CY8CKIT-025 PSoC® Precision Analog Temperature Sensor Expansion Board Kit Guide, Doc. # 001-65791 Rev. *J
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Example Projects
Note:
In the firmware, voltage displayed on the LCD for the 5-V rail is truncated to two digits after
the decimal point. Therefore, when the potentiometer is turned to the
0V
position, if the ADC
result is negative due to negative offset error, you will see ‘–0.00’ on the LCD. Increase the num-
ber of digits after the decimal point to be displayed on the LCD by increasing the floating point
qualifier in the line number 105 of the
display.c
file.
5.3.2.2.2
CY8CKIT-001 PSoC DVK
The steps to run the example firmware on CY8CKIT-001 are:
1. Apply 12 VDC power to the PSoC DVK.
2. Attach the MiniProg3 device, first to a USB port on the PC and then to the PROG port on the
CY8CKIT-009 PSoC 3/CY8CKIT-010 PSoC 5LP processor module.
3. Open the SequenceADC_001 project using PSoC Creator and select
Debug > Program
to pro-
gram the PSoC.
4. Disconnect power to the PSoC DVK and connect hardware according to
.
5. Power the PSoC DVK.
6. On reset, the LCD displays a welcome message and then the RTD temperature, which is the first
item in the user selectable menu.
7. Press CapSense button
P0_5
to scroll up the menu and
P0_6
to scroll down the menu.
Note
: The diode temperature in CY8CKIT-001 is slightly lower than the actual temperature. This is
because CY8CKIT-001 is a general-purpose board and is not optimized for analog routing.
5.3.2.3
Testing the Project
For best results when testing the temperature measurements, ensure that you have good thermal
contact between the sensor (RTD, diode, or IC sensor) and your reference thermometer.
5.3.2.4
Expected Performance and Test Results
This section provides details about the expected performance of the temperature, voltage, and
power rail measurements. The output expected from the temperature sensors are similar to those
described in the previous example project, except for minor differences, such as use of 16-bit ADC
for all measurements. It is recommended to see
Expected Performance and Test Results on page 36
before reading this section. The focus of this example is to show multiplexing multiple input sources,
that is, voltages, temperatures, and power rails. The section
details the tolerance specification of each temperature sensor and the expected
temperature performance from the sensors.
Following are typical expected results for each measurement observed on a sample board.
5.3.2.4.1
Voltage (20 mV) Input
A voltage source is used to provide inputs from –20 mV to +20 mV and the output displayed by
PSoC is compared to a multimeter output.
The 20 mV reading should typically be within ± 40 µV of the actual value. The ADC gain error is the
main factor driving this error and the PSoC 3 ADC with a maximum gain error of 0.2% keeps the
measurement inaccuracy to < 40 µV.
5.3.2.4.2
100 mV Input
A voltage source is used to provide inputs from –100 mV to +100 mV and the output displayed by
PSoC is compared to a multimeter output.
