PT8211 Audio Kit Playback Distortion

Status
Not open for further replies.

jdev

Member
I've recently assembled the PT8211 audio kit (thanks PJRC for developing this great kit!).

However I'm testing the playback in comparison to the SGTL5000 and I'm getting some very noticeable distortion with the PT8211 kit.

Has anyone else experienced this issue?

I'm using the test sine code from https://github.com/PaulStoffregen/A...les/HardwareTesting/PT8211Sine/PT8211Sine.ino
Code:
#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// GUItool: begin automatically generated code
AudioSynthWaveform       waveform1;      //xy=110,75
AudioOutputPT8211        pt8211_1;          //xy=303,78
AudioConnection          patchCord1(waveform1, 0, pt8211_1, 0);
AudioConnection          patchCord2(waveform1, 0, pt8211_1, 1);
// GUItool: end automatically generated code

void setup() {
  AudioMemory(15);
  waveform1.begin(WAVEFORM_SINE);
  waveform1.frequency(440);
  waveform1.amplitude(0.99);
}

void loop() {
}

Here's the oscilloscope reading with jagged sine waves (in light blue):
FullSizeRender(1).jpg
 
Last edited:
I tested a PT8211 board just now. Here it is on my desk:

DSC_0593_web.jpg

Here's the waveform I see on my scope when running the code you posted:

file.png

Here's another view with the scope's FFT turned on. Looks like minor harmonics at 880, 1320, 2200 and 3080, but they're all at -50dB or less.

file.png

I have no idea why your PT8211 board is making that terrible waveform. The sine output looks pretty good here.
 
Status
Not open for further replies.
Back
Top