ST Demonstrates Smart-Grid Chipset and NB-IoT Module at Enlit Europe

December 01, 2023 by Arjun Nijhawan

At the Enlit Europe energy forum in Paris, ST highlighted a Prime v1.4-certified chipset for smart metering and an NB-IoT module for mobile devices.

This week at Enlit Europe (November 28–30), STMicroelectronics showcased an evaluation kit (EVLKST8500GH-2), including a smart-grid chipset comprised of a power line communication (PLC) SoC (ST8500), an ultra-low-power radio transceiver (S2-LP), and a dual-line driver (STLD1) enabling “hybrid” powerline and wireless connectivity. 



The new chipset includes ST's PLC SoC, the ST8500. Image (modified) used courtesy of STMicroelectronics

ST claims this chipset is the first to achieve the Prime v1.4 Hybrid Certification, a PLC communication protocol created by the Prime Alliance. The Prime (PoweRline Intelligent Metering Evolution) v1.4 protocol standard has been specifically augmented with “robust modes” to build resilience against noise in harsh environments using a repetition encoder. This repetition encoder duplicates bits in an encoded transmission sequence to increase the time and frequency diversity of the transmitted signal.


Smart-Grid Chipset Achieves Communication Certification 

The first chip in the evaluation kit is the ST8500. The ST8500 has already been on the market for several years and is equipped with a real-time engine to target different PLC standards. According to the datasheet, the ST8500 includes a 200-MHz, 32-bit Arm Cortex protocol core with 256 kB of embedded SRAM and a cryptographic engine with secure AES encryption. Additionally, it has a PLC digital front end (DFE) and analog front end (AFE) for sending and receiving signals using the grid. In between the DFE/AFE and Arm Cortex sits the real-time engine. 


ST8500 block diagram

ST8500 block diagram showing RTE, protocol core, and DFE/AFE. Image used courtesy of STMicroelectronics

The RTE flexibly handles time-critical aspects of PLC communication, such as modulation/demodulation and error correction. Just like other forms of communication, power line communication uses various protocols. Each of these may have different error correction and modulation schemes. Some examples of PLC communication protocols are HomePlug, G3-PLC, and Prime—the latter of which awarded the complete ST chipset with the v1.4 Hybrid Certification.


Prime v1.4

Prime v1.4 introduces robust modes to deal with noisy environmental conditions. Image used courtesy of Prime Alliance

The chipset uses ST8500 for PLC communication and the S2-LP ultra-low-power transceiver for wireless communication, enabling hybrid functionality. 


Block diagram of S2-LP

Block diagram of S2-LP. Image used courtesy of STMicroelectronics

The S2-LP is an ultra-low power transceiver designed to operate in the sub-1-GHz frequency band. It supports various modulation schemes, including 2(G)FSK, 4(G)FSK, and OOK. The ultra-low-power receiver has a supply current of about 7 mA in nominal conditions, while the transmitter has a supply current of 10 mA at 10 dBm. One of the main ways the S2-LP saves power is through its low-duty cycle mode (LDC), in which the receiver wakes up periodically instead of staying awake while waiting for an incoming packet. This reduces average power consumption. 


Low-duty cycle mode

Low-duty cycle mode reduces the power consumption of S2-LP. Image used courtesy of STMicroelectronics

Finally, the STDL1 line driver acts as a low-distortion, high-current amplifier to drive the output of BST8500 into a smart grid or similar application.  


NB-IoT Module Enters Volume Production

At Enlit Europe, ST also announced that its ST87M01-1000 NB-IoT module has entered volume production. NB-IoT stands for NarrowBand-Internet-Of-Things (NB-IoT). The primary goal of NB-IoT is to reduce the power consumption of user devices. According to the ST87M01's data brief, the device comes in an ultra-compact size (about the size of a postage stamp) and offers a low-power mode of < 2 ua. The fully programmable device supports both LTE and GNSS and provides up to +23 dBm power output. 



ST87M01 is designed for NB-IoT and GNSS applications. Image used courtesy of STMicroelectronics

ST has already released the first two variants of this device: the ST87M01-1000 NB-IoT module and the ST87M01-1100. The latter includes a GNSS receiver to support location-aware applications, like asset tracking. To achieve GSMA eSA (security assurance) certification, designers can also integrate a secure element. 


Supporting Smart Meters 

ST demonstrates both the smart-grid chipset and the NB-IoT module at a time when smart grid infrastructure requires higher-performing hardware. A smart grid relies on smart meters equipped with bi-directional communication between consumers and utility companies. Such meters take regular measurements of electricity consumption and must have reliable communication equipment in place operable over long distances. ST claims that the Prime v1.4 Hybrid Certification of its chipset paves the way for these meters to operate smoothly in smart homes and smart cities.