Embedded solution for a microwave moisture meter

In this paper, the conversion of a PC or laptop-controlled microwave moisture meter to a stand-alone meter hosting its own embedded system is discussed. The moisture meter is based on the free-space transmission measurement technique and uses low-intensity microwaves to measure the attenuation and phase shift of the sample, from which the dielectric properties are calculated. The dielectric properties are then used for instantaneous and nondestructive determination of the moisture content in the grain or seed sample. The previous system consisted of the moisture meter and measurement procedure being controlled via USB interface by an external laptop or PC. Though effective, the system lacked full portability and was susceptible to computer failure and interruptions in communication between the meter and computer. To improve the system, a microcontroller was selected in the design of an embedded system for the moisture meter, making it a stand-alone system. The microcontroller provides a graphical 144 × 32 pixel LCD and 16-button keypad to facilitate user interaction. The embedded system provides the following functionalities: user interface (input/output), event execution, process control, data acquisition and data storage. The integration of the embedded system with the microwave meter provides a portable, robust, and cost-effective solution for microwave moisture sensing.