A Reusable UART IP Design and its Application in Mobile Robots

Abstract

A Universal Asynchronous Receiver and Transmitter (UART) is an integrated circuit which plays an important role in serial communication. The UART is a standard communication component that is provided by most of the available microprocessors. In general, the number of the UART in a microprocessor is limited and not enough for robot applications. In this chapter, a reusable Intellectual Property (IP) of UART design method by using VHISC Hardware Description Language (VHDL) is proposed and realized on a Field Programmable Gate Array (FPGA) chip. FPGA implementation is flexible because it can be easily reconfigured by the end user and reused for different designs. The proposed UART IP is composed of a baud rate generator, a receiver module, and a transmitter module. These modules are reusable and synthesizable. The popular N-8-1 (No parity (N), eight (8) data bits, and one (1) stop bit) data format is implemented in the proposed UART IP, but the parity setting, the number selection of data bits, and stop bits are user-enhancements. In this chapter, the proposed UART IP is applied to be a data detector of Infra-red (IR) ranging system to receive the distance information of objects, a data detector of digital compass to receive the head direction of robot, and a transceiver of a wireless modem to communicate with the other robots and a host computer. These application circuits have been implemented on a FPGA chip (Altera EP20K200EFC484-2X) to illustrate the robot can detect data from the IR ranging system and the digital compass exactly and communicate with the host computer and other robots successfully. The importance for System-on-Chip (SOC) using a reusable IP is increasing in modern design methodology. The old design method is not suitable to design chip which operates on a required function in a given time. Therefore, using proper IP for requested specifications can reduce the design time and cope with time-to-market (Delforge, 1998). In this chapter, a reusable UART IP is designed for applications in the serial communication. A UART (Harvey, 1999; Michael, 1989) is an integrated circuit, which plays an important role in the serial communication. The UART contains a receiver (serial-to-parallel converter) and a transmitter (parallel-to-serial converter). It handles the conversion between serial and parallel data. Serial communication reduces the distortion of a signal, therefore makes data transfer between two systems separated in great distance possible. In most computer systems, the UART is connected to circuitry that generates signals that comply with the EIA (Electronic Industries Alliance) RS232-C specification. The advantages of UART systems are the simplicity of interconnection wiring and character transmission protocol and formats. Starting with the original IBM Personal Computer, IBM has selected the National Semiconductor INS8250 UART for use in the IBM PC parallel/serial