Path: utzoo!censor!isgtec!bmw
From: bmw@isgtec.UUCP (Bruce Walker)
Newsgroups: sci.electronics
Subject: Re: UARTs, uControllers, & Serial Data
Message-ID: <606@isgtec.UUCP>
Date: 21 Aug 90 14:32:37 GMT
References: <21000091@m.cs.uiuc.edu>
Reply-To: bmw@isgtec.UUCP (Bruce Walker)
Organization: ISG Technologies Inc. Mississauga Ont. Canada
Lines: 37

In article <21000091@m.cs.uiuc.edu> totty@m.cs.uiuc.edu writes:
> 	(1) What simple UARTs to people recommend, especially simple ones
> 	    whose options can be hard-wired and not require writing words
> 	    or initialization data to the UARTs?

I don't have an SMC catalog handy but they have several UARTs like you
need.  There is an "industry standard" 40 pin device where the input
and output busses are separate and all control lines are brought out
to pins.

> 	(2) Are there any chips to do what I want (synchronous serial to
> 	    RS-232)?

Don't know, never heard of one.

> 	(3) Would it make sense to use a microcontroller instead?  If so
> 	    what microcontrollers are recommended, how wide are their I/O
> 	    paths, and what support circuitry do they need?  Are they
> 	    easily programmable?

The Hitachi 64180 (aka Zilog Z180) has both synchronous i/o and async
serial ports but the synch port is extremely limited in cababilities.
These uP's have an improved Z80 instruction set. I/O is 8 bits.  Support
ccts would be minimal, they have xtal oscillators and most i/o you need
built-in; you might need to decode ROM/RAM addresses but even there you
get 20 pins of address (built-in MMU) so you can be wasteful with
address space.

I'd tend to use a couple of PAL's and a 40 pin UART myself.  A state
machine to do this would be simple (all the terms would fit in a 16R4,
likely) and you'd need a shift register for the sync input part.  If
you can get AMD to give you PALASM for the PC you get a reasonable
state-machine syntax to describe your FSM therefore eliminating a major
headache.

-- 
bmw@isgtec.uucp  [ ..uunet!utai!lsuc!isgtec!bmw ]  Bruce Walker