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Thermistors: Using the supplied spreadsheets

In January 2012 we introduced the Thermistor has command, which effectively makes the use of spreadsheets unnecessary. SPLat/PC can now do all the hard work for you.

To help you work out what you need to achieve temperature measurements with a SPLat and a thermistor, we have produced a couple of spreadsheet called thrmstr8.xls and ThermstrNorm.xls. These spreadsheets are used for determining the parameters, component values and the polynomial equation that converts raw readings into degrees. The files are installed along with SPLat/PC in the folder C:\Program Files\SPLat\SPLATPC\examples\thermistor. If you don't have the files you can find them online in the File Resources part of our website.

The main difference between the two spreadsheet files is that ThermstrNorm.xls is more recent version that uses normalized analog input readings from the fAnIN instruction. If you are using a board earlier than dialect 18, you need the other, older thrmstr8.xls version. This tutorial was however written around thrmstr8.xls, which assumes the old integer analog input instructions.

To get the most out of this tutorial please locate thrmstr8.xls and launch it now (you will need Excel 97 or a later version). You may be asked to enable macros. Without macros enabled the spreadsheet won't work.

Hint: It is an very good idea to make a copy of the spreadsheet, and work on that. Keep a copy of the original in a safe place. Working with the spreadsheet will modify it, so it's good to have an easy way to get back to the original.

Many of the spreadsheet cells have descriptive comments. Roll your mouse over the cells with small red triangles to see the comments

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In This Chapter

Thermistors: Introduction to spreadsheet

Thermistors: Setting the temperature range

Thermistors: Specifying the thermistor

Thermistors: Selecting miscellaneous parameters

Thermistors: Selecting drive voltage and resistance

Thermistors: Fine tuning

Thermistors: Evaluating the results

Thermistors: Extracting polynomial coefficients

Thermistors: Generating the SPLat code

Thermistors: A worked example