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Not able to write the CTW0 in AD9959

Question asked by Rice on Mar 30, 2011
Latest reply on Mar 31, 2011 by Rice

Hello,

 

I am trying to drive the AD9959 with a custom program in a microcontroller. Up to know, I get to communicate with the DDS and store new data in the registers. I follow the communication protocoll as it is detailled in the datasheet and I have annalysed how the evaluation software generates the data streams in order to have a practical feedback.

 

The problem is that when I give the IO_UPDATE signal... the output does not change. I have been reading all the registers I previously saved and I get all the correct information back, but the CTW0, which remains at 00000000h though I have it configured at a certain frequence.

 

What can be happening here?

 

Also, I see that the evaluation software reads the register 19h right at the start of operation... what is this?

 

Thank you very much in advance.

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