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AD9834 Not outputting a waveform properly

Question asked by astro on Oct 12, 2015
Latest reply on Oct 15, 2015 by mcee

Hi,

 

I seem to still be having issues programming my AD9834. The output is usually a dc value (about 300mV, but sometimes, a sine wave with a random amplitude and frequency appears (about 1 in 50 attempts of programming). This would lead me to believe that i am programming something wrong, but the programming bits look correct. (even on an oscilloscope, they look like nice square waves with no significant ringing/overshoot/noise)

 

The circuit is the same as the evaluation board design.

 

I am programming it via SPI with a PIC MCU.

Here is the output of the programming pins:

 

1.jpg

 

 

I am writing the following bits:

   SPIWrite16(0x2100);

   SPIWrite16(0x4651);

   SPIWrite16(0x4D61);

   SPIWrite16(0xC000);

   SPIWrite16(0x2000);

 

 

Thanks!

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