multiple processes on PIC 16f690

I need to run two 5 digit 7-segment LED displays off a 16f690, which will display a number entered on a matrix keypad.

What I am not sure about is how to keep the display lit while data entry is taking place. If I have my display methodology correct, I will have 17 outputs to drive the display (segments a thru f and digits 1 thru 10) so basically, only one diit is really lit at a time, cycling through the ten digits fast enough should create the perception of having all digits lit at the same time.

That seems OK in my head, but when a key is pressed, the program will jump to the key entry routine... how do I keep the display routing running at the same time?

I have looked at the MAX7221, and I'm sure it would be a better option, but I would like to try do this without a driver to keep costs down.

Am I going about this all wrong?

Neill.

Generally a simple timer overflow IRQ routine will do the trick. Lots of sample code on the net. I've got some code for this in the Dragonfly kit documentation on my site.
**broken link removed**

You should use timer based interrupt code to update or "scan" your display hardware. The interrupt code can also easily detect and debounce your input switches and set flags for MAIN that indicate "new" switch presses.

Mike