| This paper mainly discusses the realization and design principle of experimental system-virtual instrument communicated with computer by USB. This instrument platform mainly consists of digitizing storage oscilloscope module, signal generator module, USB interface circuit and corresponding software.Firstly, this paper introduces the USB specification in detail, so we can know what job should be done in a USB device's development process. The following chapter describes the hardware design of the platform. The main chip of the USB interface circuit is a Cypress Semiconductor's product, CY7C64613, Which has intergrated USB SIE (Serial Interface Engine) and enhanced 8051. The oscilloscope module is realized according to the real time sampling principle. It has two signal chunnels and a dual 8-bit dual A/D converter whose most sampling rate is 40MSPS, so two signal acquisition can occurs in the same time. The signal generator is designed based on DDS (Direct Digital Synthesize) technique. Its output frequency range is from 10Hz to 5MHz and minimal resolution is 9.53Hz. Finally we introduce the software of the instrument platform. It mainly comprises of two parts, 8051 firmware and Windows application. |
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