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PSOC5 audio noize problem | Cypress Semiconductor

PSOC5 audio noize problem

Summary: 2 Replies, Latest post by Bob Marlowe on 02 Oct 2013 04:35 AM PDT
Verified Answers: 0
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maimai's picture
1 post

Hi, My name is imai and developping USB audio playback function with PSOC5-LP.
I am useing USB FS interface and dmac dac8 PGA for analog audio output(PSOC VDD=3.3v)
also using external audio amp.

PSOC5 USB is conneted to PC and I found that USB isocronous transfer contains several digital noize for audio data.

Do someone know that how to reduce usb noize?

I foud that noize as following method
1. transfer isoclonous audio data from PC to PSOC5
2. transfer above data from PSOC5 to PC by Bulk transfer(with error check)
3. compare above 2 datas

Thank ypou

user_119377051's picture
866 posts

 Hi imai, maimai, Interesting!

Would you mind upload your data of these difference.

Of course, isochronous and Bulk has different behavior in case of detail timing but

I am interesting to that may have a noise, how was. 

user_1377889's picture
9300 posts

Just for clarification: There is digital noise when making conversions as ADC or DAC (the latter giving some analog noise) but in a digital data-stream a missed or added bit is not noise, it is simply an ERROR!
Bit-stream errors have a few reasons, mostly

Bad common grounding

Bad (too high) Clock

Same for the data-line

Noisy VCC

All those you can check with a scope.


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