esp-idf/docs/en/api-reference/peripherals/dac.rst
2020-02-07 16:37:44 +11:00

47 lines
1.6 KiB
ReStructuredText

Digital To Analog Converter
===========================
{IDF_TARGET_DAC_CH_1: default = "GPIO25", esp32 = "GPIO25", esp32s2 = "GPIO17"}
{IDF_TARGET_DAC_CH_2: default = "GPIO26", esp32 = "GPIO26", esp32s2 = "GPIO18"}
Overview
--------
{IDF_TARGET_NAME} has two 8-bit DAC (digital to analog converter) channels, connected to {IDF_TARGET_DAC_CH_1} (Channel 1) and {IDF_TARGET_DAC_CH_2} (Channel 2).
The DAC driver allows these channels to be set to arbitrary voltages.
The DAC channels can also be driven with DMA-style written sample data, via the :doc:`I2S driver <i2s>` when using the "built-in DAC mode".
For other analog output options, see the :doc:`Sigma-delta Modulation module <sigmadelta>` and the :doc:`LED Control module <ledc>`. Both these modules produce high frequency PWM output, which can be hardware low-pass filtered in order to generate a lower frequency analog output.
Application Example
-------------------
Setting DAC channel 1 ({IDF_TARGET_DAC_CH_1}) voltage to approx 0.78 of VDD_A voltage (VDD * 200 / 255). For VDD_A 3.3V, this is 2.59V::
#include <driver/dac.h>
...
dac_output_enable(DAC_CHANNEL_1);
dac_output_voltage(DAC_CHANNEL_1, 200);
API Reference
-------------
.. include-build-file:: inc/dac.inc
GPIO Lookup Macros
^^^^^^^^^^^^^^^^^^
Some useful macros can be used to specified the GPIO number of a DAC channel, or vice versa.
e.g.
1. ``DAC_CHANNEL_1_GPIO_NUM`` is the GPIO number of channel 1 ({IDF_TARGET_DAC_CH_1});
2. ``DAC_{IDF_TARGET_DAC_CH_2}_CHANNEL`` is the channel number of GPIO 26 (channel 2).
.. include-build-file:: inc/dac_channel.inc