CY8CKIT-003A Cypress Semiconductor Corp, CY8CKIT-003A Datasheet - Page 23

• Manufacturer Part Number: CY8CKIT-003A
• Description: KIT DEV PSOC3 FIRSTTOUCH STARTER
• Manufacturer: Cypress Semiconductor Corp
• Series: PSoC® 3 FirstTouch™r
• Type: MCUr

Specifications of CY8CKIT-003A

• Contents: Board, Battery, Cable, CD, Documentation, Wire
• Lead Free Status / Rohs Status: Lead free by exemption / RoHS compliant by exemption
• For Use With/related Products: PSoC® 3
• Other names: 428-3113

4.3.1.1
CY8CKIT-003 PSoC 3 FirstTouch Starter Kit Guide, Spec. # 001-49613 Rev. *B
Figure 4-12. Temperature Sensor Project Flowchart
Temperature Sensing Design Principle
As shown in
resistor on one side and the thermistor on the other to estimate the thermistor resistance. The
temperature calculations are as accurate as the resistance measurement of the thermistor.
Figure 4-13. Temperature Sensing Design Principle
This setup significantly removes gain and offset errors from the resistance calculation.
The analog voltage output from the divider is converted to a digital signal using the ADC on the
PSoC. To gain additional accuracy, the voltage at the input side of the divider is also measured. The
resistor value is calculated using the ratio of the voltages across the two resistors in the resistor
ladder.
In this equation, V
Offset errors, if any, are removed due to subtraction of the two measured voltages. The ratio of these
two values removes the measurement path gain error. The error due to the reference resistor is
reduced by using a precision resistance in series with the thermistor.
R
Thermistor
R
Ref
Compute temperature
Change temperature
If switch is pressed?
V
2
display mode
V
V
0
1
Yes
Start
M
Boot
A
U
X
Figure
Yes
VDC
Blocks
2
= 0 (Ground voltage)
ADC
4-13, the design for temperature sensing uses a voltage divider with a precision
PSoC
No
Rthermistor = Rref * (V
Calculate character offset
Update the raster display
in the string and update
accelerometer Y axis
Read and process
String complete?
LED display
data array
voltage
1
-V
No
2
/V
0
-V
1
)
Example Projects
23