ESP32 PDM Microphone (SPM0405HD4H) and built-in DAC/PDM output Example
This is based on ESP-IDF i2s_adc_dac Example. Adapted to PlatformIO IDE for VSCode
Please refer to https://kunsen.net/ for details.
- This is an example of:
- Recording sound from PDM Microphone (SPM0405HD4H)
- Replay the recorded sound via PDM or DAC
- Play an audio file in flash
- Run this example
- Set partition table to "partitions_adc_dac_example.csv" in platformio.ini
- This example will execute the following steps:
- Erase flash
- Record audio from PDM microphone and save in flash
- Read flash and replay the sound via PDM or DAC
- Play an example audio file(file format: 8bit/8khz/single channel)
- Loop back to step 3
- Hardware connection: Please refer to https://kunsen.net
How to generate audio files:
- tools/generate_audio_file.py is an example of generate audio table from .wav files.
- In this example, the wav file must be in 16k/16bit mono format.
- generate_audio_file.py will bundle the wav files into a single table named audio_example_file.h
- Since the ADC can only play 8-bit data, the script will scale each 16-bit value to a 8-bit value.
- Since the ADC can only output positive value, the script will turn a signed value into an unsigned value.
- DAC can only play 8-bit data, so the wav file data are scaled to 8-bit data.
- I2S DMA can only output 16-bit/32-bit data to DAC, DAC will only take the highest 8-bit data and output accordingly.
- Before I2S DMA can output data stream to DAC, the data format should be converted to 16-bit or 32-bit by padding zeros.