Hello,
I am using the CN-0326 Evaluation Kit (pH and Temperature Measurement) and I am trying to make it work on my own microcontroller without the given Software. My Problem is the Temperature, I am using a PT1000 with two wires. The Problem is: the Resistance I measure is always a bit higher than it should be. For example if i pug in a 984Ohm Resistance, my Code tells me it is 1000Ohm (always about 10-20Ohms higher). Is there any way to fix/compensate it, or is it a known error? Since in the configuration in the given Software CN0326 you have to set the RTD(0°) Value. I already had to set the RTD0 value to 1014 there to get good results.
this is the part of the code if someone sees any mistakes:
unsigned long tcode = AD7793_ContinuousReadAvg(10); //code: digitales temperatursignal avg
double tavin = (((double) tcode / (8388608)) - 1) * Vref; //umrechnung von digitalem signal in Volt
double r = tavin / (Vref/5000); //umrechnung in Wiederstand r
double tempWert = ((r / RTD) - 1.0) / 0.00385; //umrechnung in °C
Vref is being measurent(about 1.017 and RTD is set to 1014
Thank you for your help,
Best regards, Marc