THE DEVELOPMENT OF SIMPLE, LOW-COST AND POWER-EFFICIENT PIC-BASED WIRELESS SENSOR NODE AND ACCESS POINT

Wireless sensor network (WSN) has been attracting growing interests for new development of much improved power efficiency, lower cost and smaller size without sacrificing the robustness and reliability of the sensor nodes. The advances in new embedded technology have made it possible as more features can be integrated into tiny but high performance processor, sensor and hardware. However, this high-end technology has cost the consumer to spend quite expensive investment which is not appropriate for simple data acquisition application in unsecured places. It is not practical and economical when the sensor nodes are lost or failed in the environment. This paper describes the design and the development of simple wireless sensor nodes and access point by using Peripheral Interface Controller (PIC) for low rate data logging application. It is to be integrated to the high-end WSN as the extension to the available sensor nodes or base station for large deployment in unsafe places. The project involves the hardware and software design of low-power and economic wireless sensor nodes. The nodes are configured manually to transmit the temperature data one node at a time to prevent interference of the shared 433MHz frequency band. PIC controls the operation of the wireless sensor node and access point for data encoding, decoding and the operating or sleep state of the nodes. For low cost sensor nodes, cheap RF modules, low-pin PIC and tiny-sized nodes are taken into consideration. To improve the data reliability in compensating the noisy cheap RF modules, useful PIC features such as timers, counters and interrupts are used to produce Manchester encoded and decoded data. In terms of power efficiency, the circuit design and hardware selection of eXtreme Low Power (XLP) PIC improves the energy consumption in addition to the integration of sleep mode to the nodes.