FPGA implementation of RS232 to Universal serial bus converter

Abstract

Universal Serial Bus (USB) is a new personal computer interconnection protocol, developed to make the connection of peripheral devices to a computer easier and more efficient. It reduces the cost for the end user, improves communication speed and supports simultaneous attachment of multiple devices (up to127)RS232, in another hand, was designed to single device connection, but is one of the most used communication protocols. An embedded converter from RS232 to USB is very interesting, since it would allow serial-based devices to experience USB advantages without major changes. This work describes the specification and development of such converter and it is also a useful guide for implementing other USB devices. The main blocks in the implementation are USB device, UART (RS232 protocol engine) and interface FIFO logic. The USB device block has to know how to detect and respond to events at a USB port and it has to provide a way for the device to store data to be sent and retrieve data that have been received UART consists of different blocks which handle the serial communication through RS232 protocol. There are a set of control registers to control the data transfer. The interface FIFO logic has FIFO to bridge the data rate differences between USB and RS232 protocols.