Path: utzoo!news-server.csri.toronto.edu!rutgers!usc!samsung!munnari.oz.au!cow!bmp
From: bmp@cow.ecs.oz (Bruce Paterson)
Newsgroups: sci.electronics
Subject: Re: Favorite LCD display?
Summary: Some Notes to add AND
	 Query on GPS ?
Message-ID: <548@cow.ecs.oz>
Date: 13 Mar 91 06:03:33 GMT
References: <1267@soleil.UUCP>
Organization: Email Electronics, Melbourne, Australia.
Lines: 61

In article <1267@soleil.UUCP>, gopstein@helix.squibb.com (Rich Gopstein) writes:
> 
> I am going to build an interface to an OEM GPS receiver with RS-232
> output.   I would like to use an inexpensive multiline LCD display

Now this caught my interest ! How much does on OEM GPS receiver cost ??
Where are you buying from...etc (Note I'm in oz) ?
Any engineering samples you no longer require......(Now that's really hopeful)

> to show the status and current position textually (at least at first).
> I shouldn't need more than about 16x4 characters.

Others have answered this in some detail. I'm familier with Sharp and
Vikay modules which all (as has been mentioned) use tthe identical 14 pin
interface. WATCH OUT for the pin numbering however ! The pins nos are
numbered differently between module manufacturers, and not one of them
uses numbers which correspond to normal IDC headers !!

The grahics modules use a different Hitachi Chip (HD61830) which has the same
"Motorola" interface ..... they can even work in alpha mode similar to
the alpha only modules. Vikay also has another grahics module which uses
a different interface chip, and a more Z80 like interface.

You must adhere to the timing diagram for the "Motorola" like interface,
wrt the times b/w signal transitions.

I have heard (ie not experienced 1st hand) that the BUSY flag can be a
dodgy thing to rely upon. Apparently for some commands sometimes the
flag never gets unset. In your code you should either forget the BUSY
flag (which means you probably don't need to ever READ from the thing),
and use a timeout of at least 40uS, or at least have a timeout override
to waiting on BUSY. I don't use the BUSY flag.

There is a special sequence to follow on reset to ensure the module is
in a known state. Only some companies brochures actually mention it. Mail
me if interested.

> 
> How about a favorite CMOS microcontroller with RS-232 input?
> 

I've used Hitachi 64180 (very simple to implement the I/F with this
one due to E clock signal), Z80, Motorola 68HC05C8 and 8051 family
uP to talk to these. I currently use 'C' code for the interface.

	Good Luck
> Thanks.
> 
> --
> Rich Gopstein
> 
> gopstein@squibb.com
> rutgers!squibb.com!gopstein


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