What is the best signal interface for PC ?

[_q12x_]

so... what you are saying... to link directly the counter 7493 to this memory chip and increment each of it's data stored inside ? Like this?
And 74138 decoder is not needed at all in this case, right?
And from D0-D7 of this memory might be the outputs to link to the matrix... right?

 

[marconi]

That is largely correct. You still need the 74138 to switch the columns on in turn when driven by the same 1, 2, 4 outputs of the 7493. You could construct some combinational logic but that would be long winded.

Of course you could do the work of the 74138 and the eeprom in software and then feed the 5 bit 'one of 5' column word and the 7 bit row/line data word to the 16 bit outputs of the MCP23017. You then connect these outputs to the circuitry you have designed in proteus.

 

[_q12x_]

Good news:
Memory #1
I figured out how to manually program a (simpler) RAM in my simulator, thanks to youtube and a couple of google searches, staying late last night. This was the easiest.
The most important thing for me, is repetition. If I am not repeating some new stuff enough multiple times, I forget it's head and its end in a very short time. If I make it a routine, for awhile, it is impregnating in my brain and I hardly forget it. I moved relatively quickly with these RAM chips now, because I did these things some years ago, once or twice, but not doing it again consistently or repeatedly, I forget everything. Well, something remained because I moved and recognized relatively easy now what to concentrate over and I work it out somewhat fast. But I helped myself from youtube as I said. Im happy I managed to make it work in the end.
I still have problems writing and loading a *.bin or a *.hex file into the simulation chip. THe content of these files is a mystery for me. I dont think I ever did it like this. So this is brand new and very important to figure out. So far I had no luck. If anyone who is reading these things know how to do it, please advise me. I will ask on other forums as well.

 

[_q12x_]

Memory #2
This one was a bit tricky, and I had to look more closely into it's datasheet. And I managed to make it work. It has a bit more complicated way of MANUAL programming, I changed and play with those links there and you have to switch both of them to program and read the chip. Thats the conclusion I got it work.

 

[_q12x_]

Memory #3
This was a fail in implementation but I understood what it needs to make it work. It is by far the strangest RAM I ever encountered for manual programming.

this simulation didnt work because that pulse circuit didnt want to work at all, probably some program bug or a mistake I made but im blind to see it; so I probably have to make a 555 circuit for it. And if that doesnt work, at least I tried. Heh. Its not the circuit fault its the simulator fault this time. Sometimes I personally get SF issues from programs, because I dont know each detail of the behavior of the program. Oh well....

 

[_q12x_]

All that was last night.
But from now on, like I said and I am repeating for clarity, I have to concentrate on loading a *.bin or a *.hex file into the simulation chip. The content of these files is a mystery for me. So this is brand new and very important to figure out. So far I had no luck. If anyone who is reading these things know how to do it, please advise me. I will ask on other forums as well.
So this is the next step I will concentrate from now.
Pretty hard if you ask me.... hard to figure out how to make it work.

 

[marconi]

How are you generating the program pulse which must be more than 45 but less than 55 mS?

 

[_q12x_]

I explained this already:
I tried this circuit but for some reason Proteus simulator didnt like it and didnt run it. The capacitor didnt charged up. I will have to try with a 555 circuit, replacing this simpler one.

 

[marconi]

Try this simple circuit with R as 1kR and C as 50 microF

Or R as 5kR and C as 10micF.

In both cases time constant t = R x C = 50mS

If negative pulse required then use simple circuit below. If positive pulse required then invert using transistor or NOT logic gate.

 

[marconi]

I explained this already:
I tried this circuit but for some reason Proteus simulator didnt like it and didnt run it. The capacitor didnt charged up. I will have to try with a 555 circuit, replacing this simpler one.
View attachment 100972

This circuit will not produce the required pulse shape and duration. I do not have time right now to explain why. It is to do with how the push button is wired in and RC time constant is only 10mS = 1KR x 10micF which is less than minimum 45mS.

 

[_q12x_]

nope , not good. I tested in other simulator that circuit with the transistor, which very much resembles your much simpler version and I applaud its simplicity, I like it very much actually, more than mine.
But the problem with both circuits here is that Pressed button !!! As long as I am keeping it pressed, it will "count" 0V ! Which is not good. So if im counting 10s with the button pressed down to 0V, the circuit will stay to 0V 10s. WHen I release the button, it will count another extra 50ms based on the cap and res values that I chose and reach 5V. So this behavior is NO BUENO !
What I really need is like this: Press ONCE the button and keep it pressed. But the circuit will not stay at 0V. It will jump from 5V to 0V in the moment the button made the contact, count internally those 50ms, and rise up to 5V by itself, while my button is still pressed. When I release the button from its contacts, the circuit still remains at 5V, unchanged. Only when I press the button again. and at the very first contact , the whole logic repeats again. Clear now?
I am trusting the good old 555 timer to do it. But... I didnt actually stay down to think about it. I only figure out how the logic should be, the one I just described so far.
Remember this is waaaay a SIDE mini-project or dare. Haha. Not at all the main quest Im in. Its a cute side quest. A curiosity.

 

[marconi]

Please draw me the circuit you have connected to the CEbar pin.

 

[_q12x_]

Good day sir, Mister @marconi and others that are reading my thread, please read this page --HERE-- I put it in discussion last night but unfortunately the guys that are answering me are too undecided. Usually they are of great help but here, in this case, this specific subject is like a black cat for them. They keep some inexplicable distance.
Its not that long, is 1page and a half of reading, until that big blue screen screenshot of mine. And you can skip many unimportant points. See if it is ringing a bell for you and help me progress and push this "programming a RAM chip with an external file" to its final conclusion.
Thank you in advance!

 

[_q12x_]

Please draw me the circuit you have connected to the CEbar pin.

you mean this one? Yours is better ! ...but both inutilizable.
we must think on another BETTER circuit. This is NO BUENO.

 

[marconi]

Please answer my question. SHow me exactly how you modelled my circuit and actually connected it to CEbar. Did you pass the pulse from my circuit through those relay contacts ? Did you do as in the attachment?

S1 is is NO pushbutton for programming. S2 is the NO switch to tell the chip to operate as a RAM ie programming over. When in programming mode S2 must be open. You know already what to do with the OEbar pin for programming mode and RAM mode.

 

[_q12x_]

This is the last circuit I made following your instructions.
I am now pretty sure how to connect the RAM chip in the next stage. No worries.
I made some very interesting advancements from 2 days in a row until today, about how to manually program a RAM. I start to get it, and also how to program a RAM from a file, which is very important.
I did not used the RAM or any relay in this last circuit. That RAM is floating there.

 

[marconi]

Have you run this circuit in proteus?

 

[_q12x_]

Have you run this circuit in proteus?

yes

 

[marconi]

I deserve better than ‘yes’.

 

[_q12x_]

I deserve better than ‘yes’.

Check my answer in #93 ...also your immediate answer next in #94
I was completely concentrated these last 2 days, full days actually, on the loading an external file into the RAM in Proteus simulator and tonight, some minutes ago we reach the salvation conclusion. Now I can load any external file as long it is not very complicated because the editor is very old and is not that nice to edit with it, but it is doing an excellent job, and that is all that matters. I will still have to research into more modern .bin editors, so there is more to push. We have progress.