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why temperature scale?
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why temperature scale?

poorva12 posted on 17 Jan 2013 8:27 AM PST
Senior Member
19 Forum Posts

In the RTD example project provided in PSoC Creator 2.1,what is the significance of using the temperature scale in 'main.c'?




Re: why temperature scale?

Bob Marlowe posted on 17 Jan 2013 09:17 AM PST
Top Contributor
1768 Forum Posts

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.

 

Happy coding

Bob



Re: why temperature scale?

danaaknight posted on 17 Jan 2013 12:29 PM PST
Top Contributor
1773 Forum Posts

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 [pfz@cysemi.com]

 

Regards, Dana.



Re: why temperature scale?

pfz posted on 17 Jan 2013 09:22 PM PST
Cypress Employee
19 Forum Posts

Poorva,

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? 

Regards,

Praveen

 

 



Re: why temperature scale?

danaaknight posted on 18 Jan 2013 02:20 AM PST
Top Contributor
1773 Forum Posts

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 ;

 

Regards, Dana.

 



Re: why temperature scale?

pfz posted on 18 Jan 2013 04:19 AM PST
Cypress Employee
19 Forum Posts

 Hi Dana,

Where did you download the RTD example project from?

Regards,

Praveen

 



Re: why temperature scale?

danaaknight posted on 18 Jan 2013 04:36 AM PST
Top Contributor
1773 Forum Posts

In Creator, an example project, 5.1

 

Regards, Dana.



Re: why temperature scale?

poorva12 posted on 19 Jan 2013 04:31 AM PST
Senior Member
19 Forum Posts

Praveen Sir,

The RTD temperature measurement project.Lines 28,29 and 140 in main.c



Re: why temperature scale?

pfz posted on 21 Jan 2013 10:09 PM PST
Cypress Employee
19 Forum Posts

 Poorva/Dana,

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

Regards,

Praveen

 

 

 

 

 






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