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PSoC™ 5, 3 & 1 Forum Discussions

Anonymous
Not applicable

Hi,

   

I plan to build an LVDT Signal conditioner lik This in Datasheet of AD630 page 17 , but with source of 13 kHz

   

 

   

( Using Wave-Dac-Sinus from PSoC + extern THS4531A) but I don´t use Hw-Phase Shifter ) Is it possible to obtain from Wave-Dac

   

rectangle (log. signal) with phase shift 90 degree?

   

How can I to use with input -Mi- of SigmaDelta ADC v3.2 ?

   

I should obtain a synchro-demodulated signal ..

   

regards

   

zbyno

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1 Solution
EvPa_264126
Level 7
Level 7
500 replies posted 250 replies posted 100 likes received


You want the sine frequency 13 kHz.
You should know that the DAC has a maximum sampling frequency of 1 MHz and 8-bit resolution.
It seems table-DMA-DAC is the only way to create multiple signals at this frequency.
But! You will encounter the problem of synchronization of separate DMA channels.
It has a little here: Terminating DMA
If you have an oscilloscope - you can experiment with the attached project.
But it seems some phase shifters on the opamps - the best solution.

View solution in original post

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6 Replies
Anonymous
Not applicable

Picture of LVDT

   

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Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

And what is your question?

   

 

   

Bob

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Anonymous
Not applicable

My question is:

   

Why can I accurately synchronize of measure cycle of DeltaSigma conversion with sine-wave from Waveform DAC ?

   

They both should be the very same..

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EvPa_264126
Level 7
Level 7
500 replies posted 250 replies posted 100 likes received


You want the sine frequency 13 kHz.
You should know that the DAC has a maximum sampling frequency of 1 MHz and 8-bit resolution.
It seems table-DMA-DAC is the only way to create multiple signals at this frequency.
But! You will encounter the problem of synchronization of separate DMA channels.
It has a little here: Terminating DMA
If you have an oscilloscope - you can experiment with the attached project.
But it seems some phase shifters on the opamps - the best solution.

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Anonymous
Not applicable

Thank you Pavloven,

   

I will experiment with your file...

   

I have additionally 1 question - the SigmaDelta-conversion time has to be accurately equal to period of sine (about 13kHz)

   

 1.what means this term actual conv.rate?

   

Where can I find appl. note about this conversion / with number of clock cycles?

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EvPa_264126
Level 7
Level 7
500 replies posted 250 replies posted 100 likes received


It is difficult to understand the problem without seeing the project ...
inductive sensor signal can be obtained as follows:
PGA-> mixer (synchronous detector) -> RC filter -> PGA -> ADC
Phase synchronous detector has an offset to a small (adjustable) angle.
Commonly used phase shifter at the Shelter.
Yes, the ADC conversion, it is desirable to synchronize with a base frequency (Hardware SOC).
conversion rate - the maximum.