Implementing an 8-Bit Asynchronous Interface with FX2LP
AN6077
Author: Sonia Gandhi
Associated Project: No
Associated Part Family: CY7C68013A
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Software Version: None
Associated Application Notes: None
Application Note Abstract
This application note discusses how to configure the General Programmable Interface (GPIF) and slave FIFOs of the EZ-USB FX2LP™ to implement an 8-bit asynchronous interface. The GPIF is a programmable 8 or 16-bit parallel interface that reduces system costs by providing a glueless interface between the EZ-USB FX2LP and different types of external peripherals. The GPIF allows the EZ-USB FX2LP to perform local bus mastering to external peripherals implementing a wide variety of protocols. For example, EIDE/ATAPI, printer parallel port (IEEE P1284), Utopia, and other interfaces are supported using the GPIF block of the EZ-USB FX2LP. In this example, it masters the slave FIFO interface of another EZ-USB FX2LP.
This implementation uses the GPIF Designer (an utility Cypress provides to create GPIF waveform descriptors) to design the application specific physical layer. The firmware is based on the Cypress EZ-USB FX2LP firmware ‘frameworks’. A hardware setup of two back-to-back EZ-USB FX2LP boards is also used, one acting as a master and another as a slave. Familiarity with the EZ-USB FX2LP development kit, examples and documentation on the development kit CD-ROM, and chapters 9 (EZ-USB FX2LP Slave FIFOs) and 10 (GPIF) of the EZ-USB FX2LP Technical Reference Manual is assumed.
Introduction
The objective of this application note is to:
■Demonstrate a glueless interface to an 8-bit peripheral data bus (the FIFO of a slave EZ-USB FX2LP).
■Use EZ-USB FX2LP to transfer data to and from the pe- ripheral (slave EZ-USB FX2LP) and the USB host.
This application note discusses the necessary hardware con- nections, internal register settings, and 8051 firmware imple- mented to execute data transactions over the interface and across the USB bus.
Figure 1. Hardware Connection Diagram
February 19, 2008 | Document No. 001-15342 Rev. ** | 1 |
