CC2430-based wireless sensor network system design (1)

In today's world, communication technologies, the rapid development, with MEMS, SOC, wireless communication and low-power embedded technology and the rapid development of the breed wireless sensor networks (Wireless Sensor Networks, WSN), and with its low-power, low cost, distributed and self-organizing feature brings a perception of the information revolution.

Based on this, the design implements a CC2430 as the core of wireless sensor networks. Among them, the sensor module includes a temperature and humidity sensor SHTll, infrared sensors and illumination sensors PGM5506 BS520.

1 wireless sensor network system architecture

Wireless sensor network is on the surroundings of temperature, humidity, light, acceleration, and other information for monitoring and management of technology.

This wireless sensor nodes built-in sensors, sensor control circuits, CPU, wireless communications module, antenna, power supply devices, through Ad-Hoc communication technology, and the surrounding sensor nodes along with the data transmission to the aggregation node. This article describes the wireless sensor network consists of one aggregation nodes and multiple sensor nodes, through the convergence of nodes on a remote host. The overall structure of the system as shown in Figure 1.

2 hardware circuit design

CC2430 is Chipcon's company launched to enable embedded ZigBee application of system on chip.

CC2430 only requires very few external components can run, its interior is integrated a lot of the necessary circuit, so using less peripheral circuit which implements the signal send and receive functionality. Figure 2 Basic circuit design for CC2430.

Figure 2 C1, C2 as the capacitor 22pF, connection 32 MHz crystal oscillator circuit, this quartz oscillator for normal work.

C3, C4 15 pF capacitance, connection 32.768 kHz crystal oscillator circuit of the quartz oscillator used to sleep while you work, thereby reducing power consumption. C5 = O £ ® 1 μ F, used to remove some clutter and prevent the SCM error reset. C6-C8 respectively 100 nF, nF F, 220 220n, used as a filter that removes noise interference voltage more stable. C9 = 5.6 pF, circuit non-balancing transformers and inductors from capacitance C9 L1, L2, and L3 as well as a PCB microwave transmission line components, the entire structure to meet the RF input/output matching resistor (50 Ω), L1, L2, L3 respectively 8.2 nH, nH, nH 1.8 22. C10, C11 and C12 and C13 to C14 to go to coupling capacitor for power filter, to improve the stability of the chip. Bias resistor R1 and R2 are 43 k, 56 k Ω Ω, R1 to 32 MHz crystal oscillator settings precision bias current.

Because CC2430 chips with low power characteristics, choose 2 section 2 800 mAh battery for node machine of supply.

Antenna selection for an external antenna.

CC2430 and warm humidity sensor SHTll, illumination sensors, infrared sensors PGM5506 BS520 connection schematic diagram shown in Figure 3, where P0.O, P0.1, P0.6, P1.2 and P1.3 as CC2430 i/o ports.

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