ESP32 WROOM32E with DAC PCM1754

[cocowayco]

Hi,
I have found this code here on Github in order to reproduce bluetooth music, and I modified it to add a PLL out, but I can get it to work.
I have an external DAC (PCM1754) attached to the ESP32 Wroom32E via I2S.
Since the DAC needs a masterclock to work (unlike the PCM5102 for example, which generates the MCK within itself), I am using GPIO0 to output a PLL of 11.2896MHz.
The DAC is silent, no output.
WS, DATA, BCK are fine.
GPIO0 is a strange quasi SINE of 11.2896MHz (I was expecting a square wave)

Can anyone help

Has anybody done this already?

Thanks

#include "AudioTools.h"
#include "BluetoothA2DPSink.h"

I2SStream i2s;
BluetoothA2DPSink a2dp_sink(i2s);

void setup() {
auto cfg = i2s.defaultConfig();

cfg.sample_rate = 44100; // Match Bluetooth A2DP capability
cfg.bits_per_sample = 16; // ESP32 cannot send 24-bit over A2DP
cfg.channels = 2;
cfg.i2s_format = I2S_MSB_FORMAT; // PCM1754 requires MSB

cfg.pin_mck = 0;
cfg.pin_bck = 23;
cfg.pin_ws = 21;
cfg.pin_data = 22;

cfg.buffer_size = 128; // Optimize for stability
cfg.buffer_count = 8;

i2s.begin(cfg);

a2dp_sink.start("MyMusic");
}

void loop() {
}

[pschatzmann]

For testing the output please follow the instructions from the AudioTools under the heading Audio Sink!

You need to read the technical sheet of your DAC. Keep in mind that

• not all DACs support 16 bit (some need 24 or 32 bits)
• not all DACs support the default masterclock multiple of 256, so you might need to change this parameter
• you might need to unmute your DAC (via a pin or hardware)

[pschatzmann]

See this example.
Here is the documentation

[pschatzmann]

Did you finally get the PCM1754 working ?

[cocowayco]

ok, so I followed your instructions and your code (thank you very very much by the way), and I have got it to work.
The fact is that I don't understand why. I need to clarify the situation because it is messy, and I don't like messy.
So basically this is the code with the conversion:

#include "AudioTools.h"
#include "BluetoothA2DPSink.h"

AudioInfo info(44100, 2, 32);
I2SStream out;
NumberFormatConverterStream convert(out);
BluetoothA2DPSink a2dp_sink(convert);

void setup() {
Serial.begin(115200);
// AudioToolsLogger.begin(Serial, AudioLogger::Info);

// Configure i2s to use 32 bits
auto cfg = out.defaultConfig();
cfg.copyFrom(info);

cfg.i2s_format = I2S_MSB_FORMAT; // PCM1754 requires MSB
cfg.pin_mck = 0;
cfg.pin_bck = 23;
cfg.pin_ws = 21;
cfg.pin_data = 22;

out.begin(cfg);

// Convert from 16 to 32 bits
convert.begin(16, 32);

// start a2dp
a2dp_sink.start("AudioKit");
}

void loop() {
delay(1000); // do nothing
}

Since the IC is in I2S mode MSB it needs 48 or 64fs ( as you noticed). That would translate in a sampling frequency of 44100kHz (unchanged) and a bit rate of 48, making the BCK 4.233MHz.
Instead as you can see I have 44100KHz (WS), 2.82MHz (BCK) and 11.2896 masterclock.
Also you said that: "48 times the sampling frequency of BCK is limited to 192/384/768 fS SCK". How did you obtain this info?

[pschatzmann]

I was copying this from the PCM1754 data sheet.
You can try with some other cfg.mclk_multiple values

[cocowayco]

Yes, but why not 256fs?