What is ZigBee:
ZigBee is a mature wireless communication protocol with a long history of application in the field of smart lighting control.
ZigBee itself is a Mesh network with self-healing function. In the ZigBee network, devices are divided into three types: coordinator, router, and terminal node.
Coordinator: Establish a ZigBee network, manage routers and terminal nodes to access the network, and have the function of data routing and relay.
Router: It can assist the coordinator in maintaining the device connection of the existing ZigBee network, and also has the function of data routing and relay. The routing relay function of the router can help the coordinator expand the signal coverage distance and range.
Terminal node: After the terminal node is connected to the ZigBee network, it cannot communicate directly, and a coordinator or router is required as a parent node to forward its data transmission and reception. However, the terminal node can turn off the wireless transceiver circuit in the connected state to reduce power consumption.
In ZigBee's application layer protocol, the ZCL protocol, several different applications are subdivided into "clusters". Each "cluster" is an application specification. In a cluster specification, the behavior of the device controller and the controlled end are subdivided, including what instructions the controller sends, what operations the controlled end performs, and what status the controlled end returns. Usually a ZigBee device will support multiple cluster specifications at the same time, and ZigBee devices have three different roles: coordinator, router, and terminal node. ZigBee devices realize a variety of different device functions by permuting and combining different cluster specifications and permutations and combinations of the three roles.
Lighting control system and intelligent lighting control system:
In a typical lighting control system, according to the traditional architecture, the system has two types of devices: control end device and controlled end device. The control end device is the switch, and the controlled end is the lamp. In the traditional lighting control system, the switch controls the lamp by turning on and off the power supply of the bulb. This application method can only control the on and off of the lamp, and it is difficult to control the brightness and color, especially since today's lamps are LED lamps using semiconductor lighting technology, and the brightness and color cannot be adjusted by turning on and off the power supply circuit.
In the era of LED lamps with popular semiconductor lighting, intelligent lighting control technology has also become popular. This type of lamp is usually based on an integrated MCU for controlling LEDs. When in use, this type of lamp is connected to a connected power supply circuit to provide continuous power supply. The control end of the lamp usually controls the lamp by wireless remote control. Of course, there are also some protocols that use wired control, such as DALI bus or power carrier. The intelligent lighting control system using wired control needs to solve the compatibility problem of the control signal line and the power supply line, which increases the construction difficulty, while wireless lighting control does not have construction problems, so mainstream intelligent lighting control mostly uses wireless control.
Why ZigBee is suitable for smart lighting control systems:
Since ZigBee is a wireless network with a Mesh structure, in the smart lighting control system, the controlled end device (light bulb) can be implemented as a router, and the signal coverage range can be increased by increasing the number of light bulbs in the smart lighting control system. In particular, some lamps that need to be installed in signal blind spots can be solved by routers.
The ZCL protocol has a complete closed-loop control mechanism for each application cluster. For the smart lighting control ZCL protocol, three different application cluster specifications are defined, corresponding to on-off control, brightness (level) control and color control. At the light bulb end, the arrangement and combination of these three clusters can be selectively supported according to needs, so that three different lamps, namely, on and off lights, dimming lights, and colored lights, can be realized, and they can be controlled by the same control end.
Functional implementation:
Control end and controlled end in ZigBee smart lighting control system:
It was mentioned before that the lighting control system must have two devices - control end and controlled end. In fact, any control system is composed of control end and controlled end. In the ZigBee-based smart lighting control system, there are usually two types of devices on the controlled end, namely independent light bulbs and switches with relays (commonly known as single-control switches). There are usually two types of devices on the control end: wireless switches (commonly known as single-control switches or lighting control remote controls) and gateways with APPs. In the subsequent introduction, these four types of devices are called: light bulbs, switches, remote controls, and gateways.