PT8211 and Teensy 4

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My next question was who is their official reseller for ordering genuine PT8211 parts. Answer:
You can contact our distributor in Europe. Below is the contact information.

Olga Prediger
Line Manager
Eurocoin GmbH • Lorenz-Huber-Strasse 13 • 85540 Haar • Germany
Phone: +49 89 46 23 07 14 • Fax: +49 89 46 23 07 99
E-Mail: olga.prediger@eurocoincomponents.com

Best regards

Paul
 
Thank you Paul,

I have ordered the original PT8211-S from PTC but the delivery time is long
so I will continue to test my card meanwhile:
1. Check with a sinus-wave to rule out my raw-input.
2. Test to put an op-amp between the chip and output.
3. Test with T3.2 instead of T4

/Tomas
 
Saw that too... I guess these photo's were made when Paul prototyped the first PT8211 kits and ordered parts from Ebay.
The PJRC kits I have here contain the genuine PT8211-S part, see my photo in message #21.

Paul
 
Until now, I was unaware there were different PT8211 chips (other than S suffix means SOIC package).

I believe PJRC has purchased 3 different batches of PT8211 chips, so the parts we're shipping are likely a mix of whatever came in those 3 orders. I can tell you I have personally soldered at least 1 chip from each batch and listened to it play as a quick check each batch was good. Those tests were done with the PT8211 output connected to a M-Audio AV40 monitor speaker with fairly casual listening.
 
I have run tests with the example: PT8211Sine code

It produces almost no distortion which is good. Maybe my chip is Ok after all

#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
AudioSynthWaveform waveform2; //xy=110,75
AudioOutputPT8211 pt8211_1; //xy=303,78

AudioMixer4 mix1;
AudioMixer4 mix2;

AudioConnection c1(waveform1, 0, mix1, 0);
AudioConnection c2(waveform2, 0, mix2, 0);
AudioConnection c3(waveform1, 0, pt8211_1, 0); // right channel
AudioConnection c4(waveform2, 0, pt8211_1, 1); // left channel
// GUItool: end automatically generated code

void setup() {
AudioMemory(15);

mix1.gain(0,0.9);
mix2.gain(0,0.9);

waveform1.begin(WAVEFORM_SINE);
waveform1.frequency(44);
waveform1.amplitude(0.0001);

waveform2.begin(WAVEFORM_SINE);
waveform2.frequency(440);
waveform2.amplitude(0.2);
}

void loop() {
}

I'm seeing left channel = c4
In this case it works OK (see Sine 1)

(The right channel also works as expected)

But if I change connection c3 to:

AudioConnection c3(mix1, 0, pt8211_1, 0); // right channel

I get a distortion on the left channel = Sine 2
(and the right channel is silent)

If I change to left also (both channels through mixers)

AudioConnection c4(mix2, 0, pt8211_1,1); // left channel

Everything works OK again.


If I do the same in my earlier Flash_pt_test example the code hangs instead and the Left channel is silent.

Something must be wrong in the code for the PT8211 output running on Teensy 4.0

/Tomas
 

Attachments

  • Sine 1.jpg
    Sine 1.jpg
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  • Sine 2.jpg
    Sine 2.jpg
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Check also what happens when you leave one input (left or right) unconnected.
For me that hangs the code.

/Tomas
 

Attachments

  • output_pt8211.cpp
    18.1 KB · Views: 73
Thank you Paul!
My problems are gone. The last of my distortion vanished when I out commented the right channel:

// output t0 PT8211 dac (both L och R)
//AudioConnection c20(mix1, 0, ptout, 0);
AudioConnection c21(mix1, 0, ptout, 1);

I'm not sure why that is. The channels seems to interact with eachother. Maybe another bug?

I will still make a PC-board with the T3.2 instead of T4 to test if there is a difference.

However, this means that my chip PT8211-H from Ebay is OK
and I can start selling my Kets Midibass

/Tomas
 

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  • Ketsmidibass1.jpg
    Ketsmidibass1.jpg
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I'm glad that fixed the problem!


The channels seems to interact with eachother. Maybe another bug?

Maybe. Very difficult to say. There is quite a lot of complex code doing the 4X oversampling.

As always, it takes test case like you posted in msg #32 for any sort of serious investigation to happen.


and I can start selling my Kets Midibass

Let me know when the product is shipping. Maybe we can show it on the blog, hopefully bringing you a few more sales.
 
Thank you, I will
I love your Teensys

If I have had more skills developing drivers in C++ I would have helped out.

/Tomas
 
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