12 Replies Latest reply on Jun 15, 2018 2:30 PM by HaHE_2860291

Dear community,

I have been working with ADC D-S of psoc5lp with no success to amplify 2 diferential signals with 5mVpp as maximum. I have read different documents and I'm very confused about this.

In page 9 of reference document of ADC Delta-Sigma 3.30 the range with Input ± Vref with Vref=1.024V should be: -1.024±1.024= 0V to 2.048. Why in example of CE95271 with the same condition Vref=1.024 on negative pin of ADC, in page 2 says that if positive enter of ADC is 0 the converted value is -1.024 or if is 1.024 the value is 0; so the range doesn't go from 0V to 2.048 as page 9 of ADC Delta-Sigma 3.30 established? then the range to work can support until 2.048 V as a valid value to work???? 2.048 -> 1.024V? Or can I even enter 3V signal with no problem at all? with VDD=5V?

• ###### 1. Re: ADC Delta-Sigma range confusion

Hello Omar

The range can go upto 2.048( 2.044,Vdac max 1.020+1.024). Currently Vdac voltage is 1V. So the maximum value will be 2.024V. The description does not specify about that range. But it is a usable range. Input voltage range is 0-2.024V.

Best Regards,
VSRS

• ###### 2. Re: ADC Delta-Sigma range confusion

Thanks Vsrs,

With 0 at ADC+ conversion will be signed to -0.1024V

with 1.024 at ADC+ conversion will be signed to 0

And here is the confusion: if I enter at ADC+ = 2.048V , Can I expect signed result of +1.024V????? or is this out of range???

What happen if I enter 4V at ADC+ input? ADC conversion value will goes to hexadecimal value of 8000 with 16 bits of resolution?

• ###### 3. Re: ADC Delta-Sigma range confusion

Hi Again Vsrs,

So with differential mode and Vref=1.024V but with ADC- input in 0 the range will be 0±1.024 so-----> -1.024 to 1.024 then:

with ADC+ input in 0 result conversion will be 0?

with ADC+ input in 1.024 result conversion will be 1.024?

Then how to get -.1024 value conversion???? what condition produce this? a negative value????

Thanks.

• ###### 4. Re: ADC Delta-Sigma range confusion
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• ###### 5. Re: ADC Delta-Sigma range confusion

But what happen if Vref=1.024V with ADC- input in 0 the range will be 0±1.024 so-----> -1.024 to 1.024 then:

with ADC+ input in 0 result conversion will be 0?

with ADC+ input in 1.024 result conversion will be 1.024?

Then how to get -.1024 value conversion???? what condition produce this? a negative value????

Thanks.

• ###### 6. Re: ADC Delta-Sigma range confusion

It is better to touch once than see 100 times)))

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• ###### 7. Re: ADC Delta-Sigma range confusion

Thanks Evgeniy, consider this question solved.

• ###### 8. Re: ADC Delta-Sigma range confusion

Hey Evgeniy,

sorry my stupid question, but what is the "RunMean" component in your schematic.

Is this a filter or funktion?

can  you PLEASE  make a short explaination for me as super noob here...

thanks Harry

greetings from Vienna

• ###### 9. Re: ADC Delta-Sigma range confusion

double click on the component:  set Range_of_Filter

Range_of_Filter -determines the buffer size  as a power of 2 (n = 2^Range_of_Filter)

function:

int32 RunMean_Get(int32 Sampl,int32 SIGNAL_SLOPE);

Sampl - new data

SIGNAL_SLOPE - filter re-initialization threshold ( SIGNAL_SLOPE==0 - forced reinitialization )

p.s. I am pleased to remember Vienna - a very beautiful city.

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• ###### 10. Re: ADC Delta-Sigma range confusion

thanks Evgeniy,

I ´m a little bit overcharged .... , but I will go through....

I meant, how you create the component "RunMean", with what kind of component or so...if I want to do so like you?

thanks Harry