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, Nuvoton microcontrollers and Winbond NOR Flash memories will be introduced in this article.

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.

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 Nuvoton NuMicro M2354 microcontrollers and Winbond W25X and W25Q NOR Flash memories.

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