Trouble with Noise/ wrong configuration?

Hi, 

 I'm working on LCDK6748 with TIRTOS v. 2.0.1.23 , XDC 3.30.3.47 and CCS v6.0.1.00040. Codec is AIC3106 and DSP is OMAPL138. I wrote a simple program to perform Audio Echo chanel sample by sample.  I'm generating sine wave with 400Hz and amplitude 390mV. My code alows me to acquire sine wave :   

,but returned signal  is heavily distorted :  

I have no idea what is the issue of this distortion. Is anybody have any clue what am I doing wrong? Below  I attach file with my init codes for McAsp, codec and with main(). 

Thanks,

Best Regards

Mirek  

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