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Problem of the ADSP21369 acquisition signal

Question asked by apple_srf on Jan 1, 2018
Latest reply on Jan 15, 2018 by Jithul_Janardhanan

Hello Engineers,

     I modify the routines provided (see attachment).My purpose is to obtain sinusoidal signals collected. I use  the ADSP21369 Ezkit(When debugging the Block-based Talkthrough program in the ADSP21369 Ezkit Demo
). The ADC (LEFT and RIGHT) connection signal generator——Frequency is 40Hz and Amplifier is 100mv and offset is 0. When I run the program, it can be seen in the diagram that the sine signal is inverted 180 degrees(Fig 1). This is Why? Changing frequency to 400Hz still has the same situation(Fig 2).The NUM_SAMPLES is 1024 in program(And ADCFS48).Why do I have this problem, can give answers.
      I'll put the program in the attachment. Please check it.
                                                                             (Fig 1)
 
                                                                         (Fig 2)
why?

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