mipi - Discusses a Machine Independent Parallel Interfac

mipi - Discusses a Machine Independent Parallel Interfac -...

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Machine Independent Parallel Interface (MIPI) ============================================= Version V-0.0 14th August 1995 David Tait Electrical Engineering Dept The University Manchester M13 9PL UK [email protected] Copyright (C) 1995 David Tait Permission is granted to copy, store or redistribute this document provided the information contained herein is not exploited for profit and the document remains intact and unmodified. This document contains ASCII diagrams and you should select a mono-spaced font for correct viewing; a proportional font will wreck them. Introduction ============ To the electronics hobbyist perhaps the most useful interface on an IBM PC or compatible is the parallel port. All manner of hardware can be attached to this port and subsequently controlled with a few lines of C or BASIC. Of course not all personal computers are IBM clones and some may not have a parallel port at all. It can happen that the owners of these errant machines are also electronics hobbyists. I suppose these people must be resigned to the absence of such a useful facility on their PC, but I suspect that they also feel disenfranchised when they come across yet another project that might have been fun to build if it hadn't relied on a parallel interface. I find it annoying that I cannot use my desktop Sun workstation to play with the little gizmos that are such a breeze to use with my IBM compatible. Many of these toys are based on chips that incorporate serial peripheral interface (SPI) or inter-integrated circuit (I2C) connections. It is pretty straightforward to attach these devices to a PC by "bit-banging" the SPI/I2C protocol using the parallel port; they are not so easy to use without a parallel interface. Although the parallel port may or may not be present on a given PC, it is almost certain that the same PC will have a serial port (often called, whether correctly or not, an RS232 interface). This is fine for connecting a modem, a mouse or even another PC, but it is not so useful for connecting simple homebrew hardware. There are several reasons for this: firstly, the signalling rate of the serial port falls far short of that possible using the parallel port; secondly, relatively complex hardware is needed to decode the serial data stream; and thirdly the voltage levels are not convenient. On certain systems (notably the IBM PC again) it is possible to use the modem signals (CTS, DTR, RTS, DSR and DCD) as general purpose I/O. After level conversion these are great for many projects, however, it's unlikely that all machines let you fiddle with these lines, use them in a uniform way, or even possess them in the first place. Of course, there are many projects where speed is not important and in this case the main reason for not using the serial port is the hardware overhead. Even this is really only an impediment if the decoding hardware has to be
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This note was uploaded on 02/18/2012 for the course ECE 101 taught by Professor Binsaprat during the Spring '12 term at Albany State University.

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mipi - Discusses a Machine Independent Parallel Interfac -...

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