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.