Contents
1
2
Quickstart ..................................................................................................................................4
Introduction ...............................................................................................................................6
2.1
Sensor Types ................................................................................................................................. 6
Uncompensated - constant voltage operation ..................................................................... 6
Uncompensated - constant current operation ..................................................................... 7
Signal-conditioned - Digital/I2C ............................................................................................ 7
Signal-conditioned - Amplified analog .................................................................................. 7
2.1.1
2.1.2
2.1.3
2.1.4
3
Calibration .................................................................................................................................7
3.1
3.2
Why do we need a calibration? .................................................................................................... 7
Theory of Calibration .................................................................................................................. 10
Compensation approaches for uncompensated pressure sensors .................................... 10
Constant voltage mode ....................................................................................................... 11
Constant current mode ....................................................................................................... 16
3.2.1
3.2.2
3.2.3
4
Using the Evaluation Kit ............................................................................................................ 19
4.1
Setup ........................................................................................................................................... 19
Range setup of compensated sensors ................................................................................ 22
4.1.1
4.2
4.3
Measurement pages ................................................................................................................... 23
How to do a calibration............................................................................................................... 25
Constant voltage calibration ............................................................................................... 26
Constant current calibration ............................................................................................... 29
4.3.1
4.3.2
4.4
5
Troubleshooting .......................................................................................................................... 30
Evaluation Kit Hardware ........................................................................................................... 31
5.1
5.2
Hardware Design Explained ........................................................................................................ 31
Circuitry ....................................................................................................................................... 32
Amplification Circuit............................................................................................................ 32
Optional Level Shift ............................................................................................................. 33
Power Supply ...................................................................................................................... 34
Temperature Measurement ............................................................................................... 34
5.2.1
5.2.2
5.2.3
5.2.4
5.3
6
7
Uncompensated constant current sensor board ........................................................................ 35
Expected Performance .............................................................................................................. 36
Appendix .................................................................................................................................. 39
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
8
Detailed PCB Schematics............................................................................................................. 39
PCB Layout .................................................................................................................................. 40
Used Hardware Elements/BOM .................................................................................................. 40
Power supply schematic ............................................................................................................. 44
Jumper Settings........................................................................................................................... 44
Flowchart LabVIEW Software ..................................................................................................... 45
Flowchart Microcontroller Software........................................................................................... 46
Microcontroller Command Set ................................................................................................... 46
Revision History........................................................................................................................ 47
1 Quickstart
Step 0:
Before you start, make sure that all compatible drivers are installed on your PC.
In order to run the
Evaluation
Kit
software,
the
LabVIEW
2012
Runtime
Engine
(dir\Contents\07_Driver_and_Runtime_Engine\LVRTE2012f3std.exe) and the NI VISA Runtime 5.4
(dir\Contents\07_Driver_and_Runtime_Engine\visa540_runtime.exe) have to be installed. The driver for
the RS232 adaptor is also provided in the same folder on the USB drive, but may install automatically
when you plug the adaptor into your PC for the first time.
Step 1:
Connect the Evaluation Kit base board to the power supply and to the PC through the included RS232
adaptor (see Figure 1). To enable a connection with the PC, it is necessary to know to which COM port
the Evaluation Board is connected. The assigned COM port is indicated in the device manager of the
operating system.
The Evaluation kit base board and the sensor board have to be connected as shown in Figure 1 or with
the provided extension cable.
Figure 1: Fully assembled and connected Evaluation Kit
Step 2:
Run the Evaluation Kit Software executable (see Figure 2), which is provided on the USB-Stick that is part
of the Evaluation Kit (dir\Contents\06_LabVIEW_Exe\Hybrid Evaluation Kit v3.exe).
Figure 2: Main page of the Evaluation Kit software
Step 3:
Choose the part number according to the sensor that is connected to the Evaluation Board (see
1
in
Figure 2).
Change the COM port to the one that has been assigned to the Evaluation Board (see
2
in Figure 2).The
correct COM port number can be found in the operating system’s device manager under “Ports (COM &
LPT).
Make sure that the supply voltages on the board set by hardware jumper SV1 (see appendix, section 7.5
for more info) and in the software (see
3
in Figure 2) match and are suitable for the used sensor.
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