Application of LoRa in Thermostat

As early as 2005, the state issued a document to promote the system of metering and charging for heating according to heat consumption. However, after more than ten years, due to the difficulty of implementing household metering, high technical barriers, high construction costs and many other reasons, progress has been slow. In fact, this situation exists not only in heat metering, but also in many similar applications of temperature control instruments, energy metering, and energy efficiency management. The introduction of wireless technology, including the gradual improvement of wireless solutions such as 433 and zigbee, has gradually solved such problems. The release of LoRa technology, with its transmission advantages in complex indoor environments, has completely changed many problems such as difficulty in entering households, construction, and monitoring.

Figure 1 Topology of wireless heat metering system

Advantages of LoRa wireless transmission solution

In fact, wiring in energy metering, energy management, and communications is very difficult. Wireless transmission is an absolutely dominant solution. Currently, many solutions such as RS-485 and M-bus in the industry are gradually replacing them with wireless to achieve system normalization. In terms of wireless transmission, the LoRa solution has more advantages in this field:

1. Wireless communication effectively solves the problems of construction wiring, installation and maintenance in the complex environment of the building. It has the advantages of simple installation and maintenance, no wiring required, saving construction costs, and shortening construction period.

2. LoRa wireless spread spectrum technology has a receiving sensitivity of -148dBm. Compared with traditional 470MHz transmission, it has more than twice the communication distance and coverage area (the temperature control panel can basically cover five floors), greatly reducing the number of gateways and construction costs;

3. LoRa uses ISM band wireless communication technology. In actual applications, the numerous wireless signals in urban environments are already very crowded, which will have a strong interference effect on wireless communications. LoRa integrates digital spread spectrum, digital signal processing and forward error correction coding to effectively ensure the stability, reliability and anti-interference ability of wireless communications.

4. Ultra-low power consumption design, battery-powered thermostat with a service life of up to 3~5 years.

LoRa module application case

Figure 2 Application example of LoRa wireless module in thermostat

Case Study

Node solution:

The communication between the thermostat and the gateway uses the LoRa wireless module ZM470SX-M, which is designed with an ultra-small size (15.0mm×15.0mm) and has the characteristics of low power consumption and long distance. Since thermostat products may involve applications such as wall burial, there are certain requirements for the layout of LoRa antennas. ZLG Zhiyuan Electronics also provides customers with various antenna layout assistance services, providing effective guarantees for customers to shorten the R&D cycle and improve the overall competitiveness of products.

Figure 3 LoRa module ZM470SX-M

Figure 4 Temperature control product structure diagram

Gateway solution:

ZLG Zhiyuan Electronics has launched the intelligent wireless gateway Iot-3968 for the industrial Internet field. It uses ARM9 as the core, adopts a two-way MiniPCIE interface design, and provides a variety of optional wireless interface modules (using MiniPCIE interface design, including Wi-Fi, ZigBee, LoRa, GPRS/3G/4G, etc.), which makes it easy for customers to quickly build intelligent IoT gateway products suitable for their own industry.

Figure 5 Iot-3968 Smart Wireless Gateway