Smart Street Lighting: Alleviating Energy Cost Burden

Smart street lighting generally refers to any smart street lighting system with advanced technology implemented, like wireless modules, IP cameras, a variety of detection sensors, or other components. Different smart street lighting systems can be designed with various devices, depending on which functions they are about to provide. Among them, the wireless connection capability is necessary for smart street lighting systems to communicate with cloud servers and execute data analysis.

Street lighting occupies almost 40% of a large city’s energy costs, hence, the development of smart street lighting functionalities, such as smart LEDs installation, power monitoring and analysis, etc., will help city governments save more energy and cost. Other than this, any distinct device in smart lighting systems can achieve specific functions, for instance, cameras to monitor traffic conditions, speakers to alert people of danger, air quality sensors to detect contaminants, etc.

For smart street lighting implementation, a LoRa smart lighting control system and other important component solutions will be introduced in this article.

Being compatible with the ANSI C136-41 NEMA socket, the LoRa smart lighting control system from GlobalSat Technology Corp. can control streetlamps with ON/OFF/Dimming functions. It supports real-time power monitoring so that energy saving is reachable. In addition, it is certified with IP66 (Ingress Protection) rating.

Microcontrollers: Nuvoton NuMicro M2354 series

Based on Arm Cortex-M23, Nuvoton NuMicro M2354 microcontrollers are designed for IoT security-related applications, including smart street lighting. As smart street lighting systems will collect and analyze confidential data from cities, they require high levels of security.

In addition to being certified with PSA Functional API, PSA Certified Level 1, and Level 2, the NuMicro M2354 series has the built-in TrustZone architecture to realize software execution security; the chip-level security protection functions (such as debug port management, a Secure Key storage area, and others) to acquire data storage security; the voltage/clock glitch detection and CRC algorithm to avoid cyber-attacks and maintain connectivity security.

Running at up to 96 MHz, built in with 1MB dual-bank Flash memory, the M2354 series performs outstandingly on power management. It consumes 1.5 μA in the SPD mode, 0.5 μA in the DPD mode, and 89.3 μA/MHz (with LDO power supply) and 39.6 μA/MHz (with DC-DC power supply) in the Normal Run mode.

In summary, the chip-level security protection and low power consumption make Nuvoton NuMicro M2354 microcontroller extraordinary for smart street lighting applications.

Wireless communication modules: REYAX RYLR998 LoRa module & Alfa Wi-Fi HaLow™ module

Either LoRa modules or Wi-Fi modules can be applied to streetlamps, depending on which features users prioritize more – price, distance, or speed. LoRa can transmit tens of kilometers with up to 37.5 kbps data rate, while Wi-Fi can transmit tens of meters with the data rate of several Gbps (IEEE 802.11 ax and 2×2 Wi-Fi 6 supportive).

REYAX LoRa module RYLR998 was developed for applications that focus on stability and power saving, and smart street lighting is one of them. Built in with Nuvoton M031FB0AE microcontroller and Semtech LoRa engine, the RYLR998 module can transmit 20 km in an interference-free environment with 140 mA in transmit mode. RYLR998 has high sensitivity (-129 dBm), high interference immunity, and low receiving current (17.5 mA). Most of all, the smart receiving power-saving mode helps the RYLR998 save power with 2.7 mA average current and 20 μA minimum current.

Alfa Network Wi-Fi HaLow™ module is the recommended Wi-Fi option for smart street lighting. Built in with Newracom NRC7292 SoC and mikroBUS™, the Wi-Fi HaLow™ module supports IEEE 802.11 ah and UART, SPI, and I2C interfaces. Operating at sub 1 GHz, it can transmit approximately 1 km with up to 15 Mbps data throughput. Alfa Wi-Fi HaLow™ module allows the transmission of vehicle data, traffic condition data, and sensor data from streetlamps to control centers.

NOR Flash memories: Winbond W25X and W25Q series

Flash memories are indispensable for every application, and smart street lighting has no exception. The two dominant non-volatile memories are NAND Flash and NOR Flash, and in this case, NOR Flash fits better than NAND Flash with its fast random read speed, excellent code execution ability, and high reliability. Besides, application programs and embedded operating systems could be executed directly on NOR Flash, so XIP (eXecute In Place) is viable.

Winbond W25X and W25Q serial NOR Flash memories (SpiFlash memories) feature Serial Peripheral Interface (SPI) and Quad Peripheral Interface (QPI). The W25X family supports Dual-SPI, while the W25Q family supports both Dual- and Quad-SPI. The two families can double and quadruple the original SPI clock rates, respectively. For instance, Quad-SPI makes an equivalent clock rate of 416 MHz when the original clock rate is 104 MHz, with performance far greater than any ordinary 50 MHz Serial Flash memory. Therefore, controllers can execute code from the SPI interface through XIP (Execute in Place) or even shorten the boot time.

With high performance, small erasable sectors, and small form factors, NOR Flash memories with 8Mb～128Mb densities are especially suitable for smart street lighting implementation. In brief, the more functions a NOR Flash memory supports, the larger density it needs to be equipped with.

Conclusion

Smart street lighting has been trending in recent years. Its systems are a part of smart city development, so government regulations should be carefully considered during any deployment. Great solutions for smart street lighting have been introduced, such as GlobalSat LoRa smart lighting control systems, Nuvoton NuMicro M2354 microcontrollers, REYAX RYLR998 LoRa modules, Alfa Wi-Fi HaLow™ modules, and Winbond W25X and W25Q NOR Flash memories.

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