In the RTD example project provided in PSoC Creator 2.1,what is the significance of using the temperature scale in 'main.c'?
A PT100 has a temp range of -200°C to +850°C which is superiour to any semi-conductor sensor. Together with the calibration to get rid of the non-linearities a max precision of 0.01°C within an interval can be archieved.
Have a look into the component's datasheet, under the header "General" you'll find a short description what the component is and what it is good for.
At first I thought it was to get to volts as the RTD is 100 ohms. Eg. its actually
a scale factor for the RTD not being 1 ohm. But I am not sure. Contact the
author of the ap note, and re-post here the answer.
Praveen Sekar [firstname.lastname@example.org]
There are 2 projects with AN70698. 1. RTD temperature measurement, 2. Broken RTD reconfiguration
Which line of code in main.c are you referring to?
I can't speak for original poster but in PSOC 3 RTD Example project in
Creator, line 28, there is a define -
#define TEMP_SCALE (100u)
and used line 140 -
rtdTempDisp = (float) rtdTemp / TEMP_SCALE ;
Where did you download the RTD example project from?
In Creator, an example project, 5.1
The RTD temperature measurement project.Lines 28,29 and 140 in main.c
The RTD_GetTemperature() API takes resistance in milliohms as argument and returns temperature in 1/100th of a degree celcius.
The temperature scale and resistance scale aid in converting temperature in 1/100th of a degree celcius to degree celcius and resistance in milliohms to resistance in ohms respectively