Design And Implementation Of USB-PC104 Interface

By the developing of virtual instrument technique, the capability of measuring equipment has got a great advancement. But the current test and measure production are mostly based on VXI bus, PCI bus, PC104 bus or RS-232 bus. These forms of bus have many disadvantages, such as not easy to fix, high cost. Specially, the most important disadvantage is that they are restricted to the slot number, address and interrupt resources. Then the expansibility of equipment has been great limited.USB (Universal Serial Bus) is a brand new standard interface bus that can get over the shortage mentioned above. It has many advantages: has a relatively high transmission speed, the real plug-and-play capabilities, can connect with 127 peripheral equipments. So, it is very suit for the application in the measuring equipment.At present, the control function of many measuring equipment is achieved by FPGA (Field Programmable Gate Arrays). FPGA has many advantages, such as flexible structure, strong universality, suitable for blocking design. But the time sequence of USB bus is complicated that it is difficult to control. So, this paper proposes a solution to the problem: we can convert the complicated USB bus time sequence to simple PC104 time sequence. Then, the control function is easy to realize. At the same time, former PC104 bus measuring equipment can convert to USB bus measuring equipment very easily by use this method. But then, the transmission speed will decline a little.USB-PC104 interface can achieve the converted function, it adopt the EZ-USB FX2 (CY7C68013) chip as the main chip. It integrates the transceiver, SIE (serial interface engineer), the enhanced 8051 kernel and programmable periphery interface.Its unique structure makes the data transmission rate up to 56Mbps.This paper introduces the way using CY7C68013 to implement USB-PC104 interface, it presents the design of hardware, firmware, device driver and client application. By comparison, the design of hardware is relatively unsophisticated; the firmware is the key of converted function. The USB-PC104 interface is small in size, easy to design, has reliable converted function, and has application in USB12016 high-speed data acquisition card and other measuring production, can be used in a very wide field.