54 lines
1.7 KiB
Markdown
54 lines
1.7 KiB
Markdown
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# I2S built-in ADC/DAC Example
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---
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* This is an example of:
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* Recording sound from ADC
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* Replay the recorded sound via DAC
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* Play an audio file in flash
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---
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* Run this example
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* Set partition table to "partitions_adc_dac_example.csv" in menuconfig, or rename sdkconfig.default to sdkconfig directly.
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* Set IDF_PATH and run "make flash"
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---
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* This example will execute the following steps:
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1. Erase flash
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2. Record audio from ADC and save in flash
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3. Read flash and replay the sound via DAC
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4. Play an example audio file(file format: 8bit/8khz/single channel)
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5. Loop back to step 3
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---
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* Hardware connection:
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| ESP32 | Microphone + amplifier | amplifier + speaker |
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|--|--|--|
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| GPIO36(ADC1CH0 input) | data output pin | |
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| GPIO25(DAC1 output) | | right channel speaker input|
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| GPIO26(DAC2 output) | | left channel speaker input|
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---
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* How to generate audio files:
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* tools/generate_audio_file.py is an example of generate audio table from .wav files.
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* In this example, the wav file must be in 16k/16bit mono format.
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* generate_audio_file.py will bundle the wav files into a single table named audio_example_file.h
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* Since the ADC can only play 8-bit data, the script will scale each 16-bit value to a 8-bit value.
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* Since the ADC can only output positive value, the script will turn a signed value into an unsigned value.
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---
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* Note:
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* DAC can only play 8-bit data, so the wav file data are scaled to 8-bit data.
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* I2S DMA can only output 16-bit/32-bit data to DAC, DAC will only take the highest 8-bit data and output accordingly.
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* Before I2S DMA can output data stream to DAC, the data format should be converted to 16-bit or 32-bit by padding zeros.
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