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CY8CKIT-003 PSoC 3 FirstTouch Starter Kit Guide, Spec. # 001-49613 Rev. *B
Example Projects
4.3
ThermistorTemperatureSense
This project measures the current room temperature and displays it as a rasterized image when the
board is waved.
Running the ThermistorTemperatureSense project:
1. Connect the PSoC 3 FirstTouch Starter Kit board to the USB port of the PC through the USB
cable.
2. Click on the example project ThemistorTemperatureSense from
Kits and Solutions
present on
the Startup page of the PSoC Creator.
3. Make a folder in the desired location and click
OK
.
4. Project opens up in PSoC Creator and gets saved in that folder.
5. Follow step 1 to 4 in section
4.1.3 Build, Program, and Run the PSoC Rocks Project on page 14
to program the project into the PSoC 3 FirstTouch Starter Kit board.
6. When the download is complete, remove the PSoC 3 FirstTouch Starter Kit board from the USB
port and connect a 9V DC battery to the battery connector of the PSoC 3 FirstTouch Starter Kit
board.
7. Hold the board and wave it continuously from left to right as shown in
Figure 3-1 on page 9
. A
rasterized image of the current measured temperature in degree Celsius is visible in the air.
Press the S1 switch and continue to wave the board. The display has switched from Celsius to
Fahrenheit.
4.3.1
How the ThermistorTemperatureSense Project Works
The thermistor example demonstrates how the PSoC device senses temperature using a thermistor.
The thermistor resistance varies with temperature following a predictable nonlinear curve. The
temperature-resistance relationship is given by the Steinhart-Hart equation:
1 /T
k
= A + B*ln(R) + C*(ln(R))
3
In this equation:
■
A, B
, and
C
are empirical constants known as Steinhart-Hart coefficients.
■
R
is the resistance of the thermistor in Ohms.
■
T
k
is the temperature in degree Kelvins.
The same equation, when converted to Celsius scale becomes:
T
c
= T
k
- 273.15
In this equation,
T
c
is the temperature in degree Celsius.
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