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Altera_Forum
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16 years ago

Noise on DE2 Board (audio issue)

Hi, from some time i have big problem with noise, I have altera de2 board (NOT 70), I clock XCK clock using 18432000 Khz clock from PLL (actualy 18421053). Everything is good, but i've got noise on about 6 bits, i feed signal from board to AMP and noise is amplificated which is bad for me :) ... Anyway, i looked at ADCDAT compared to ADCLRCK pin on logic analyser and osciloscope, noise is on ADCDAT line.I connected audio in to LEDs for positive part of signal and 5 and half of leds is blinking always. Even when i short circuit both channels of MIC or line in to ground. I thought that it is becouse of 10khz difference betwen proper XCK and these which i feed to it. But it can't be changed, oh and i got information in warnings about : 

 
altpll:altpll_component|pll" output port clk feeds output pin "AUD_XCK" via
non-dedicated routing -- jitter performance depends on switching rate of other design elements. 
Use PLL dedicated clock outputs to ensure jitter performance

But i don't have any idea how to connect these clocks via proper way... Maybe it is the couse of noise ?

My I2C is configured that way : 

when inLeft     => daneDoWyslania <= X"3400" & "000" & volIn; 
        when inRight    => daneDoWyslania <= X"3402" & "000" & volIn; 
        when outLeft    => daneDoWyslania <= X"3404" & "0" & volOut; 
        when outRight    => daneDoWyslania <= X"3404" & "0" & volOut; 
        when analog  => daneDoWyslania <= X"340815"; 
        when digital    => daneDoWyslania <= X"340A06"; 
        when power    => daneDoWyslania <= X"340C00"; 
        when format     => daneDoWyslania <= X"340E01"; 
        when sampling    => daneDoWyslania <= X"341002"; 
        when on    => daneDoWyslania <= X"341201";

--EDIT

I attach screen of logic analyser , upper signal is ADCLRCK, 1 is left chan, 0 is right chan, 48Khz sampling, lower is ADCDAT line ....

http://dark.art.pl/~kvasir/noise.jpg

--EDIT2

Aha .... Strange behaviour ... When i stuck my board(plexiglass cover) with finger led's are blinking and from AMP i hear this stucking ... Board works like MICrophone, even when nothing is connected to input of codec ... is it normal ? For me very strange ...

Any help is appreciated, thank you and i'm waiting for replies...