Date   : Fri, 31 Jul 2009 17:52:20 +0100
From   : philpem@... (Philip Pemberton)
Subject: Ground Control "UTA" teletext adapter -- technical

Mark Usher wrote:
>  
>> Has anyone here written code to drive the UTA? If so, I could really
>> use
>> some hints (example code or annotated I2C traces would be even more
>> useful) on how to initialise the tuner and tune to a given channel
>> frequency...
>>
>> I figured if all else fails, I might be able to use the UTA as a signal
>> source for my TTX receiver project. This, of course, depends on the
>> quality of the video output signal and whether it's good enough to use
>> with an external decoder.
> 
> That's easier than dragging the RISC PC out of the loft? :-)

Aye...

1) I have no idea where the mouse and keyboard for the RiscPC are. Or at 
the very least a PS/2 mouse and the PS2MouseMini adapter (which is 
probably plugged into the end of the mouse I last used with the RPC, and 
$DEITY knows where that is).
2) I'd have to find room for, acquire and set up a second monitor (I 
don't have any spare KVM plugs)
3) It's buried deep within the loft. In its own cardboard box, under 
about half a dozen other cardboard boxes. Getting to it would involve 
hiring a skip.
4) As far as programming projects go, "make the UTA work on something 
more modern than a 1996-edition Acorn RiscPC600" is a pretty good one.

Also, the Euro CCT (SAA5240) appears to have a "don't care" function, 
i.e. it just grabs every page as it comes. That might allow me to avoid 
building a whole Teletext acquisition system -- assuming the Teletext 
page rate is low enough (I seem to recall calculating the max rate to be 
somewhere around 0.5secs/page) and the EuroCCT can send data over the 
I2C bus quickly enough.

Just seems like a fun side-project... :)

Unfortunately the SAA5240 datasheet is full of remarks like "For further 
information, contact the Applications Department, Philips Semiconductors 
UK" or "For further details, see the SAA5240 User's Guide". The latter 
document seems to be unavailable... time for a bit of guesswork, it seems :)

-- 
Phil.
philpem@...          
http://www.philpem.me.uk/