up down counter freezes at 9

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schwach

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I was finally able to make an 1 bit up down counter but may problems is that when I reach 9 and fed in the up clock using the push button the display should still be 9 but it keeps looping back to 0. The same problems occurs when the display is 0 and I fed in the down clock. Any suggestion on how to fix the problem?

Here's a picture of the circuit I made, the supply and ground is the only part cut out from the pic

 

One way is to use the Parallel load option of the 192, reload with a '9', when '0' is detected

E
 
schwach said:
I tried using a /PL load '9' it doesn't loop to '0' anymore but now I can't count down
.
Click to expand...

The /PL has to be a pulse Low when loading the '9' ,,, at other times it must be High.

Repost you circuit showing how you have connected the /PL pin.

E
 
hi,
So that I am understanding your requirement correctly, do you want this....

Power on = display '0'

when counting UP 1 press = '1' displayed then so on until '9' ,,, the on the next press display '1'.???

when counting DOWN, say starting at '1', the next press displays '9'.??

so UP is 1,2,....9, 1, 2...9

DOWN is 1,9, 8 ..... 1, 9, 8

E
 
The requirement is

power on then clear so that display = "0"
when counting UP press a button so that UP is from 0,1,2,.....,9 only and not looping from 0,1,2....,9,0,1,2,...9
and when I want to count DOWN press another button so that count will go, for example from 5,4,3,....,1,0 only again not looping from 3,2,1,0,9,8,7
 
schwach said:
I tried using a /PL load '9' it doesn't loop to '0' anymore but now I can't count down
.
Click to expand...

Hi,
You dont want to detect '9' in that way, because when you detect the '9' count it will load '9', so it will freeze on '9'.

Consider the count after '9' when counting UP , make it load '1'

when counting Down consider detecting '0' and Load a '1'

Have a look at the TCount up and down pins, they will help you.

E
 

I see what you are asking,, I thought you were asking for a looping counter [ which is a common requirement]

So its 0 to 9 on UP presses and then it waits at '9' for DOWN presses until '0' then it waits at '0' for UP's

Have a look at the TCount up and down pins, they will help you.


E
 
schwach said:
What do I need to do with the TCount up and down pins?
Click to expand...

hi,

The Tcup will go Low at a count of '9' ,, the Tcdn will go Low at a count of '0'

If you used the Tcup and Tcdn to control the Output state of a Bistable IC, for example a 4013 [ or equivalent HC bistable type ], then use the Bistable outputs to enable/disable Gating logic of the the Up and Down clocks to the 192.

Remember that for either the Up clock or Down clock to count the 192, the non counting clock input must be held High.

E.
 
I'm sorry fors asking again, but how do I connect the Tcup and Tcdn? I tried connecting the Tcup to pin 5(D1) of the 4013IC and pin 1(Q1) to the up clock of the BCD up/down counter and pin 3 (clock) of the 4013 to one of the output of the 555 timer. Is this correct?
 

hi,
I can see your problem.

As you want to Up count from 0 to 9 and then ignore any further Up counts, it waits for Down counts and counts down from 9 to 0 and then ignores any further down counts.

If the counter is say '5' it will either count Down or Up depending upon the switch pressed.

The problem is the TCup occurs at the 9th count on falling edge of the clock pulse and lasts for the duration of the Low of the clock pulse.

So as the Up clock rises to a High [ which it has to be for the the Down clock to be Enabled] the counter steps onto '0'. Then you get the TCdn low pulse.

I will run some LTSpice sims and see if I can suggest a solution.

E
 
hi,
Look at this option, it works in simulation OK.

Note for testing I have clocked the Up and down 12 times to show that it ignores greater than '9' less than '0'

I use a CD4002 as I do not have a 4 input NOR model in my LTSpice.

E
 

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