Newsgroups: comp.robotics
Path: brunix!uunet!snorkelwacker.mit.edu!news.media.mit.edu!fredm
From: fredm@media.mit.edu (Fred G Martin)
Subject: Re: Miniboard 2.0 & NMI F68HC11
Message-ID: <1992Aug27.205711.23050@news.media.mit.edu>
Keywords: Miniboard
Sender: news@news.media.mit.edu (USENET News System)
Organization: MIT Media Laboratory
References: <1992Aug26.192907.10931@aio.jsc.nasa.gov> <1992Aug27.010906.1515@news.media.mit.edu> <1992Aug27.142429.16553@hubcap.clemson.edu>
Date: Thu, 27 Aug 1992 20:57:11 GMT
Lines: 24

In article <1992Aug27.142429.16553@hubcap.clemson.edu>
dawill@hubcap.clemson.edu (david williams) writes: 

>   Looking at the miniboard schematic, I would say that disabling the 
>hardware echo is going to be a semi tough, but not impossible, task.

  [ explanations and ideas for fixing it follow]

Personally, I would think that the appropriate things to do are (1)
modify your software to deal with the hardware, or (2) flat out
replace the Mini Board's hacked-up serial line solution with something
normal, like the one-chip Maxim MAX233 solution.  This chip has
built-in charge pumps and voltage inverters for generating legitimate
plus and minus ten volt supplies from a single +5v supply.  Pretty
neat!

It's a tough call; maybe the Mini Board should have used this
solution.  It would have added board area and a few dollars of parts
costs, but then people wouldn't be hassled with serial line
weirdnesses.

Oh well.

	- Fred
