Smart meter solutions discussed by various companies

Smart meters have always been a hot topic, and major semiconductor manufacturers have taken advantage of this momentum to recommend their own products and solutions. Today, I will briefly introduce to you the main products of each company in the field of smart meters.

Smart Grid Block Diagram

I couldn't help but use this picture on Freescale's official website. Although the labeling on the picture is not necessarily complete, it presents us with a framework of the entire smart grid. Metering, as the most basic and important function of the meter, is also prominently marked in the picture. Of course, as a smart meter, we have more requirements for it, and how can it meet people's diverse needs? First of all, it must have a strong "core" - MCU.

Control unit MCU comparison

As the brain of the smart meter, MCU has always been the most important module. It is responsible for the processing and display of sampled data, and is also responsible for the exchange of external data streams. It can be said that its performance directly determines the performance of the smart meter. From the current main smart meter solutions, the MCUs used basically include LCD display interface, RTC real-time clock, various communication interfaces, such as RS485, PLC, wireless module, etc. Of course, for solutions at different prices, the configuration is slightly different. Let's look at the MCU products of major semiconductor manufacturers:

1) Freescale, for low, medium and high-end smart meter requirements, Freescale has S08MZ, S08GW series, MCF51EM series, and Kinetis K30 series. Freescale provides 8-bit and 32-bit microcontroller solutions, especially the MZ series microcontroller, which is specially customized for the new standards of China's smart grid.

2) STMicroelectronics, also 8-bit and 32-bit MCU solutions. The STM8L low-power series focuses on the low-end market, while the STM32 series and the configurable microprocessor SPEAr series are responsible for the mid-to-high-end market.

3) Texas Instruments, MSP430 series, is an ultra-low-power 16-bit microcontroller solution.

4) Atmel, from 6-pin Atmel tinyAVR to megaAVR, AVR XMEGA, 32-bit AVR, Cortex-M3, ARM7 and 400MHz ARM9 and many other 8-bit and 32-bit microcontrollers.

Judging from the solutions launched by various companies, they basically use 8-bit controllers for the low-end market, and 32-bit controllers for the mid-to-high-end market. Texas Instruments mainly promotes the 16-bit MSP430 series for the smart meter market. For the low-end market, it has the MSP430AFE2 series, and for the mid-to-high-end market, it also has 4 series of products. Compared with other companies, it is just a different market strategy.

Due to the special requirements of the application, the energy consumption requirements of the meter are relatively high, so the ultra-low power consumption products of various companies must also be mentioned. Such as Freescale's S08GW series and S08LL series, STMicroelectronics' STM8L and STM32L series, Texas Instruments' MSP430AFE2xx and MSP430FE47X2 series, Atmel's tinyAVR, megaAVR and AVR XMEGA series using picoPower technology.

In terms of functional module SoC solutions, Texas Instruments seems to do better. The low-cost MSP430FE47x2 MCU reduces the MCU system components to one-fifth of the original by integrating the ESP energy calculation engine with 2x16-bit Σ-Δ ADC, 128-segment LCD driver, up to 32KB of flash memory and 1KB of RAM, and a real-time clock.

The MSP430FE47x2 MCU SoC solution reduces the number of MCU system components to one-fifth of the original

Comparison of communication schemes

At present, the domestic communication methods used are RS485 or PLC carrier communication. 485 communication requires additional wiring, which is too large to be implemented on a large scale; and the carrier communication in China is currently completely narrow-band FSK carrier, which also has many problems. First, the load characteristics of the power line have a greater impact, which can easily cause the instability and unreliability of the communication channel, and the transmission rate of the FSK carrier scheme is not enough to meet the requirements of real-time communication.

At present, the Middle East and Europe are deploying the PRIME or G3 standard, which is an OFDM carrier communication method with a rate of 20K-100K to ensure the requirements of real-time communication. This is also a solution promoted by many companies; and there are also some improvement schemes for the current FSK modulation technology. Taking the S-FSK modulation technology of ON Semiconductor as an example, according to the characteristics of the power line, the automatic switching of S-FSK and ASK is adopted to deal with the most common narrowband interference. In general, the PLC Modem works in the so-called S-FSK modulation mode: the two carrier frequencies are far apart (>10 kHz). If narrowband interference affects a certain carrier frequency, the Modem can also use another carrier frequency for communication. At this time, the modem works in ASK modulation mode. Let's take a closer look at the products of each company:

1) Freescale, MC13260 communication chip for OFDM and S-FSK carrier modes;

2) STMicroelectronics, ST7590 for OFDM mode, ST7538Q and ST7540 for B-FSK mode, ST7570 for S-FSK mode, and ST7580 for B-FSK, B-PSK, Q-PSK, 8-PSK modulation modes;

3) Atmel, ATPL2xx series for OFDM and fully compatible with PRIME communication modules;

4) Maxim, mainly promoting G3 communication solutions, product model MAX2992, the first chip in the industry; for OFDM mode, Maxim is also the first manufacturer in the industry to launch the corresponding chip, model MAX2990;

5) Texas Instruments, based on the C2000 MCU platform, can flexibly customize solutions for customers for SFSK, FSK, G3, PRIME, P1901.2 OFDM and other standards. Unlike other manufacturers who use ASIC dedicated chips, Texas Instruments uses DSP solutions. For different technical standards, users can launch corresponding solutions by simply upgrading different software protocol stacks without changing the hardware. Among

wireless solutions, each company basically focuses on ZigBee, such as Freescale's MC13202, MC1322x, STMicroelectronics' SPZB250, 260, etc., Texas Instruments' CC2520/CC2530, and CC2500/CC2550, etc. Of course, many MCUs themselves have SoC wireless modules in them, such as STM32W, etc., so I won't go into details here.

Comparison of security functions

I personally think that security mainly includes two aspects. On the one hand, how to ensure the security of meter data, how to prevent data loss in power failure or other situations, and how to prevent tampering; on the other hand, how to ensure the security of data transmission, how to ensure the security of some privacy information of individual users during data transmission, etc.

At present, all smart meters have ESAM security modules, which can basically meet the above requirements. And what solutions and products do various semiconductor manufacturers have to ensure security? Let's take a look at them in detail:

1) In terms of anti-tampering, Freescale has a variety of sensors to choose from, such as acceleration sensor NMA745xL, proximity sensor MC33941, pressure sensor MP3V5004, etc.;

2) STMicroelectronics has a dedicated management chip M41ST87W for RTC (real-time clock); of course, some MCUs themselves have RTC modules, such as Freescale's MCF51EM256, etc., so there is no need for a separate management chip.

3) Texas Instruments' ZigBee wireless communication chip is equipped with an AES128 encryption module, and it provides users with a variety of encryption algorithms, which customers can flexibly select and configure.

Smart meters are more government-led, so their growth is relatively stable compared with other fields. This is also the main reason why major semiconductor manufacturers are competing for this market.

From the perspective of products and technologies, each company has its own advantages. For example, Freescale has a relatively complete product line, and it covers all products with the concept of smart grid. In addition, its advantages in sensors provide a variety of sensors for the design of smart meters in terms of safety. STMicroelectronics provides a variety of microcontroller options, and various power modules and power chips also provide a variety of options for the design of smart meters. Texas Instruments, MSP430, is a very competitive product in the smart meter solution in terms of power consumption and cost performance, and many SoC solutions of Texas Instruments make it possible to design smaller products at lower costs. Moreover, these manufacturers have actively participated in the formulation of various standards to provide support for the improvement of smart meters.

Some other semiconductor manufacturers also focus on specific fields. I believe that they will have their own place in the field of smart meters in the near future.