Embedded Real-Time System Programming
Lab Exorcise 2:
1) We now want to exercise the A/D converter with a more typical input device. We will use a thermistor with the NetBurner
to make a thermometer:
Input to A/D converter
Input to I Inp
A) Research thermistors. Describe how they work and explain the relationship between their resistance and their
temperature. Normally thermistors are specified by 1) Nominal Resistance, 2) B Constant, and 3)Temperature
Coefficient. Explain the thermistor temperature vs resistance curve in terms of these parameters.
B) We will be using a Jameco Electronics P/N 207036 thermistor. Go to the Jameco web site and obtain the data sheets
for it. Show the voltage input versus temperature curve you expect to observe.
C) Write a NetBurner program to test your “system.”
D) Construct your thermistor circuit. Use 5 volts for +V (from the NetBurner board – test the voltage using the scope to
make certain you are using the correct power pin – same for gnd) and use a 10K resistor for R.
E) Test your thermister circuit, first without the NetBurner and then with it. Apply several known temperatures to test it
(use a lab thermometer). How do the values compare to those expected?
F) Modify your program to directly read out the temperature of your thermistor circuit.
G) Determine the accuracy of your thermometer.
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