36 lines
1.5 KiB
Markdown
36 lines
1.5 KiB
Markdown
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# Digital output via I2S to a external DAC
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Somtimes we want to store the sound file in memory. [Audacity](https://www.audacityteam.org/) might help you out here: export with the file name audio.raw as RAW signed 16 bit PCM and copy it to the SD card. In the example I was just using one channel to save memory!.
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Then you can convert the file with xxd into a C file that contains the data in an array. In the Sketch I am using the __MemoryStream class__ which turns the array into a Stream.
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Please note that you must compile this sketch with the __Partition Scheme: Huge App__!
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### External DAC:
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For my tests I am using the 24-bit PCM5102 PCM5102A Stereo DAC Digital-to-analog Converter PLL Voice Module pHAT
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I am just using the default pins defined by the framework. However I could change them with the help of the config object. The mute pin can be defined in the constructor of the I2SStream - by not defining anything we use the default which is GPIO23
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DAC | ESP32
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-----|----------------
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VCC | 5V
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GND | GND
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BCK | BCK (GPIO14)
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DIN | OUT (GPIO22)
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LCK | BCK (GPIO15)
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FMT | GND
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XMT | 3V (or another GPIO PIN which is set to high)
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- DMP - De-emphasis control for 44.1kHz sampling rate(1): Off (Low) / On (High)
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- FLT - Filter select : Normal latency (Low) / Low latency (High)
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- SCL - System clock input (probably SCL on your board).
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- FMT - Audio format selection : I2S (Low) / Left justified (High)
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- XMT - Soft mute control(1): Soft mute (Low) / soft un-mute (High)
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