摘要
基于EZ -USBFX2系列USB(通用串行总线)单片机中的GPIF(通用可编程接口)功能和USB2. 0接口功能,模拟EPP(扩展并行端口)的全部读写时序,使得PC能够通过USB接口与EPP接口设备进行通信。方案中通过PC上的驱动程序和转换板上固件程序实现了USB接口的控制、中断、批量3种传输方式,通过使用Cypress公司提供的GPIFDesigner工具开发GPIF,预先定义好波形描述符,在程序执行过程中通过激发GPIF功能来模拟EPP的数据读写、地址读写时序,完成USB协议与EPP协议的双向转换。此方案硬件实现简单,具有可靠性高、传输速度快、占用CPU及内存资源少等特点,是扩展PC上EPP接口的良好选择。
This paper simulates the time sequence of EPP on the platform of EZ-USB FX2GPIF-an MCU with GPIF and USB2.0 interface, and realized the communication between the EPP and USB. Using the PC drivers and the firmware on the board, the PC can transfer data through USB in three modes: control, interrupt and bulk. This method uses the Cypress GPIF designer tools to design the GPIF-define the wave descriptor. Using GPIF to simulate EPP reading and writing sequence, the signals between USB and EPP can be successfully converted. This scheme is easy to realize. It needs only little CPU and RAM resource. Data can be transferred with high speed and reliability. This scheme is a good choice for expanding the EPP on PC.
出处
《电子工程师》
2005年第4期55-58,共4页
Electronic Engineer
