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NuMicro® M2351 application series – Using long-distance wireless communication module, LoRaWAN Module as example

Posted: 30 Oct 2019, 19:07
by NuvotonMarcom
Nuvoton microcontroller application business group technical manager – Robert Ling


First of all, let’s start by explaining the two difficulties that IoT faces for large-area application scenarios; achieving range coverage and reducing power consumption for devices:
The main factors include the following three items:
I. Weak signal and large power consumption  It is difficult to cover deep into the ground because it requires frequent maintenance and battery exchanges
II. Poor coverage and large power consumption  The cost for large area deployment is very expensive and the positioning needs to be shifted
III. Power supply features of batteries  This is for devices that require a power supply from batteries due to wiring difficulties over long distances

According to the figure above, we can see there are communication problems when deploying a wide range of IoT devices, and then the way LoRa operates provides great solutions for these problems. Take a look at what we sorted out below.

Long transmission distance: Longer distance than a beehive/ Wider coverage range/ Star topology architecture
Long usage life: Low power consumption/ 10~20 year usage life/ >10x vs beehive M2M module
Wide range of uses: High capacity/ Multiple applications/ Public network
Low cost: Low-cost infrastructure/ Low-cost terminal nodes/ Open protocol

From the table above we can clearly understand the benefits of the LoRa standard; next, we will explain the LoRa Wide Area Network architecture. The basic connection architecture of LoRAWAN is similar to mainstream IoT communication architectures, except that LoRa uses AES-128 encryption, multi-channel upload and protocols for automatic adaption of network speed and data path; such network deployment requires consideration for many factors such as spectrum planning, data volume planning, coverage target (indoor or outdoor), power planning and business services to support. The following is a simple architecture diagram of LoRaWAN:
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Node reference design solution for LoRaWAN of NuMicro® M2351

We collaborated with the Lierda Company located in Hangzhou, China and are getting ready to launch module solutions based on the M2351 microcontroller with LoRa wireless communication integrated functions. In order to support international and China standards, we expect to launch two modules that are based on the two protocols international LoRaWAN Specification 1.0.2 and LoRaWAN CLAA 1.3.9 (China LoRa Application Alliance); the Armv8-M TrustZone architecture of M2351 is the best microcontroller selection to support such dual-standards. Since M2351 can provide TrustZone plus XOM functions, so different versions of communication protocol layers can be placed inside the TrustZone secure area or XOM (eXecute-Only Memory) based on the regional standard to comply with. The following benefits are provided from doing so:
1. The API of the communication protocol won’t be affected as much by the timing; it has fast response speeds and complies better with standards
2. It has a smaller dependence on specific microcontrollers and OS
3. The LoRa protocol cannot be easily tampered with and so is safer

Also, the LoRa wireless communication integrated function module has integrated radio frequency components and antenna matching components, reducing the trouble for designing wireless communication hardware significantly; the standard AT Command controls also provide product developers with convenient wireless communication control methods, allowing developers to have more time focusing on the development of application systems.

Nuvoton M2351 with LoRa wireless communication module architecture

We’ve sorted out the following table for explanation:
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From the architecture diagram described above we can see that compared to other average solutions, the reference design solution from Lierda for node devices based on LoRaWAN of M2351 does not need an additional microcontroller dedicated for processing wireless communication protocols; and with the rich peripheral functions of M2351, the two main chips included in the entire reference design module can fully satisfy the design requirements for communication and terminal products such as wireless metering, remote monitoring, smart homes, smart factory, smart buildings, and other IoT applications. In other words, it can be used as a communication module and it can also be designed for target terminal products.

Explanation of Nuvoton NuMicro® Family and Lierda’s LoRa solution and the market opportunities brought forth

As previously described, the operation of LoRaWANTM also requires gateways and base stations; these two play very important roles for connecting to IoT cloud service platforms; the MPUs (Micro-Processor Unit) from the Nuvoton NuMicro® Family can also play a role in the designing of gateways. For example, NUC980 is very suitable for developing the gateway for LoRaWANTM; the designs it can provide including indoor gateways for homes and industrial gateways. Through the cooperation of LoRaWANTM nodes, gateways and base stations, many IoT applications can be realized as shown in the table below.

Smart Industry
• Production status monitoring
• Efficiency management
• Asset tracking
• Park infrastructure monitoring
• Industrial environment monitoring

Smart Utility
• Smart metering (water, electricity, gas, and heat)
• Power distribution monitoring

Smart City
• Smart lighting
• Smart trash can
• Smart vending machine
• Smart manhole cover
• Smart parking
• Environmental monitoring
• Smart water platform
• Smart logistics
• Emergency management and more

Smart Building
• Efficiency management
• Security
• Illumination
• Heating and cooling air-conditioning
• Smart business building (Security)
• Smart homes
• Rental housing management

Smart Agriculture
• Smart irrigation
• Traceability of agricultural products
• Smart farming
• Agriculture and forestry environmental monitoring
• Livestock monitoring
• Reservoir management
• Water resource monitoring
• Medium and small river monitoring and early warning