Digital system counters and karnaugh maps

[Peasha]

Can anyone assist me in designing a counter with the sequence 2907 using IC gates? Thanks

 

[schmitt trigger]

You mean 2-->9-->0-->7-->repeat
meaning in binary, an output of 0010, 1001, 0000, 0111, repeat?
And skip all other output codes?

 

[ronsimpson]

You mean 2-->9-->0-->7-->repeat

If this is ture:
2,9,0,7,repeat

You need 4 DFFs and some logic. (DFF is a data flip flop)
The logic look at the output of the FF and inputs a different number into the input of the FFs.
Logic: if 2 than 9, if 9 then 0, if 0 then 7, if 7 then 2.
>>only problem is that counter sometimes will not start up or gets locked and will not count.
Logic2: I would do it this way.
if 2 than 9, if 9 then 0, if 0 then 7, if (none of the above) then 2.
The improvement is that if the counter powered up with a 5 and the logic did not know what to do it might latch up.
Also if you are only looking for 2 or 9 or 0 then you are only looking for 3 states not 4. Might take less parts.

 

[schmitt trigger]

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