Teletext Decoders
David Sh4mir Moto Semiconductor Israel
like to feed the characters into a computer port, and then process them
accordingly.
Any help would be appreciated,
Arie Markus 4X6JO / VE3JLM
Direct replies would be appreciated
reply to ar...@msil.sps.mot.com
l.gud...@uws.edu.au
n...@oakhill.sps.mot.com (David Sh4mir Moto Semiconductor Israel) writes:
>I am interested in making a decoder for Tele - Text, I would
>like to feed the characters into a computer port, and then process them
>accordingly.
>
>Any help would be appreciated,
>
>Arie Markus 4X6JO / VE3JLM
>
Post the replys please as some others my be interested
|----------------------------------------------------------------------|
| Lars Gudiksen (Senior Technical Officer - Hardware Suuport Group) |
| |
| Teaching and Services Computing Center |
| University of Western Sydney - Macarthur |
| New South Wales, Australia |
| |
| Email l.gud...@uws.edu.au Ph (61-46) 203 259 Fax (61-46) 266 937 |
|----------------------------------------------------------------------|
Tony Duell
Well, I'm not sure how much of this applies to the rest of the world (non
50Hz,PAL, 625 line), but I'll post anyway, figuring that someone may be
interested.
Philips (Data Book 4 part 12) list a number of 'Computer Controlled
Teletext IC's' -
The SAA5243 is a 625 line tletext decoder, controllable through the I2C
bus. There are 4 versions for different language character sets. The
application circuit uses it, an SAA5231 video input processor (handles
Clock recovery etc) and an 8K*8 static RAM (6264 I guess).
The SAA5245 apears to be a 525 line version for USA
( Aplication circuit is similar)
The SAA9041 is a teletext dcoder for all formats using dynamic ram as
storage.
To get I2C from your computer, there is a Philips IC PCF8584. It looks
like an I/O port to the CPU, and can interface to 8086 or 68000 buses.
There was a IBM-PC board using it described ion Elektor a couple of months
back - I built it - works fine.
I may get round to desinging a teletext decoder round these IC's one day.
- if so, I'll get the details to the net somehow. (BTW, on the SAA5243,
and probably the others), you can read the teletext page throught the I2C
port.
-tony 'PDP11 Hacker' Duell
a...@siva.bris.ac.uk
Mark Savenije
It's really quite simple if you can buy the right IC's. Philips makes them
all. I don't have the partnumbers here, they are at home. You can find
descriptions and sample schematics in the IIC databooks of Philips. You'll
need a videoprocessorchip, teletextprocessorchip, RAM-chips, and a
"IIC to parallel"-chip and a few other components. I expect some other
companies will produce the same components. BTW, You can buy cards for PC's
with a complete tele-text decoder and additional software. Don't ignore the
software that is needed to get the right pages and for the communication
between the tele-text decoder and the computer.
If you really want to know the partnumbers, or a copy of the schematics, let
me know,
Mark Savenije, Department of Computer Science, Utrecht University,
Padualaan 14, P.O. Box 80.089, 3508 TB Utrecht, The Netherlands.
E-mail: mar...@cs.ruu.nl, Phone:+31-30-533385, Fax:+31-30-513791
Mika R Iisakkila
>Well, I'm not sure how much of this applies to the rest of the world (non
>50Hz,PAL, 625 line), but I'll post anyway, figuring that someone may be
>interested.
Me too. Elektor Electronics published a PC controlled Teletext decoder
project a while back (part 2 was in Jan 91 issue). The same project
appeared in the German magazine Elv. They have it in kit form as well.
It has capabilities to superimpose the text on top of composite video,
which adds some complexity, but otherwise it is a rather generic
application of the Philips chip set. It works OK - too bad that the
software is lousy and they don't give enough details to write a better
one yourself, so you'll need to get the Philips data book.
The chips may be a bit hard to come by. If everything else fails, try
your local TV service - they probably won't sell them separately, but
buy the cheapest decoder add-on for any TV set (of course check that
it has the right chips first). They're not very expensive these days.
This way you'll get the surprisingly hard-to-find 13.875 MHz chrystal
too.
