As China's Internet of Things is entering the fast lane of development, ZigBee is gradually being accepted by more and more users in China. ZigBee technology has also been applied in some smart sensor scenarios. For example, ZigBee is used in the construction of the Beijing Metro Line 9 tunnel. ZigBee replaces the traditional RFID attendance system to achieve no missing reading, accurate direction judgment, accurate positioning and query, and improved tunnel safety construction. The management level; in some high-end elderly apartments, wireless positioning technology based on ZigBee network can realize real-time positioning and help function in the whole district in the nursing home or the elderly community. Since each elderly person carries a mobile alarm device with him, when the danger is encountered, the help button can be pressed in time to not only solve the problem of safety monitoring and rescue of the elderly during outdoor activities, but also is simple and convenient to use and has high reliability. This paper introduces the ZigBee Coordinator node design based on CC2530.
Node hardware overall designThe ZigBee wireless communication network is mainly composed of three nodes: a coordinator, a router, and a terminal device. At the beginning of the network establishment, each network has one and only one coordinator node, which is mainly responsible for network initiation, parameter setting, information management and maintenance functions, and can also be used to assist in establishing the binding between the security layer and the application layer. In view of the most complicated hardware and software design of the coordinator node, this paper mainly introduces the design method of the coordinator node. The coordinator node is mainly composed of a processor module, an RF front end, a power management module, and various external interfaces, and can also add sensors and GSM/GPRS modules as needed. The main hardware structure diagram of the coordinator is shown in Figure 1.
The processor module uses CC2530 as the main control chip [5]. The CC2530 is an IEEE802.15.4 compliant, true system-on-a-chip that supports proprietary IEEE802.15.4 and ZigBee, ZigBeePRO, and ZigBeeRF4CE standards. The CC2530 integrates a 2.4GHz RF transceiver, an enhanced industry-standard 8051MCU, a maximum of 256KB of programmable FLASH, 8KB of RAM and a comprehensive set of peripherals (including 2 USARTs, 12-bit ADCs and 21 general-purpose GPIOs). . At the same time, the CC2530 can be equipped with a standard compatible or proprietary network protocol stack (RemoTI, Z-Stack or SimpliciTI) from TI to simplify development with an RF transmit output power of 4.5dBm and a receive sensitivity of -97dBm.
(2) RF front endThe RF front-end uses TI's highly integrated RF front-end chip CC2591. The CC2591 operates at 2.4 GHz and integrates a power amplifier (PA) with a gain of +22 dBm, a low noise amplifier, a balun, a switch, an inductor, and an RF matching network. The receiving part has an integrated LNA receiving gain of up to 11dBm, a noise figure of 4.8dB, and a receiver sensitivity of 6dB, which significantly increases the coverage of the wireless system.
(3) Power management moduleThe system can be powered by external power supply and dry battery. When the external power supply is invalid, the dry battery can also be used to supply power to the system to ensure the normal operation of each node of the system.
(4) Interface moduleIn general, the coordinator node interface mainly includes a serial interface, a power interface, and a JTAG interface, and a USB interface can also be added. When the management machine has no serial port, the USB interface can make the node application more convenient and flexible.
(5) Antenna The antenna can be combined with an SMA antenna and an inverted F antenna. SMA is the abbreviation of Sub-Miniature-A, the full name should be SMA reverse polarity male, that is, the antenna connector is internally threaded, and the inner contact is a needle (the wireless device has external thread on one end and the inner contact on the inside). The wireless device of this interface is the most popular; the design of the inverted F antenna can be designed by TI, and the maximum gain of the antenna is +3.3dB, which can fully meet the requirements of the CC2530 operating frequency band.
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