96 lines
3 KiB
ReStructuredText
96 lines
3 KiB
ReStructuredText
I2S
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===
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Overview
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--------
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ESP32 contains two I2S peripherals. These peripherals can be configured to input and output sample data via the I2S driver.
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The I2S peripheral supports DMA meaning it can stream sample data without requiring each sample to be read or written by the CPU.
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I2S output can also be routed directly to the Digital/Analog Converter output channels (GPIO 25 & GPIO 26) to produce analog output directly, rather than via an external I2S codec.
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.. note:: For high accuracy clock applications, APLL clock source can be used with `.use_apll = 1` and ESP32 will automatic caculate APLL parameter.
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Application Example
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-------------------
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A full I2S example is available in esp-idf: :example:`peripherals/i2s`.
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Short example of I2S configuration:
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.. highlight:: c
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::
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#include "driver/i2s.h"
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#include "freertos/queue.h"
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static const int i2s_num = 0; // i2s port number
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static const i2s_config_t i2s_config = {
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.mode = I2S_MODE_MASTER | I2S_MODE_TX,
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.sample_rate = 44100,
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.bits_per_sample = 16,
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.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
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.communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
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.intr_alloc_flags = 0, // default interrupt priority
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.dma_buf_count = 8,
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.dma_buf_len = 64,
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.use_apll = 0
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};
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static const i2s_pin_config_t pin_config = {
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.bck_io_num = 26,
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.ws_io_num = 25,
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.data_out_num = 22,
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.data_in_num = I2S_PIN_NO_CHANGE
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};
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...
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i2s_driver_install(i2s_num, &i2s_config, 0, NULL); //install and start i2s driver
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i2s_set_pin(i2s_num, &pin_config);
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i2s_set_sample_rates(i2s_num, 22050); //set sample rates
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i2s_driver_uninstall(i2s_num); //stop & destroy i2s driver
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Short example configuring I2S to use internal DAC for analog output::
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#include "driver/i2s.h"
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#include "freertos/queue.h"
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static const int i2s_num = 0; // i2s port number
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static const i2s_config_t i2s_config = {
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.mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN,
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.sample_rate = 44100,
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.bits_per_sample = 16, /* the DAC module will only take the 8bits from MSB */
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.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
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.communication_format = I2S_COMM_FORMAT_I2S_MSB,
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.intr_alloc_flags = 0, // default interrupt priority
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.dma_buf_count = 8,
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.dma_buf_len = 64,
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.use_apll = 0
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};
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...
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i2s_driver_install(i2s_num, &i2s_config, 0, NULL); //install and start i2s driver
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i2s_set_pin(i2s_num, NULL); //for internal DAC, this will enable both of the internal channels
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//You can call i2s_set_dac_mode to set built-in DAC output mode.
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//i2s_set_dac_mode(I2S_DAC_CHANNEL_BOTH_EN);
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i2s_set_sample_rates(i2s_num, 22050); //set sample rates
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i2s_driver_uninstall(i2s_num); //stop & destroy i2s driver
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API Reference
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-------------
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.. include:: /_build/inc/i2s.inc
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