Hệ thống tưới tiêu thông minh sử dụng tính năng quảng cáo định kỳ có phản hồi (PAwR) của Bluetooth năng lượng thấp

With an ever-growing market of IoT and Industry 4.0 applications, a need for newer features arises to support these applications. The latest Infineon chip CYW20829 boasts a set of new features suitable for a multitude of these IoT applications. These features include Periodic Advertisements with Response (PAwR), low energy long-range (LE-LR), 2M PHY layer, etc. These features offer a novel perspective into the plethora of cool IoT applications. In this blog, we take a look at a smart irrigation system that employs PAwR.

What is a smart irrigation system and why do we need it?

Fig. 1: Each BLE+sensor node placed around the field.

For any big agricultural land or farm field, it is difficult to get accurate information on water requirements in each region. This can lead to inefficient use of water due to over-watering in some areas and under-watering in other areas. Also, there is no way to get real-time information. To tackle this issue, we propose a CYW20829-based IoT solution.

Fig. 2: CYW20829.

Each node will have a CYW20829 chip for Bluetooth and MCU requirements, and a few sensors such as pressure, soil moisture, humidity, etc. to check the corresponding parameters of the soil and this data will be sent over Bluetooth to a “Master node”.  We can have different levels of hierarchies depending on the size of the farm, and ultimately, make a decision on how much water is needed at what part in the field.

For this demo, we shall consider two levels of hierarchy, and employ the PAwR technique. (The Periodic Advertisements with Response is a new BT 5.4 feature that is supported in the CYW20829. Please check the appnote on PAwR for detailed information.)

Fig. 3: PAwR communication block.

Communication between PAwR advertisers and scanners

The PAwR will essentially help us with the synchronization of all the scanner nodes under an Advertiser (master) node. This will help in the seamless transmission of the data with limited energy needs.

There will be a master central station. The scanner nodes with sensor data shall carry a specific digit in their BDA for identification of the zone/region in the field.

Fig. 4: A PAwR master station communicating with PAwR servers.

The sensor data from the soil will be collected at particular pre-decided intervals, for example, the advertisement shall happen every 4-6 hours. For the rest of the duration, the nodes will be in sleep mode to preserve energy. The data will be sent over in adv packets in the adv window as decided during the synchronization phase.  The advertiser will collect and consolidate the data and pass it over to the master station using the same concept of PAwR where it is now the scanner with respect to the master station. The central station will analyze the data of a group of scanner nodes in a region, and if the readings drop below a certain threshold, it will indicate a signal to switch on the water supply for that region.

Phase 2

The same PAwR feature can be used in the reverse path to automate the process of switching on the valves of the drip irrigation system in those specific regions where water is required. The master station will take this decision and relay it to the scanner nodes through the cluster chain. The master station will also keep a record of Bluetooth device addresses corresponding to the devices for which it acts as an advertiser. The scanners on the lowest end of the chain, basically those placed around the field with a Bluetooth 20829 module, will be interfaced with a servo/stepper motor to switch on/off the valve.

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