thanks for the input guys, I found I had left a temporary test routine in the code, and when I rectified that, voila ! tons of time to do the whole lookup table in the main loop with no problems, I even put the BCD address decoder in too.
I feed the 4 data bits from a Holtek HT12 rf link in to 4 pins, and the valid transmission pin to another.
I am only using 2 of the SPI pins, the MOSI and the srclck , the latching is done externally to the micro which is how I sync everything.
I just have to make sure the data is all clocked into the SIPO before the end of each 15th line.
I want to integrate the HT12 decoder into the project too, but can't get the library to run, ( http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1289382492/8#8
) so I use an external HT12 chip, I would like to try and get it on the micro....
The trick to get the nice horizontal resolution synced to the HD video, is to load 16 bits into a SIPO ( 2 x 595 I am using ) during 15 lines of the video data, and then to latch at the next horiz flyback time, with the parallel outputs feeding a high speed 16 bit PISO , which is loaded and read every line ( clocked by a 4 Mhz oscillator )
This gives basically 16 times the horiz resolution than trying to generate the video real time. I even made some nice fonts as opposed to the 7segment type numbers I had on the 74HC prototype.
Its similar to the teletext used on TV broadcasts ( do they still do that ? )
Its a big rats nest :-/ on a protoboard at the moment, but I will post some details and pics when I get it done.