--
Segmented Memory Helps Structure Software
Colum Mylod
has messages in German, English ("Ready"), French & Italian, but on Turkish
it sticks to English. It seems this can be set per page - on Lifestyle ch.
several pages are in differing languages and the decoder switches appropiately.
Are the messages held in the decoder but selected by the broadcaster (my guess),
or can the broadcaster send the text?
Post of e-mail replies, I'll summarize if any interest is expressed.
Paul Simmonds
Feb 1992 Electronics & Wirless World (was Wireless World) has a Teletext
to Serial Board Project, complete with PCB & ROM available. Wirless World
should be available world wide from good (technical) librarys.
Paul Simmonds (p...@jet.uk)
- Disclaimer: Please note that the above is a personal view and should not
be construed as an official comment from the JET project.
Koos van den Hout
> In article <1992Jun1.1...@oakhill.sps.mot.com>
> n...@oakhill.sps.mot.com (David Sh4mir Moto Semiconductor Israel) writes:
>
> >I am interested in making a decoder for Tele - Text, I would
> >like to feed the characters into a computer port, and then process them
> >accordingly.
> >
> >Any help would be appreciated,
I have a teletext decoder plugged in to my PC. It's a complete teletext decoder
from Video signal to teletext using some teletext chipset.
I don't know if this is exactly what you are looking for, but I got it from
'Keyword Info Systems', Delft, +31-15-624940.
You get it with software, sources and techref complete.
Grtx. KH
| Koos van den Hout (ko...@kzdoos.hacktic.nl)
| BBS Koos z'n Doos : +31-3402-36647
Mika R Iisakkila
>How exactly is language specifed in the teletext standard? My TV (Grundig)
>has messages in German, English ("Ready"), French & Italian, but on Turkish
>it sticks to English. It seems this can be set per page - on Lifestyle ch.
>several pages are in differing languages and the decoder switches appropiately.
There are 3 control bits reserved for this purpose in the header row
of each page. These select the character set that should be used to
display the page. As far as I know, only 6 combinations are generally
used (English, German, Swedish, Italian, French and Spanish). Philips
makes some special chips with all kinds of weird character sets, like
Hebrew and Arabic. The latest Teletext standard probably allows for
more character sets in extension packets, but I can't tell more about
them because I haven't been able to get the specs (if someone has,
please let me know where you got them).
>Are the messages held in the decoder but selected by the broadcaster (my guess),
>or can the broadcaster send the text?
If I understand you right, you're referring to some messages that the
TV displays when you're fiddling with the remote controller. These are
generated by the TV set itself, but the TV probably uses the character
set bits of the current teletext page to select the language for the
messages. Would be a typical Grundig feature.
David Dix
was designed and built by a local company in 1987/88 and sold locally.
I use one of these connected to my bbs system to provide teletext pages
as part of the bbs service.
The decoder circuit uses SAA5230 (video input processor?), SAA5240P/A
(625line teletext decoder?), an 8k static ram TC5565PL-15, an Intel
8751H-8 cpu (provides rs232 interface), a CITAC SAB3036, TDA 3541, and
a few other discrete components. One of these is identified as a SAW
SW174A. There is a metal enclosed VHF demodulator.
The whole thing is asseimbled on a sigle sided pcb with a neat toroidal
transformer based psu all in a slimline box that just looks like a rather
large modem :-)
On rear panel there is aerial connector, 25way D socket for rs232 interface,
reset button, fuse and power in cables.
I believe it comes with some management software written in pascal (for DOS)
I also have C programs for Unix for this device.
If anyone is interested the company details are:
INVISION Enterprises Ltd,
MacEwan Wilkinson Kerkhof Ltd
PO Box 62-006
Sylvia Park
Auckland
New Zealand
Phone +64 9 579 1556
Fax +64 9 634 0980
Sorry, no idea what the things cost or their availability :-)
Disclaimer: I don't work for or otherwise deal with this company except that
I'm a happy user of one of their products :-)
*
d...@kcbbs.gen.nz (David Dix) ZL1UZC
Kappa Crucis Unix BBS, Auckland, New Zealand k * *
Ph. +64 9 817 3725/3714/3094 v32bis/v42bis .
Fidonet 3:772/90.0
*