Design Of A Linear Displacement Sensor Based Diameter Increment Recorder

Diameter at breast height is a key indicator to describe the growth of trees. Generally, DBH isobtained by some manual measuring tools, such as strapping, tape or caliper. Because of the high cost offorest resources investigation and the long survey period which is more than5years, the manualmethods cannot get more precise information about the forest growth in time. In recent years, the rapiddevelopment of the sensor technology and computer technology provide a possibility for automaticmeasuring and recording about the growth of DBH. This paper designs a linear displacement sensor andthe SCM based recorder which can collect, store and transport the growth of trees. This design not onlyrealizes the goal in automatic, low-power and popularity, but also submits a method in reducing the costof forest survey and getting the diameter increment.Using a modular, open design and the minimum power consumption designing idea, this paperdesigns a long-term recorder powered by batteries. It choses TI’s MSP430F149as the core componentof controller and myne-tech’s carbon film ruler as the data sensor. This system includes trees growthcollection and A/D conversion module, data storage module, SD card communication module. Thegrowth of DBH is collected by the linear displacement sensor in analogue, then transported toMSP430F149.Through the A/D conversion, the data and the clock signal are all stored in the flash. Inorder to facilitate forest investigators, the system provides a SD card interface for transferring data.from the system to a SD card. When the card is inserted into the recorder, the SCM automatically copythe data from flash to the SD card. After completing and checking correct, the SCM romoves data fromthe flash and release the space. The system is designed to maximum power savings through setting thetimer, and it can work continuously for8months only with two1.5-volt batteries. The hardwareincludes the sensor detection circuit, reset protection circuit, power circuit, SD card memory circuit andthe external bracket.