This is great, Tony, thanks! I will try to find a handful of those
SAA5245 chips. I work primarily with PICs, so an I2C interface is
very handy for me. You rock.
-Dave
On August 27, Tony Duell wrote:
I forgot to answer an earlier message asking just what
the 3 chips were
that you could use to get video output from a microcontroller system
1) An SAA5243 (for the UK/Europe -- I think the 60Hz-vertical version is
the SAA5245) This is actually a teletext display IC for televisions, and
is controlled via an I2C bus (2 wires). The nice feature is that the
display memory can be read/written via the I2C bus, so it can be used as
a general-purpose video display. Actually, this chips is probably
discontinued, but there are more recent chips with the same features, and
anyway the SAA5243 is easy to get either from scrap TVs (the
Thomson/Ferguson ICC5 chassis, for example) or from TV spares places.
2) An 8K*8 static RAM, like a 6264
3) Some way of generating a 6MHz clock. A 74LS04 + a crystal, for example.
You might want to put some kind of buffer chip on the outputs of the
SAA5243 (I used a 74LS541 when I built something like this) which would
increase the chip count to 4 chips.
The I2C bus needs 2 lines from the microcontroller (clock and data). Each
line should be capable of being driven as an open-collector output, and
read as an input. The port lines on a PIC are fine. You don't need access
to the microcontroller bus.
You get a 40*25 text display (upper and lower case) with teletext-style
block graphics and serial colour attributes. Not bad for 3 chips and 2
port lines.
There was an article on doing this in Datafile (HPCC (UK HP calculator
user club) journal) in 1998/1999 (either the last issue of 1998 or the
first issue of 1999 I think).
-tony
--
Dave McGuire
Laurel, MD