Noise on Serial

[pschatzmann]

I am trying to read an audio signal that is generated by the ESP32 via Serial using the USB cable of my desktop. To test the functionality I am using a sine wave. The data is written as binary pcm signal (an array of int16_t) with theS help of Serial.write(uint8_t*, size_t len).

#include "AudioTools.h"

AudioInfo info(8000,2,16);                                          // The stream will have 2 channels 
SineWaveGenerator<int16_t> sine(32000);               // subclass of SoundGenerator with max amplitude of 32000
GeneratedSoundStream<int16_t> in_stream(sine);   // Stream generated from sine wave
StreamCopy copier(Serial, in_stream, 32);                // copies 23 bytes of sound to out

void setup(){
  Serial.begin(500000);
  //Serial.setTxBufferSize(1024*2);
  AudioLogger::instance().begin(Serial2, AudioLogger::Warning);  
  sine.begin(info, N_F4);
  in_stream.begin(info);
}
void loop(){
  copier.copy(); 
}

On the desktop I am reading the data with the help of Python pyserial.

It is a kind of half working and I am getting an interleaving clean signal that is followed by noise:

I am currently clueless where this might come from.
Would you have any idea ?

[pschatzmann]

I came to the following conclusion: the issue most likely comes from using the binary data. If just one byte gets lost, the subsequent data can not be read correctly any more...