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What is the fastest way to change freq. & off freq.(in AD9910)

Question asked by JongWon on Feb 4, 2013
Latest reply on Feb 5, 2013 by KennyG

Hello. I'm using AD9910.

My routine is,

 

(1) Initializing Register & setting Amplitude by serial pins.

(2) Setting freq. by parallel pins.

 

Setting freq. routine is following,

 

   TxEN = 1;     //Enable TxENABLE pin High

   F1 = 1;          //

   F0 = 0;          //F1 & F0 is parallel port destination pins

   P1 = 0x12;     //

   P0 = 0x34;     //P1 & P0 is GPIO in CPU, & it is connected to D0~D15 directly.

   TxEN = 0;     //TxENABLE pin Low

 

by that code, I can set freq. I think setting freq. is fast enough.

Now I want to DDS output off the fastest way.

Please give me some advice.

 

================

following is my thinking. but my poor english skill, you may have problem to understand it. So just view references.

 

(1) Use profile.

I think, If I put Amplitude 0, freq. 0hz data to single tone profile, then If I select that profile,

DDS output may 0.

But, to use this way, Some Registers should be changed.(parallel mode -> single tone mode)

 

(2)

   TxEN = 1;     //Enable TxENABLE pin High

   F1 = 0;          //

   F0 = 0;          //F1 & F0 is parallel port destination pins

   P1 = any value;     //

   P0 = any value;     //P1 & P0 is GPIO in CPU, & it is connected to D0~D15 directly.

   TxEN = 0;     //TxENABLE pin Low

(Since AD9910 parallel mode doesn't have memory) After setting freq., If I change F1 & F0, then output may go to zero.

But I can not sure this way is good.

 

(3) Use only single tone profile.

First, put data single tone profile0.

Next, put zero data(Amp. 0, freq. 0 hz) to single tone profile1

If I only change profile0 to 1, or 1 to 0,

I can set freq. and off freq.

 

===========

Please give me some advice and recommend the fastest way.

 

Thank you.

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