Getting a false count on a PIC circuit driving cascaded 4029 and 4511

Thread Starter

MrsSTechnology

Joined Feb 8, 2015
4
Really hope someone can help me!

I have a GENIE PIC circuit that I am using to create an up/down counter for a scoreboard. Pretty simple program and all is working well except when the first pulse goes to the 4029s the second chip is also getting a pulse so the first output reads '11' instead of '01' on the 2 7 seg displays (common cathode). This then delays the second chips could so the 10s unit is 1 out throughout the count so '19, 10, 21...'

I have tried a few configs including adding an OR Gate from the clock and carry out of the first chip to the enable of the second. It looks like the rising edge of that first pulse is the culprit.

Has anyone else had this problem? Any solutions you can offer? I have studies the 4029 data sheet and am truly stumped.

TIA!!
 

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Thread Starter

MrsSTechnology

Joined Feb 8, 2015
4
Hi Eric
Thanks so much. I had tried that and found that I now get no cascading pulse at all with the OR gate. Am I missing something? (see updated attached)Wondering if it is a connection to the 4511?
Any help is greatly appreciated. This has been a head scratcher for 2 weeks now :(
L
 

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Thread Starter

MrsSTechnology

Joined Feb 8, 2015
4
hi,
Look at this clip from the 4029 d/s for cascading devices.
E
Also, I had found a thread that you did about 4 years ago that started out with someone having the same problem (which spiralled into a massive circuit using optical switches and the likes. Nightmare!) I noticed at the end of that thread that someone mentioned that the simulation software might be the problem. I would hope that four years later New Wave would have figured this out but perhaps not. I did everything you instructed (I think :oops:) and am getting the same outcome. I will breadboard the circuit and see if it has the same problem too.

Thanks so much for your help. It is for a student of mine and I am so frustrated not being able to help him. I'm a bit of a rookie too.;)

L
 

absf

Joined Dec 29, 2010
1,968
I simulated the circuit in proteus and it works fine counting 0.... 19,20,21,22 .....even without the OR gate. May be the problem is in the simulator. Is this GENIE PIC a real hardware or just a simulation file?

If I were to confirm this, I would try it out in real hardware. See my sim attached.

Allen

p/s I noticed the CO of the second 4029 is connected to Vdd. I think it should be left open.
MRSTECHNOLOGY.PNG
 

ScottWang

Joined Aug 23, 2012
7,305
I simulated the circuit in proteus and it works fine counting 0.... 19,20,21,22 .....even without the OR gate. May be the problem is in the simulator. Is this GENIE PIC a real hardware or just a simulation file?

If I were to confirm this, I would try it out in real hardware. See my sim attached.

Allen

p/s I noticed the CO of the second 4029 is connected to Vdd. I think it should be left open.
View attachment 80166
If the clk key is a push button then in the real world we have to considering the key debounce circuit.
 
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