AD9833 output issue


I tried to follow App Note 1070 to create 400 MHz sin wave for AD9833 chip. The only different is my MCLK is 16 MHz so the FREQ0 calculation is 0x1A37 for my case.

Here is the sequence on the SPI bus (waveform attached, too):

  1. 0x2100
  2. 0x5a37
  3. 0x4000
  4. 0xC000
  5. 0x2000

I did see the sin waveform but the problem is it's not 400 Hz but 200 KHz. I don't know what I did wrong? Any idea?

For the SPI bus, the SCLK is 6 MHz while MCLK is 16 MHz. Does it matter?

I use SPI MODE 0 (POL = 0, PHA = 0): active high, data sampling on rising edge of SCLK.

I use ARM A8 processor.

Any help is appreciated. Thanks.


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