Ultrasonic sensing gas flow metering

I'll be demonstrating our MSP430FR6043 ultrasonic sensing MCU in a gas metering application. You can get more details or purchase the EVM on TI.COM. The MSP430FR56043 provides extremely accurate flow measurement results exhibiting ultra-low power consumption. We also provide some powerful tools to get you up and running with a working meter in less than 2 minutes. We have results that show better than plus or minus 1% error across a wide dynamic range of flow rates, less

Than 20 micro-amps of average current for flow measurement.

To evaluate TI's MSP430FR6043 gas metering solution, we need the evaluation module, the EVM MSP430FR6043, and two ultrasonic transducers mounted to a gas pipe. The pair of transducers should be connected to the EVM as shown here and a USB cable connected to a Windows PC for GUI communication.

The EVM interfaces to a PC graphical user interface which enables configuration of the platform for use with various transducers and pipes. Once the USB cable has been physically connected to the PC, the EVM can be configured via the GUI. A configuration for the transducers and pipe can then be loaded via the load configuration button.

Once the configuration is loaded, the Request Update button should be pressed to send the configuration to the platform. The ADC Capture tab can then be used to preview and save upstream and downstream captures to a file. It's important to ensure the ADC capture is centered in the capture window since it will shift under temperature and flow. The capture can be shifted left or right by modifying this parameter in the Configuration tab.

The Frequency Sweep tab should be used to characterize the frequency response of the transducers being evaluated. As can be seen from this frequency sweep, exciting these transducers over the 170 to 240 kilohertz range should capture the full range of response for this transducer pair.

These parameters can also be adjusted in the Configuration tab. The Wave Forms tab can be used to capture and save delta time of flight, absolute time of flight, and flow rate data to a file. As can be seen from the GUI, the standard deviation of measurements is less than 500 picoseconds.

The accuracy of these measurements can be further improved by increasing the number of pulses in the Configuration tab. The trade off for using more pulses is a slight increase in current consumption. After introducing airflow by connecting a battery to the fan connected to our tube, we can see how these waveforms change over time, along with statistics on wave form measurements.

As you can see, you'll be up and running with TI's solution and a working gas meter in less than 2 minutes. For more information, please visit TI.COM/ULTRASONICMCUS.