Digital circuit help

[kosoniscs]

I've made a board which has four 7seg. displays multiplexed. They are connected at the same bus and a PIC controls the turn on and off time of each one of them. The problem is that, in Brazil, PIC is not so cheap and I would like to use a digital circuit to make it. The project is kind of a counter so that, it is not necessary to use a microcontroler. All I need to do is connect four different counters in the same bus. Can anybody help me with suggestions or circuits that could make it?
Another doubt that I have is about the noise caused by the mechanical contact of the buttom. Using a microcontroler I know how to 'don't see' the noise. How can I do this kind of thing using CMOS counter? Is there an ic that do this?
Thanks

 

[surajbarkale]

Search the term 'Switch Debounce' & you will get hardware schmatic for it. As for the counting task check out http://www.ee.washington.edu/stores/DataSheets/cd4000/74c926.pdf but I fear it would turn out more expensive than PIC.
P.S. Check out AVR or 89C2051/89C51 they are cheaper than PIC.

 

[kosoniscs]

Thanks...
Actually I need two independent counters that will use two displays...I'm looking at fairchild site at this moment to see if they have what I need. You know could you tell me?
Thanks again

 

[surajbarkale]

Check out CD4033 it has internal counter & 7 segment decoder. You can use 74hc244 to interface it with a bus.
But the discrete logic makes it cumbursome to mux display lines (you need too many IC's). And eventually cost of all IC's will equal a microcontroller. ;D