ESP32 and I2S passthru reader/writer problem

[thaaraak]

I have been playing around with the streams-i2s-i2s.ino example. I am using an ESP32 and the pMod I2S2 board and share the MCLK, BCLK and WS lines between the input and output (data input and output are separate of course)

I am feeding the input with a simple sine wave from a signal generator I have noticed some instabilities with the output - particularly on a warm boot. Essentially the output audio is garbage - which only returns to normal after I remove power to both ESP32 and the pMod board. Not sure what is causing this but seems as if input/output isn't synchronized perhaps?

Based on what I have seen with the I2S streams in the ESP-ADF toolkit I decided to change the underlying code to have the I2S input and output streams share the same i2s port. This does mean:

• You have to change the begin code to call i2s_driver_install only once
• You have to pass the tx and rx pin numbers into i2s_set_pin
• You have to set the i2s_config mode to be master | RX | TX

My suspicion is using the same i2s port, because its the same interrupt removes the synchronization problem. Anyway - I have included my hacked code.

i2s.zip

[thaaraak]

Forgot to add the calling code...

 // start I2S in
  Serial.println("starting I2S...");
  auto config_in = in.defaultConfig(RX_MODE);
  config_in.sample_rate = sample_rate;
  config_in.bits_per_sample = 16;
  config_in.i2s_format = I2S_STD_FORMAT;
  config_in.is_master = true;
  config_in.port_no = 0;
  config_in.pin_ws = 18;
  config_in.pin_bck = 5;
  config_in.pin_data = 17;
  config_in.pin_mck = 0;

  config_in.use_apll = true;

  in.beginit(config_in, 19, 17, true );

  // start I2S out
  auto config_out = out.defaultConfig(TX_MODE);
  config_out.sample_rate = sample_rate;
  config_out.bits_per_sample = 16;
  config_out.i2s_format = I2S_STD_FORMAT;
  config_out.is_master = true;
  config_out.port_no = 0;
  config_out.pin_ws = 18;
  config_out.pin_bck = 5;
  config_out.pin_data = 19;
  config_out.pin_mck = 0;

  config_out.use_apll = true;

  out.beginit(config_out, 19, 17, false );

[pschatzmann]

The code above is correct for the setup with 2 ports. If you want to use one port only it will need to be something like this:

Serial.println("starting I2S...");
auto config = in.defaultConfig(RXTX_MODE);
config.sample_rate = sample_rate;
config.bits_per_sample = 16;
config.i2s_format = I2S_STD_FORMAT;
config.is_master = true;
config.port_no = 0;
config.pin_ws = 18;
config.pin_bck = 5;
config.pin_data = 19;
config.pin_data_in = 17;
config.pin_mck = 0;

I have this kind of logic working for the LyraT and AudioKit support with the AudioKitStream. Unfortunately it is not available yet for pure I2S, but I can try to commit a correction tomorrow....

e

[thaaraak]

Thank you I'll try your code out.

[pschatzmann]

I have committed the related changes to I2SConfig.h and I2SESP32.h. I hope I did not forget anything...

[pschatzmann]

ps. here is an audiokit example that uses the same stream to do input and output. With the latest changes the same should work with I2SStream..

[thaaraak]

Ah - so just use the same I2S Stream instance for input and output to the Copier. Thank you - I will give it a try ASAP

[thaaraak]

I think you missed a "return"

/home/xenir/Arduino/libraries/arduino-audio-tools/src/AudioTools/Resample.h:395:52: warning: no return statement in function returning non-void [-Wreturn-type]
         int available() override { up.available(); }

[pschatzmann]

Thanks...corrected

[thaaraak]

Worked like a charm!! Although I am still getting a compile error in line 395 of Resample.h

Thank you - off to try the FIR filters now!

[pschatzmann]

Strange. I just doule checked on github: line 395 is

    int available() override { return up.available(); }

On 14 Feb 2022, at 20:39, thaaraak @.***> wrote:

Worked like a charm!! Although I am still getting a compile error in line 395 of Resample.h

Thank you - off to try the FIR filters now!

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[thaaraak]

never mind - problem my end - all good now