OVMS3-idf/docs/api-reference/peripherals/adc.rst
2017-04-27 19:51:42 +02:00

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Analog to Digital Converter
===========================
Overview
--------
ESP32 integrates two 12-bit SAR ("Successive Approximation Register") ADCs (Analog to Digital Converters) and supports measurements on 18 channels (analog enabled pins). Some of these pins can be used to build a programmable gain amplifier which is used for the measurement of small
analog signals.
The ADC driver API currently only supports ADC1 (9 channels, attached to GPIOs 32-39).
Taking an ADC reading involves configuring the ADC with the desired precision and attentuation settings, and then calling adc1_get_voltage() to read the channel.
It is also possible to read the internal hall effect sensor via ADC1.
Application Example
-------------------
Reading voltage on ADC1 channel 0 (GPIO 36)::
#include <driver/adc.h>
...
adc1_config_width(ADC_WIDTH_12Bit);
adc1_config_channel_atten(ADC1_CHANNEL_0,ADC_ATTEN_0db);
int val = adc1_get_voltage(ADC1_CHANNEL_0);
Reading the internal hall effect sensor::
#include <driver/adc.h>
...
adc1_config_width(ADC_WIDTH_12Bit);
int val = hall_sensor_read();
The value read in both these examples is 12 bits wide (range 0-4095).
API Reference
-------------
Header Files
^^^^^^^^^^^^
* `components/driver/include/driver/adc.h`
Enumerations
^^^^^^^^^^^^
.. doxygenenum:: adc1_channel_t
.. doxygenenum:: adc_atten_t
.. doxygenenum:: adc_bits_width_t
Functions
^^^^^^^^^
.. doxygenfunction:: adc1_config_width
.. doxygenfunction:: adc1_config_channel_atten
.. doxygenfunction:: adc1_get_voltage
.. doxygenfunction:: hall_sensor_read