My design makes use of demultiplexer (Demux).
It is as below:
First, I simulate with 4 leds (4 switchs accompanied)
I has design the 1Hz oscilator (by using Timer IC 555).
I has design the modulo-4 counter (2 bits: from 00 to 11 and return)
The outputs of the counter is connected to 2 control pins of DEMUX (to select channel).
If no switch changes its status from OFF to ON, this counter counts as usual (00,01,10,11,00,....)
But if for example, switch 2 is changed from OFF to ON, the status 01 is neglected and the counter have to count as follow: 00,10,11,00. But I don’t know to to control the counter pass over the status 01 to jump from 00 to 10. It seems a difficult task to me. And I’m now continueing to find solution to this problem since I think this is a possible idea to finish this assignment.
I really need your help!
ps. I'm not good at english (since I'm living in non-English speaking country). If there are some things that you do not understand, plz tell me and I'll try to express it again in English!