AT28C16 EEPROM with 5x7 led matrix Project

Thread Starter

q12x

Joined Sep 25, 2015
1,410
I still have to figure what is the problem with the 7493 circuit - why is not counting binary but randomly ?
It may be damaged? Is one of the thoughts that crossed my mind.
1663587250438.png
 

Thread Starter

q12x

Joined Sep 25, 2015
1,410
I built separately another circuit for 7493, (that counts to it's maximum 16 beat's)
1663591356209.png
with the same IC as before ,but also with another brand new, and I got the same random result, so the IC is good.
I also replace that big button with a brand New button and again, some slight improvement, But still not good enough.
I built in the movie, a button debouncer using 470nF, After movie, I switch to a 10uF and now to a 200uF. The difference is visible and better but still not good enough. I believe I might have to make a button debouncer using a 555.
I strongly believe is the button fault.
 

Thread Starter

q12x

Joined Sep 25, 2015
1,410
What is your button contact filter circuit.?
Please check the small video segment here:
And later, after that 470nF I replace it with a 10uF and even with a 200uF. With this last C, I start to see very good improvement and the circuit was starting to actually make some sense, I can visibly see counting in binary but still, skipping from time to time, so this is how I deduce its the blody button.
 

ericgibbs

Joined Jan 29, 2010
16,370
hi q12,
This simulates the action of a Schmitt IC.
The pulse input is slow rising, so an ordinary gate could produce multi clock pulses.
The Schmitt produces sharp pulse edges
E
 

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Thread Starter

q12x

Joined Sep 25, 2015
1,410
Look at my post #7.
You mean the link in your post. I read it all. Its a good read. 3 ways to do it.
But I was thinking on a opamp in all this time, and hop you jumped in with that page of yours and confirmed my assumption.
And I do know what Schmitt means but I didnt use it that often. Im not even sure I have an IC for a Schmitt. I know I have 1 or 2 logic gates IC's that includes Schmitt in them.... but that is another story.
For the moment, this is the circuit I choosed already using my favorite IC, the 555 who resolves everything.
1663594837614.png
Which circuit did you build in real life on the breadboard?
I left aside for the momment the SRAM... I know. But I will come back to it immediately after I finish with this EEPROM.
I am now concentrating on an at28c16 EEPROM that just arrived from a friend from England to play/test with it. I will have to make a 5x7 led matrix display some letters in the end. Thats the plan. So now, Im starting THAT circuit. And fix at the begining of it, a big hole that I fall in. But I am climbing up, no problem. I didnt expect these bumps on the road. But is fine, I did some of this stuff before, but now is integrated in a bigger picture.
Thanks for asking !
 

dl324

Joined Mar 30, 2015
15,113
And as I started, I got into some problems:
You are mixing CMOS and TTL logic. Beginners shouldn't do that because TTL output levels aren't guaranteed to drive CMOS inputs. It will work for typical TTL devices, but not all devices will be typical.

Post a schematic with the full part numbers so we can see where you might have problems mixing TTL and CMOS.

It's also not a good idea to use asynchronous counters when you're decoding the outputs to drive other logic. Multiple bits switching at the same time can cause problems. I went through the output transitions on the binary counter and didn't see any issues with the way you're decoding 7.
 

Thread Starter

q12x

Joined Sep 25, 2015
1,410
And it worked.... what a day. Now is clearly executing a crystal clear button press without any kind of monkey bizniz, like before.
But my 7493 is now counting to 3 !!! instead of 7. I know in the simulation worked just fine... I have to recheck the save file now. Very strange. I hope is a misplaced wire somewhere.
 

Thread Starter

q12x

Joined Sep 25, 2015
1,410
Simulations don't always reflect reality.
Yes, quite right, hmmm... I know I dont make stupid mistakes anymore... I am folowing my circuits quite exactly.
I just checked the simulation and indeed it is counting fine to 7.
So it must be some other detail that the simulation is overlooking, presuming that you "know" it before hand.
I don't see a pull up resistor on the CP0 input. I assume that the red wire on the switch is connected to ground.
the red wire on the switch is to +5V and the Black wire is to gnd. The Green wire of the switch is to CKA.
7493 pinout.jpg
Should I put a pull up resistor on CKA (your/CP0) ?
 

Thread Starter

q12x

Joined Sep 25, 2015
1,410
Here is the 'deal' working !
2 problems resolved ! Again...what a day.
I sincerely belive this will be quick and easy, but NOOOOOOHOOOOOHOHOHOOOOO
 

dl324

Joined Mar 30, 2015
15,113
the red wire on the switch is to +5V and the Black wire is to gnd.
On the breadboards you're using, it would be logical for the blue busses to be ground and the red busses to be power. You did that on the left power rails, but not on the right.

Are you handling the CMOS integrated circuits properly (i.e. ESD safe manner)?
 

Thread Starter

q12x

Joined Sep 25, 2015
1,410
Not really...
On the breadboards you're using, it would be logical for the blue busses to be ground and the red busses to be power. You did that on the left power rails, but not on the right.
Yes only on the right side I inverted the rails because is how I work, is easier to use in both sides of the chip the same color and length of a wire for the same polarity - either is pos or neg.
Are you handling the CMOS integrated circuits properly (i.e. ESD safe manner)?
No. Which are the CMOS again? The 7000 series I presume?
 
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