WIRELESS SENSOR NETWORK (WSN) DEMO SYSTEM

The WSN demo system from Analog Devices can be used to demonstrate a complete Wireless Sensor Network (WSN). The hardware kit provides complete out-of-the-box functionality and includes a base station node along with multiple sensor nodes that support many different sensors. The system is flexible in that sensors can be connected in any combination to any of the sensor nodes.

The system uses the 868MHz/915MHz ISM Band for wireless communication. A proprietary protocol is included as the communication stack. The hardware blocks that make up a wireless sensor node are sensor, microcontroller, transceiver, and power management. These can all be evaluated using this demo system.

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Sensors

ADI offers a large selection of sensor technologies to monitor an array of environmental conditions. They all offer excellent performance for low power. Many have an I²C or SPI connection for fast, reliable data transfer to the microcontroller.

Sensor	Application	Part Number
Temperature	HVAC	ADT7420: ±0.25°C Accurate, 16-Bit Digital I2C Temperature Sensor
		ADT7410: ±0.5°C Accurate, 16-Bit Digital 2 Temperature Sensor
		ADT7310: ±0.5°C Accurate, 16-Bit Digital SPI Temperature Sensor
		ADT75: ±2°C Accurate, 12-Bit Digital Temperature Sensor
Energy Metering	Power Metering	ADE7953: Single Phase Multifunction Metering IC with Neutral Current Measurement
Tilt, Motion, Vibration	Security	ADXL345: 3-Axis, ±2 g/±4 g/±8 g/±16 g Digital Accelerometer
Proximity	Security	AD7151: Ultra-Low Power, 1-Channel, Capacitance Converter for Proximity Sensing
Sound	Security	ADMP401: Omnidirectional Microphone with Bottom Port and Analog Output
PH Sensor	Agriculture	AD7792: 3-Channel, Low Noise, Low Power, 16-Bit Sigma Delta ADC with On-Chip In-Amp and Reference
Gas Detector	Smoke Alarms	ADA4528-1: Precision, Ultralow Noise, RRIO, Zero-Drift Op Amp

Microcontroller

The microcontroller is the central component in the WSN signal chain. It communicates with all of the sensors to read and process the data that the sensors are measuring. It communicates with the radio, to package the data in a manner that the radio can transmit wirelessly. It also houses the memory, containing all of the system parameters such as sleep modes, and the RF communications protocol. ADI has a family of microcontrollers that are designed specifically for this extremely low power application space., such as the ADuCRF101 which is based on Cortex M3 processor technology.

ISM Band Transceiver

The radio is the component that takes the data from the micro, and transmits it wirelessly at an RF frequency to a basestation receiver. ISM band transceivers are used in this system. RF frequencies of 433MHz, 868-915MHz and 2.4GHz are supported to cover all of the available ISM frequency bands. The radio in this system is the ADuCRF101 ISM band transceiver IC with integrated microcontroller. This can operate in multiple frequency bands, 433MHz, 868MHz & 915MHz.

Power Management

The power management is critical to achieve maximum battery life. A Lithium coin cell battery or energy harvesting power source is the most typical power source found on a wireless sensor node. This voltage can be fed to the ADP160 LDO, which outputs the optimum operating voltage for the sensor node. In this example, a VCC of 1.8V to 2.5V would be optimal in terms of efficiency.