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AD9833 Frequency Register Update

Question asked by OWeber on Nov 7, 2012
Latest reply on Nov 8, 2012 by OWeber

Hello,

 

we are working with AD9833 and it is running fine. What we have problems to understand is, that when we update the frequency register with 28 Bit new value as 2 16Bit dataword writes, the output of the AD9833 changes frequency to very high value after the first data word (14 LSB´s) write to FREQ0 is finshed. After second dataword is written, the frequency at output is correct again. During write of the 2 data words the FSYNC stays low.

B28 is set in the control register.

 

Question: Do we always need to write first the control register and then the 28 Bit frequency value or is it enough to write once the contorl register and after that just update the frequency register ?

 

Currently the update of the frequency register gives short high frequency output from first word ( 14 Bit LSB´s ) finished writing to second word (14 Bit MSB´s ) finshed writing.

 

Regards, Ottmar

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