Multiplexed user interface ideas

[Pferd]

Hey there,

I am in need of some clever help with my user interface. It consists of 5 seven segment displays plus a 2x8 button array with illuminated tactile switches. The Leds are on two channels each 8 just like the seven segments plus dot. The channels get multiplexed by a 4017 counter and BC517 Darlingtons. The low side is driven by a ULN2803. But I am struggling with the switches. Maybe somebody has a good and elegant way of wiring them up. Ideal would be, since this interface sits on a separate daughter-board, to utilize the same 8 lines the leds are using for the switches during the time the two switch-channels are active in the cycle. The last option as far as I can see is to use a whole separate port (PORTC) for the switches. In my schematic the 16pin connectors are meant to be together and the 10pin connectors are together.
I wouldn´t mind using the PORTC for the switches, since I have many pins left, but I´m just wondering if there is a more elegant solution. But I can´t see a way of using only one port for the leds and switches without disrupting the led action.

Thanks in advance!

[Kleinstein]

If only 1 key at a time (one of each group) is pressed, one could connect the switches to the segment lines and use to seprate inputs for the µC. In an additional phase the µC would turn of all leds on the high side and than scan the 8 low sides 1 at a time.