Usb-based Automatic Test System Design

The use of the Smart Instruments is the most common form in present electric measurement. The logical ability of the instruments is stronger and the use of it is more convenient. The present Smart Instruments has general interface and its' communication protocol accords with GPIB standards or IEEE-488 standards. So the given Test tasks can be analyzed concretely and Automatic Test System can be established.A special controller is adopted as the director in Automatic Test System. For example HP-85 produced by Hewlett-Packard Company is a special controller of GPIB. But this special controller is very expensive. Through analyzing the communication protocol of GPIB system, the author of this research paper uses the most common SCM as the control core in hardware and compiles the corresponding communication protocol in C51 language in software. At the same time the general commands function group is compiled which makes the communication between the controller and the Smart Instruments realized by calling in simple functions. This system can definitely replace the expensive special controller completely.In order to make the system possessing more universality and more convenient interface, A USB interface is expanded in hardware. The data of Test are transferred to PC by the USB interface. At the same time the application program can be complied to control the Automatic Test System in PC. In this item PDIUSBD12 produced by Philip Company is used as USB control chip to transfer USB data. The communication between PC and PDIUSBD12 is realized through calling in API Function in dynamic link libraries EasyD12.dll.The Quality (Q) factor is an important parameter in measuring the performance of an antenna. It can be measured by a function generator and an oscilloscope .A great deal of data should be recorded and calculated during Test. An Automatic Test System can be adopted to analyzing the character of the test. The hardwares of this item include 8116A PROGRAMMABLE PULSE/FUNCTION GENERATOR of Hewlett-Packard Company, TDS1012 TWO CHANNEL DIGITAL STORAGE OSCILLOSCOPE of Tektronix Company, the GPIB-USB Interface Card and PC. The software includes the application programs in PC and the firmware in Single Chip .The Quality (Q) factor can be automatically tested through the mutual cooperation combination of the hardwares and the softwares.