Cao Sen Miao
88 lines
2.8 KiB
ReStructuredText
88 lines
2.8 KiB
ReStructuredText
Digital To Analog Converter (DAC)
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=================================
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{IDF_TARGET_DAC_CH_1: default = "GPIO25", esp32 = "GPIO25", esp32s2 = "GPIO17"}
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{IDF_TARGET_DAC_CH_2: default = "GPIO26", esp32 = "GPIO26", esp32s2 = "GPIO18"}
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Overview
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--------
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{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).
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The DAC driver allows these channels to be set to arbitrary voltages.
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.. only:: esp32
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The DAC channels can also be driven with DMA-style written sample data by the digital controller, via the :doc:`I2S driver <i2s>` when using the "built-in DAC mode".
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.. only:: esp32s2
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The DAC channels can also be driven with DMA-style written sample data by the digital controller, please check the Application Example(DMA part) to get more information.
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For other analog output options, see the :doc:`Sigma-delta Modulation module <sdm>` and the :doc:`LED Control module <ledc>`. Both these modules produce high frequency PDM/PWM output, which can be hardware low-pass filtered in order to generate a lower frequency analog output.
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Application Example
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-------------------
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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.
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.. code:: c
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#include <driver/dac.h>
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...
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dac_output_enable(DAC_CHANNEL_1);
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dac_output_voltage(DAC_CHANNEL_1, 200);
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.. only:: esp32s2
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For {IDF_TARGET_NAME}, DAC support to use DMA to send digital data to convert. Here is the example:
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.. code-block:: c
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#include <driver/dac.h>
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const dac_digi_config_t cfg = {
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.mode = mode,
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.interval = 100,
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.dig_clk.use_apll = false, // APB clk
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.dig_clk.div_num = 79, // See comments `adc_digi_clk_t`
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.dig_clk.div_b = 1,
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.dig_clk.div_a = 0,
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.dac_dma_cnt = 1, // The dac dma link number for your project
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.dac_dma_length = 512, // The dac dam link length for your project. Should fit the buffer you prepared with dac_dma_cnt.
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.dac_dma_link_type = DAC_DMA_LINK_RECURSIVE, //The link type.
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};
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dac_digi_initialize(&cfg);
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dac_output_enable(DAC_CHANNEL_X);
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dac_digi_start();
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dac_digi_write_bytes((uint8_t*)buffer_you_prepared);
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dac_digi_stop();
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dac_digi_deinitialize();
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API Reference
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-------------
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.. include-build-file:: inc/dac.inc
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.. include-build-file:: inc/dac_common.inc
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GPIO Lookup Macros
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^^^^^^^^^^^^^^^^^^
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Some useful macros can be used to specified the GPIO number of a DAC channel, or vice versa.
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e.g.
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1. ``DAC_CHANNEL_1_GPIO_NUM`` is the GPIO number of channel 1 ({IDF_TARGET_DAC_CH_1});
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2. ``DAC_{IDF_TARGET_DAC_CH_2}_CHANNEL`` is the channel number of GPIO 26 (channel 2).
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.. include-build-file:: inc/dac_channel.inc
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.. include-build-file:: inc/dac_types.inc
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