counter limiting circuit problems !!

[zerody]

Hi, my circuit is suppose to count up till 7 and count down to 0. However,my counting keep count down at 8, I need some help in this. Thank you.

 

[chuckey]

Looking at your circuit , its meant to count up to N then back down again?. One problem I can see is that U5 (AND) is inhibited by the 0 from the switch, so its output is always a 0, so the output of U9 is also always a 0 because it always has a 0 on a input (from U5). Use exclusive OR gate at this point.
Frank

 

[zerody]

hi, I'm not sure what you meant by N, but it's suppose to count to number 7 and count down to 0, will try replacing my U5 when I reach home, thanks for helping

 

[zerody]

Looking at your circuit , its meant to count up to N then back down again?. One problem I can see is that U5 (AND) is inhibited by the 0 from the switch, so its output is always a 0, so the output of U9 is also always a 0 because it always has a 0 on a input (from U5). Use exclusive OR gate at this point.
Frank

I tried replacing the U5 with exclusive or but it count up to 2 instead then it count down.

 

[chuckey]

N is the number set by the switches. Try setting the switches to all the possibilities of numbers and then log the actual numbers the counter runs up to.
Frank