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.
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 I2
C or SPI connection for fast, reliable data transfer to the microcontroller.
||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
||ADE7953: Single Phase Multifunction Metering IC with Neutral Current Measurement
|Tilt, Motion, Vibration
||ADXL345: 3-Axis, ±2 g/±4 g/±8 g/±16 g Digital Accelerometer
||AD7151: Ultra-Low Power, 1-Channel, Capacitance Converter for Proximity Sensing
||ADMP401: Omnidirectional Microphone with Bottom Port and Analog Output
||AD7792: 3-Channel, Low Noise, Low Power, 16-Bit Sigma Delta ADC with On-Chip In-Amp and Reference
||ADA4528-1: Precision, Ultralow Noise, RRIO, Zero-Drift Op Amp
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.
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.