scaling to physical value in FPGA

[gary36]

I am using a 12 bit ADC in my board. I need to convert this value to physical value (ie.. 0-10V) .
I tried multiplying ADC input with 10000. But I am not sure how many bits to shift. If I fix 14 bits (corresponding to 10000) Iam getting wrong answer

 

[KlausST]

Hi


I´m confused...

if you want to convert a digital value (12 bit) into a physical value(0..10V) then you need a DAC. (no ADC)
Maybe additionally an OPAMP to adjust output voltage range.

ADC input is analog. Did you use OPAMP with gain of 10000? But what´s the input of the OPAMP?
The ouput of an ADC is digital. If 12 bit then 0...4095.

Shift by 14 bits to left means multiplying by 16384, not 10000.

What does "getting wrong answer" mean?

Klaus

 

[gary36]

sorry, I did not spell out that scaling needs to be done within FPGA so that the equvalent physical value can be displayed in LED 7 segments. I was facing issue with Q format multiplication and now it is clear. Anyways thank you. It is resolved

 

[KlausST]

Hi,

something like this is what usually I expect from the OP:

Please correct/complete this:
analog value (range...) --> OPAMP (gain, offset) --> ADC (resolution, range) --> mathematical calculation(variable type, range, resolution...) -->
--> transforming for dispalying (variable count, variable type, range) --> display (digit count, how many fractional digits)...

If necessary for your question: display type: like multiplexing, interface....

Klaus

 

[FvM]

Multiply with 10000, shift right by 12 (cut 12 lower bits) scales the ADC value to 0...10000.