Need help in PSoC ADCINC12 and INSAMP user modules

[Bus Master]

psoc adc

Hi all,

I'm interfacing a thermocouple (type K)to a CY8C26443 chip. Thermocouple to the INSAMP (Ref = AGND) then to the ADCINC12 (REFMUX = 2BG +/- BG). I've applied the (Correlated double Sampling and IIR software filter) to nuteralize the offset voltages and signal noise. The main problem is: i get a correct readings out of the ADC (-800 to +7FF). But, How to accurately convert this value to the corresponding millivolts? I'm a newbie to PSoC programming and i'm really confused. (N.B. REFLO = 1.3V, AGND = 2.6V, REFHI = 3.9V).

Please kindly advise ASAP as i've been stuck at this stupid point for the last 3 days.

Thank you very much for your time.

Yours,

 

[czpir]

insamp psoc

Hi

Here are my thoughts:

Since you are using a 12 bit ADC and assuming your swing is -5 0 +5 then

-5 volts = 0 ADC counts
0 volts = 2048 ADC counts
+5 volts = 4095 ADC counts

Then for the ADC count you have sampled

v = (5 * (x - 2048)) / (4096 - 2048)