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!