_DB_0;
static const adc_unit_t unit = ADC_UNIT_1;
void app_main(void)
static void check_efuse()
{
//Check if Two Point or Vref are burned into eFuse
esp_err_t efuse_vref_support = esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_VREF);
esp_err_t efuse_tp_support = esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_TP);
PRINT_VAL_SUPPORT(efuse_vref_support, "eFuse Vref");
PRINT_VAL_SUPPORT(efuse_tp_support, "eFuse Two Point");
//Configure ADC1
adc1_config_width(ADC_WIDTH_BIT_12);
adc1_config_channel_atten(channel, ADC_ATTEN_DB_0);
//Characterize ADC1 in both linear and lut mode
adc_linear_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));
adc_lut_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));
esp_adc_cal_value_t lin_val_type = esp_adc_cal_characterize(ADC_UNIT_1, ADC_ATTEN_DB_0, ESP_ADC_CAL_MODE_LIN, DEFAULT_VREF, adc_linear_chars);
esp_adc_cal_value_t lut_val_type = esp_adc_cal_characterize(ADC_UNIT_1, ADC_ATTEN_DB_0, ESP_ADC_CAL_MODE_LUT, DEFAULT_VREF, adc_lut_chars);
PRINT_VAL_TYPE(lin_val_type, "Linear");
PRINT_VAL_TYPE(lut_val_type, "LUT");
//Continuously sample ADC1
while(1){
uint32_t adc1_raw = 0;
//Multisample
for(int i = 0; i < NO_OF_SAMPLES; i++){
adc1_raw += adc1_get_raw(channel);
}
adc1_raw /= NO_OF_SAMPLES;
uint32_t corrected_linear = esp_adc_cal_raw_to_voltage(adc1_raw, ADC_WIDTH_BIT_12, adc_linear_chars);
uint32_t corrected_lut = esp_adc_cal_raw_to_voltage(adc1_raw, ADC_WIDTH_BIT_12, adc_lut_chars);
printf("Raw: %d\tLinear: %dmV\tLUT: %dmV\n", adc1_raw, corrected_linear, corrected_lut);
vTaskDelay(pdMS_TO_TICKS(1000));
//Check TP is burned into eFuse
if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_TP) == ESP_OK) {
printf("eFuse Two Point: Supported\n");
} else {
printf("eFuse Two Point: NOT supported\n");
}
//Check Vref is burned into eFuse
if (esp_adc_cal_check_efuse(ESP_ADC_CAL_VAL_EFUSE_VREF) == ESP_OK) {
printf("eFuse Vref: Supported\n");
} else {
printf("eFuse Vref: NOT supported\n");
}
}
static void print_char_val_type(esp_adc_cal_value_t val_type)
{
if (val_type == ESP_ADC_CAL_VAL_EFUSE_TP) {
printf("Characterized using Two Point Value\n");
} else if (val_type == ESP_ADC_CAL_VAL_EFUSE_VREF) {
printf("Characterized using eFuse Vref\n");
} else {
printf("Characterized using Default Vref\n");
}
}
void app_main()
{
//Check if Two Point or Vref are burned into eFuse
check_efuse();
//Configure ADC
if (unit == ADC_UNIT_1) {
adc1_config_width(ADC_WIDTH_BIT_12);
adc1_config_channel_atten(channel, atten);
} else {
adc2_config_channel_atten((adc2_channel_t)channel, atten);
}
//Characterize ADC
adc_chars = calloc(1, sizeof(esp_adc_cal_characteristics_t));
esp_adc_cal_value_t val_type = esp_adc_cal_characterize(unit, atten, ADC_WIDTH_BIT_12, DEFAULT_VREF, adc_chars);
print_char_val_type(val_type);
//Continuously sample ADC1
while (1) {
uint32_t adc_reading = 0;
//Multisampling
for (int i = 0; i < NO_OF_SAMPLES; i++) {
if (unit == ADC_UNIT_1) {
adc_reading += adc1_get_raw((adc1_channel_t)channel);
} else {
int raw;
adc2_get_raw((adc2_channel_t)channel, ADC_WIDTH_BIT_12, &raw);
adc_reading += raw;
}
}
adc_reading /= NO_OF_SAMPLES;
//Convert adc_reading to voltage in mV
uint32_t voltage = esp_adc_cal_raw_to_voltage(adc_reading, adc_chars);
printf("Raw: %d\tVoltage: %dmV\n", adc_reading, voltage);
vTaskDelay(pdMS_TO_TICKS(1000));
}
}