esp_adc_cal_characterize() function

Characterize an ADC at a particular attenuation This function will characterize the ADC at a particular attenuation and generate the ADC-Voltage curve in the form of [y = coeff_a * x + coeff_b]. Characterization can be based on Two Point values, eFuse Vref, or default Vref and the calibration values will be prioritized in that order.

Syntax

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Summary

Declaration

Definition

from esp_adc_cal.h:66

esp_adc_cal_value_t 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);

Implemented in esp_adc_cal_legacy.c:280

Arguments

Argument

Declared as

Description

adc_num

adc_unit_t

ADC to characterize (ADC_UNIT_1 or ADC_UNIT_2)

atten

adc_atten_t

Attenuation to characterize

bit_width

adc_bits_width_t

Bit width configuration of ADC

default_vref

uint32_t

Default ADC reference voltage in mV (Only in ESP32, used if eFuse values is not available)

chars

esp_adc_cal_characteristics_t *

Pointer to empty structure used to store ADC characteristics

Return value

- ESP_ADC_CAL_VAL_EFUSE_VREF: eFuse Vref used for characterization - ESP_ADC_CAL_VAL_EFUSE_TP: Two Point value used for characterization (only in Linear Mode) - ESP_ADC_CAL_VAL_DEFAULT_VREF: Default Vref used for characterization

Notes

For ESP32, Two Point values and eFuse Vref calibration can be enabled/disabled using menuconfig. For ESP32s2, only Two Point values calibration and only ADC_WIDTH_BIT_13 is supported. The parameter default_vref is unused.