Priced at $ 249, this smart meter development board to "stealing people" dumbfounded

MSP Microcontroller Business Development Manager, Texas Instruments China

“The replacement of mechanical water meters with more accurate ultrasonic sensor measuring water meters is increasing. As far as we know, many newly opened real estate projects have adopted ultrasonic water meters. This is a new trend in the future.” MSP, Texas Instruments, China According to data provided by Yong Yong, a business development manager for microcontrollers, in the United States alone, more than 80% of suppliers have invested or planned to invest in smart water infrastructure to increase operational efficiency and reduce water losses. The revenue of the global smart water network market is also expected to grow from 2.6 billion U.S. dollars in 2016 to 7.2 billion U.S. dollars in 2025.

Ultrasonic technology for flow measurement

In most current designs of flowmeters, the active components use mechanical sensing, such as using an inductor capacitor (LC), giant magnetoresistive (GMR), tunneling magnetoresistive (TMR), or Hall effect sensor to capture the propeller or impeller. The movement, which varies according to the flow, is converted into data and passed to the measurement unit. Because of moving parts, wear and inaccuracies may occur.

These meters are generally short-lived (less than 7 years) and cannot detect low flows or small leaks. At the same time, media contamination, accumulation of dirt, and fouling and aging of components can also affect the measurement accuracy, which may result in inaccurate sensor results. Therefore, the flowmeter needs to be recalibrated on a regular basis.

Yong Yong believes that ultrasonic sensors can effectively avoid the above problems. Reasons include: Sensing technology is very accurate (< ± 1%), has a long service life (> 10 years), can easily detect different components of the liquid or gas, and adjust the media and pipeline corrosion pollution. Ultrasonic meters have no moving parts and therefore do not require recalibration.

From a technical point of view, the ultrasonic frequency range for flow measurement is from 100 kHz to 4 MHz. An electrical pulse signal of a certain frequency is used to excite the ultrasonic sensor to generate ultrasonic waves of a corresponding frequency, and the same acoustic wave transmission path is used to transmit sound waves from two opposite directions at different times and measure the time of flight. By calculating the absolute time difference between the uplink and downlink transmission times, the actual traffic is calculated.

One or more pairs of ultrasonic sensors mounted inside or outside the flow tube can be used to measure the TOF. The following figure shows the simple ultrasonic measurement principle and some common ultrasonic sensor layout topologies. The choice of ultrasonic sensor depends on the type of media of the fluid to be measured. In general, when the fluid to be measured is a liquid, an ultrasonic sensor having a frequency of 1 MHz or more is used, and when the fluid to be measured is a gas, an ultrasonic sensor having a frequency of 500 kHz or less is used.

20171101-TI-1 ultrasonic measurement principle and common ultrasonic sensor layout topology

The accuracy of the TOF measurement will directly affect the resolution and accuracy of the flow meter. TOF is usually measured in picoseconds (ps) or nanoseconds (ns). Its main parameters include zero flow drift (ZFD), standard deviation (STD), minimum and maximum detectable flow, flow, flow rate, volume, and absolute value ( Abs) TOF and Delta (Δ) TOF, International Organization for Standardization (ISO) 4064, OIML R49 and European Standard (EN) 1434 are the most common standards in the flow meter industry.

A truly integrated SoC

Unlike the same huge market for electric meters, water utilities are usually localized and far smaller than electric companies. Compared with the completion of smart meter installation, the emergence of Automatic Meter Reading (AMR) module and standard wireless communication network makes deployment costs even lower, which can help water companies effectively reduce operating costs on the basis of network operation.

The MSP430FR6047 is a series of microcontrollers recently introduced by TI for more accurate water metering and remote meter reading needs, with an integrated ultrasonic sensing analog front end, which can improve the accuracy of smart water meters and reduce their energy consumption. Yong Yong believes that this is a true integrated SoC, developers can use the complete waveform capture function and analog-to-digital converter-based signal processing functions to add more intelligent features to the flow meter.

The device has an average zero drift of 25 picoseconds or less and a standard deviation of 32 picoseconds or less, so a flow rate of less than 1 liter/hour can be detected, which is equivalent to the measurement of previous drop-out losses. The highly integrated architecture can reduce the number of water meter system components by 50% and reduce power consumption by 25%, allegedly ensuring that the water meter can operate for 10 years or more without charging the battery. In addition, the new MCU also integrates a low-energy accelerator module for advanced signal processing, a 256 KB ferroelectric random access memory, LCD driver and metering test interface.

The simultaneous launch with the MSP430FR6047 also includes two new reference designs that make it easier to design modules and add automatic meter reading capabilities to existing mechanical water meters.

The first is enabled by the single-chip SimpleLink dual-band CC1350 wireless MCU. This reference design also enables designers to add dual-band wireless communication to the AMR network. Designers can use the small size of the reference design to easily retrofit an existing mechanical flowmeter, enabling the water company to add AMR without having to replace the installed instrument. The CC1350 wireless MCU consumes only 4uA of current when measuring water flow, extending the life of the product.

The second new reference design is an ultra-low-power solution based on the SimpleLink Sub-1GHz CC1310 wireless MCU. The low-power wireless M-Bus communication module reference design uses TI's wireless M-Bus software stack and supports all wireless M-Bus operating modes in the 868 MHz band. This reference design provides best-in-class power consumption and flexibility, supporting wireless M-Bus deployment across multiple regions.

The MSP430 Ultrasonic Sensor Design Center offers rapid development and flexible customization of tools, including a software library, a graphical user interface (GUI), an evaluation module with metrology and digital signal processing libraries that developers can use to get the product to market within months.

Regarding whether to support the currently hot NB-IoT standard, Yong Yong stated that due to the huge investment in NB-IoT R&D, TI has not taken into consideration for the time being. The next generation of new products will improve ADC accuracy (to measure gases) and reduce FRAM capacity ( Reduce costs.

(Original title: Price $ 249, this smart meter development board to "stealing people" dumbfounded)

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