ADAU1702 EQ Frequency offset?

When I add an EQ setting  in the SigmaStudio, but the EQ of the curve scan by the AP is  different  from which I set in the SigmaStudio.

The EQ frequency offset.

For example,when I set an 100HZ high pass filter in the SigmaStudio, but the frequency of high pass filter is about 300HZ in the  curve scan by the AP.The Sampling rate is right.

attachments.zip
  • 0
    •  Super User 
    on Jun 29, 2013 7:59 AM

         Hello Wade,

         As it turns out, your ADAU1702 is running at 88.2 KHz even though the design is at 44.1.  The chip's rate is controlled by the "program length" control in the 170x / 140x Register Control window, as shown here:

         "2x" means the core is running twice as fast as normal, with only half the instruction capacity.  Because this drop-down box is the same for the ADAU1701 and -1702, the number of instructions the box shows is misleading. To run at 44.1 KHz you'll need to set this box to 1x (1024 instructions), even though the -1702 only has room for 512 instructions.  You'll also need to use a 11.2896 MHz crystal; the usual 12.288 MHz one would have you running at 48 KHz.

         For more info, see this FAQ:  http://ez.analog.com/docs/DOC-1431

         Best regards,

         Bob

  • Hello Robert,

    Thank you for you patience reply, my problem has resolved.

    I set the sampling rate wrong.

    The 0x081C register's bit0 and bit1 use to set sample rate.