CY8CKIT-025 PSoC® Precision Analog Temperature Sensor Expansion Board Kit Guide, Doc. # 001-65791 Rev. *J
50
Example Projects
Note
: The calibration constant is used inside diode temperature measurement function for calibra-
tion. On system reset, the calibration constant is initialized as ‘1’. After calibration, the constants are
stored in EEPROM. These values can be used for power-on-reset calibration. This can be imple-
mented by users and is not demonstrated in this project.
5.2.3.3.7
IC Calibration
DS600 IC is used for cold junction compensation. Ideally an isothermal connection should be pro-
vided between the cold junction sensor and cold junction terminals. If that is not possible, having the
cold junction sensor very close to the cold junction terminals is sufficient as it is done on CY8CKIT-
025. This may result in a small temperature offset of around 0.5 °C. For high accuracy, a calibration
routine, which performs a single point calibration, is provided to calibrate the temperature offset
between the cold junction and the IC thermal pads.
The calibration steps for the IC temperature measurement are as follows:
1. Scroll down to the
Calibrate IC
(eleventh) item in the menu using CapSense buttons.
2. Proceed through the calibration steps using mechanical switch SW2 connected to P6[1] of
CY8CKIT-030 or SW1 connected to P1[7] of CY8CKIT-001.
3. The LCD displays "Set Temp:".
Force the IC temperature to a known measured value between 0 °C and 100 °C and enter that
temperature using the CapSense slider and buttons. Use the CapSense slider for coarse temper-
ature setting and the CapSense button for fine settings (P5_5/P0_5 to increment the temperature
in 0.1 °C steps and P5_6/P0_6 to decrement the temperature in 0.1 °C). After the temperature is
entered accurately, press the mechanical button
SW2
(CY8CKIT-030) or
SW1
(CY8CKIT-001) to
calibrate.
4. The IC calibration constant (Offset) is calculated as the difference in measured temperature and
the expected temperature value entered by the user. After calibration, the LCD displays the mes-
sage "Calibrated". Press
SW2
(CY8CKIT-030) or
SW1
(CY8CKIT-001) to go back to main menu.
Figure 5-14. IC Calibration
Enter IC Cal
Set calibration
temperature (tCal)
Measure IC
temperature (tMeas)
IC offset = tMeas - tCal
Save the calibration
constant in EEPROM
Enter calibration
temperature using
CapSense button and
slider
Go back to the main
menu on next switch
press
