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4.3 Capturing the ADC Signals

To capture the ADC signal, go to the "ADC Capture" tab and click the "Capture" button. If you are using and
AudioWell DN-25 meter, you should see a signal that looks like 

Figure 4-6

 at zero flow.

Figure 4-6. Captured ADC Signal

If the capture looks different, check these items first.

• Reduce the gain in your configuration parameters to –6.5 dB. Because the captured signal is windowed, the

tail of the signal may be slightly truncated without changing the results.

• Adjust the Gap between pulse start and ADC capture. 

Figure 4-7

 shows an example where the gap is set too

long. 

Figure 4-8

 shows an example where the gap is set too short.

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USS GUI

SLAU810B – SEPTEMBER 2019 – REVISED SEPTEMBER 2020

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Water Flow Meter

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Содержание MSP430FR6047

Страница 1: ... Waveforms 14 4 5 Frequency Response 15 5 Meter Characterization 16 5 1 Single Shot Standard Deviation 16 5 2 Zero Flow Drift Testing 16 5 3 Flow Testing 17 6 Revision History 18 List of Figures Figure 2 1 EVM430 FR6047 Connected to Flow Meter 3 Figure 2 2 EVM430 FR6047 Jumper Settings 3 Figure 3 1 Select MSP430FR6047 Device 4 Figure 3 2 Load Image 4 Figure 4 1 USS GUI Connected to EVM 5 Figure 4 ...

Страница 2: ...Ultrasonic Sensing Solution USS Library and interfaces to the GUI http software dl ti com msp430 msp430_public_sw mcu msp430 USSSWLib USSSWLibWater latest index_FDS html 4 The USS library and supporting documentation of the APIs that are available in the library http software dl ti com msp430 msp430_public_sw mcu msp430 USSSWLib USSSWLibWater latest index_FDS html 1 2 What is Not Included An Audio...

Страница 3: ...he J5 header are required for communication with the GUI TEST and RST jumpers on J2 are required to program the board The POW_SEL switch should be in the middle position ezFET J1 in the right position and both J3 jumpers set to use USB power The jumper locations are highlighted in Figure 2 2 Figure 2 2 EVM430 FR6047 Jumper Settings 3 Make sure that there is water in the flow meter www ti com Conne...

Страница 4: ... the EVM 1 Install the Uniflash tool on your PC 2 Install the latest water metering firmware which can be downloaded from http software dl ti com msp430 msp430_public_sw mcu msp430 USSSWLib USSSWLibWater latest index_FDS html 3 Open Uniflash and select the MSP430FR6047 device Figure 3 1 Select MSP430FR6047 Device 4 Choose Connection 5 Choose image to load Default image is installed in C ti msp Ult...

Страница 5: ...GUI Connect to the platform by clicking Connect in the Communications menu The GUI reports the connection as shown in Figure 4 1 Figure 4 1 USS GUI Connected to EVM www ti com USS GUI SLAU810B SEPTEMBER 2019 REVISED SEPTEMBER 2020 Submit Document Feedback Water Flow Meter 5 Copyright 2020 Texas Instruments Incorporated ...

Страница 6: ...on the anticipated ultrasonic time of flight for a given flow tube with enough additional capture time to address signal shifts due to temperature variations The GUI Based Gain Control controls the gain of the integrated PGA Set this parameter to give an ADC capture of no more than 900 ADC counts in the ADC capture tab Although the system should be operable with signals down to 150 ADC counts sett...

Страница 7: ...uld be used as a starting point The UPS0 to UPS1 Gap is the time between the end of a set of measurements and the beginning of the next set of measurements Power consumption is directly affected by the measurement rate A UPS0 to UPS1 gap of 1 second consumes roughly twice as much power as a UPS0 to UPS1 gap of 2 seconds The default setting for this parameter should be used as a starting point Set ...

Страница 8: ...o the absolute ToF to account for any additional delays The value depends on the shape of the signal and the envelope threshold Developers can optionally set this value to zero and make their own adjustments of the absolute ToF in the application layer Increase the Capture Duration for configurations with a larger number of pulses or decrease it for configurations with smaller number of pulses to ...

