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AD2S1205 - Why does it count up to 4095 two times in every period?

Question asked by ap_nick on May 14, 2015
Latest reply on Jun 22, 2015 by jcolao

Hi,

 

I am facing a very strange problem:

 

I am using AD2S1205 to get the position on my DSP through serial interface.

However, the position data I am getting vary from 0 to 4095 (12bits), BUT 2 times in every resolver full electric cycle.

I am checking with the Osciloscope the sinusoidal output of the resolver and I get zero position every time the sin amplitude is zero (not every 2 times that would make one full rotation)

 

I am attaching an explanatory picture of what I have. The green  numbers is what I get for position.

problem.jpg

 

The even stranger thing is that when I checked the NM pulses of the incremental encoder output, it only had 1 pulse per revolution.

It makes no sense! Encoder output seems correct, but the serial interface output is wrong.

 

Do you have any idea on what could cause that?

 

I am using PWMSYNC as the SAMPLE input. Could that cause the problem?

 

Thank you for your help!

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