Страница 9: ...ot currently used by the Lobe algorithm User Param 6 is reserved for future use User Param 10 is reserved for future use 4 2 3 Conditional Parameters Modify the following parameters only under specific conditions The ULP Bias Delay determines when the bias circuit is turned on The relevant timing diagrams for the operation of the ULP bias circuit can be found in the MSP430FR58xx MSP430FR59xx and M...

Страница 10: ...stal or resonator settling Based on internal experiments 120 µs is suggested for resonators and 5000 µs is suggested for crystals The Search Range parameter is specific to gas algorithms and is not currently used by the Lobe algorithm 4 2 4 Configuration Tuning After a working configuration has been set you can experiment with changes to that working set to tune the system for optimum performance ...

Страница 11: ...t Reduce the gain in your configuration parameters to 6 5 dB Because the captured signal is windowed the tail of the signal may be slightly truncated without changing the results Adjust the Gap between pulse start and ADC capture Figure 4 7 shows an example where the gap is set too long Figure 4 8 shows an example where the gap is set too short www ti com USS GUI SLAU810B SEPTEMBER 2019 REVISED SE...

Страница 12: ... Capture Set Too Long Figure 4 8 Gap Between Pulse Start and ADC Capture Set Too Short USS GUI www ti com 12 Water Flow Meter SLAU810B SEPTEMBER 2019 REVISED SEPTEMBER 2020 Submit Document Feedback Copyright 2020 Texas Instruments Incorporated ...

Страница 13: ...he EVM the captured signal may look similar to Figure 4 9 Figure 4 9 Captured ADC Signal With No Water or Bad Connection To save the capture click the Save Capture button and provide a filename To continuously capture to a file click the Continuous Capture button and provide a filename www ti com USS GUI SLAU810B SEPTEMBER 2019 REVISED SEPTEMBER 2020 Submit Document Feedback Water Flow Meter 13 Co...

Страница 14: ...alue of Delta ToF can be seen in the red box shown in Figure 4 10 Figure 4 10 Capturing Waveforms The frequency of measurement updates can be increased by reducing the UPS0 to UPS1 Gap in the Configuration tab After capturing waveforms for some time you can save them to a file using the Save Waveforms button The Lock All button stops updates and the Reset Graphs button erases all previously captur...

Страница 15: ...e can be summarized as follows Note Steps 1 to 3 should have already been completed in Section 4 3 1 Set the Transmit Frequency to the nominal frequency of the transducer 2 Adjust the Gap between pulse start and ADC capture and Capture Duration parameters to capture the complete signal in the ADC Capture window 3 Adjust the Gain setting to get a signal which has an amplitude of 900 ADC counts 4 Se...

Страница 16: ...rd Deviation 5 2 Zero Flow Drift Testing Zero flow drift testing is often used as a measure of the minimum detectable flow of a meter and accuracy in low flow The minimum detectable flow of a meter is related to the zero flow drift and the sensitivity of the meter A meter with higher sensitivity and lower zero flow drift will have a smaller minimum detectable flow The minimum detectable flow is li...

Страница 17: ...on of ice or hot water to the tank with a thermocouple recording the water temperature A video discussing flow measurements and setup can be found at Ultrasonic Water Flow Meter Demonstration Figure 5 2 Flow Test Setup Flows are typically captured over several minutes and averaged to compare accuracies between a reference meter and the DUT Figure 5 3 shows comparative flow tests results for a mete...

Страница 18: ...Page numbers for previous revisions may differ from page numbers in the current version Changes from March 28 2020 to September 17 2020 from Revision A March 2020 to Revision B September 2020 Page Added MSP430FR600x to list of devices covered by this guide 2 Added Section 1 4 2 Revision History www ti com 18 Water Flow Meter SLAU810B SEPTEMBER 2019 REVISED SEPTEMBER 2020 Submit Document Feedback C...

Страница 19: ...o change without notice TI grants you permission to use these resources only for development of an application that uses the TI products described in the resource Other reproduction and display of these resources is prohibited No license is granted to any other TI intellectual property right or to any third party intellectual property right TI disclaims responsibility for and you will fully indemn...

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