What is the best signal interface for PC ?

- I am a bit 'new' to using self alone ADC's; ... I used it as integrated function of a PIC, I read about it, I have a general idea as one does, but using it as a stand alone chip, I Never. So...forgive me if I was a bit hasty or jumpy or stupid when encounter NEW concepts like this. For me this is a new territory. Very interesting territory actually that I will get into more depth... but it remains in a todo list. Not right now. Right now I am putting on the table the cards that I consider important. So... I get into digging on wikipedia and I opened 3 pages: [Analog-to-digital converter], that lead me to [Gray code]. And a 3rd one very new to me, I never heard of it [Flash ADC].
Mister @marconi here (I've almost write Tarcone, like a mafia boss name, haha, but you are not far from one, right? hahaha - little joke). You first introduced me to the [Gray code] concept actually in your last project which I avoid it since it was completely new to me. But you also give me the lecture about it, and I also read on wikipedia myself back then. But now, scrolling and reading lightly in ADC page, to refresh my memory about the principle, the rotary encoder using [Gray code] jumped on me, like that. And is excellent ! - This means, I will certainly build one and play with it. Again, not right now, now I am putting on the table what is important. Making some plans and speaking my mind. From my understanding, [Gray code] is exceptionally used for rotary encoders, where you get only one possible code all the time, whiteout uncertainty, while rotating between the values, or as wiki says more elegantly : "between two successive values differ in only one bit". I want to believe it can be adapted to a device that is not rotating like a potentiometer does, but something like a LDR or termistor. Very fascinating subject that remains to be dig in.
- Another interesting 'card' on the table, is future addons to my board. One addon that I will surely built immediately after I finish all these IO boards, for security reasons only, is a string of transistors for a safe and secure Output drive. I will probably use BD 139 because I already have 100pcs brand new. I will probably but unsure yet, I will build a string of mosfets but at this chapter, I only have very small, smd mosfets like my A09T , which is a N-Channel and possibly A19T which is a P-channel. But they are very small and not so powerful. My greater wish is to have more powerful mosfets than those, to drive some serious loads. It will probably remain to do it in time, in the future,when I will have access to such mosfets, but for sure, the next step I will add those BD139, because I have them and are powerful enough. I want more powerful than them , but like i said, in time. So this is my security plan for the Outputs only. Next, it will be the inputs, and that is a bit of a new territory for me, because I played way too little with inputs in general. This entire 100 IO's project, partially its big reason, is built for testing and learning all sorts of inputs. I hope I will get to that and soon enough.
Thank you for reading. Romania, end of communication. Haha

Ive researched some more and I found this one:

Now is a bit more reasonable price. But still high for 1 single chip... My limit to buy, is 1 or 2 of them.... instead of the usual 100. Aaah. But still, much better than the last one I find.
I really wish from all my hearth this website allowing me to edit my previeous posts, for a cleaner overall thread... like they do it on AAC forums. This is my research so far... and I also learned new things in this time. Very complicate subject this stand alone ADC chip. You have to be very smart on choosing the right thing. I found a number of ADC options, in some boards and on chips. Very complicated subject. Hmmmm...for now while im fresh in the middle of it.
If you find more cheaper than this, do tell me about it, keep in mind the shipping to add to the total sum as I pointed alredy in the screenshot I made.So that ADC0820CCN that I selected is actual total price is 2.6$ for 1 single chip. Still high price for me.
I am very serious on building a ---TEST--- ADC made from opams set as comparators, that I have a lot, and resistor voltage dividers. If you have a circuit diagram for a DIY ADC that you can recommend to me, please do so.
Thank you.

You can use the LM3914 which I think you have a few to be an ADC.

Interestingly this chip will produce an output which changes by only one bit between successive voltage intervals eg 00000, 00001, 00011, 00111, 01111, 11111.

marconi said:

You can use the LM3914 which I think you have a few to be an ADC.

Click to expand...

Wow, I never have of thought of using this chip ! Yes indeed I have a few more left. You just had a genius idea !!! Thank you. Im not sure what is the difference between LM3914 and a normal ADC. My very best guess, LM3914 will be a 3 bit ADC or something close to one. Ive seen on youtube a 3bit ADC made out of 7 opamps. I believe I am not wrong. I just searched and "a 10 bit ADC counts 0 to 1023" but I didnt find how many opamps has inside. I bet something like 200 opamps?, wild guessing.

Assuming the LM3914 has 5 outputs - it has more but for this explanation it does not matter - then the 5 bit word uniquely represents a voltage interval. By voltage interval I mean the the voltage levels at which the 5 bit word changes by one bit. So, if you wanted to measure an analogue voltage input in the range 0 to 10V, each voltage interval would be 2V since 10/5 = 2 where 10 is the voltage range and 5 is the number of code words ie 00000. 00001, 00011, etcetera.

Now you have 5 bit digital code word for each voltage threshold you can convert it into a binary or decimal number using combinational logic or a look up table using a Programmable Read Only Memory or using some software code.

I seem to remember you can connect LM3914s in cascade to cover a wider range of voltage or have more voltage intervals to increase the resolution of the conversion from analogue to digital.

• The first layer of wires is done for all, you can tell because the squares have a second longer bottom cardboard they are glued to.
• What Im showing here are the PADs - I worked literally 4 days on them. I had to take longer breaks because is so repetitive and so incredible boring doing it manually. Surprisingly, it was 'kind of' pleasant after you manage to enter in trance, in 'the flow'. Especially when you literally STOP thinking in perspective, in the future, when you STOP expecting total and full results, as our mind is tricking us so often, and concentrate on the damn job, piece by piece, pad by pad, 1 by 1, until you wake up from the trance and realized (after a good couple of hours, sometimes >5) that finally, 1 strip of pads is done. Aaaah, I cant explain in words what a relief is. Haha. Now, all 4 are finished. One big stage of the project is done.

marconi said:

Assuming the LM3914 has 5 outputs

Click to expand...

LM3914 has 10 Outputs.
LM3914 has 10 opamps inside, wired as comparators on a string of 1k resistors.

You are very right ! they can be cascaded to obtain a better resolution/fidelity of the variable analog input (sig at pin5). Very interesting line of thoughts, I like it.


I just searched for half an hour because I forget where I put them, and I count I have 8 of them left.
So yes, we are good for 2 or 3 mounted in cascade.
I start to realize that the best thing is to buy a 10bit(or higher) ADC, as expensive as it is per 1pcs.
It's small dimension beats everything and also I don't have to built them... this is my current thought.
Ideally, I wished to have 16 ADC, one for each pad on one of my square MCP23017 board. At least one full and complete. Hmmm.... Things start to get hairy at this point. But in the end, 1 or 2 expensive but good brand ADC will probably satisfy the curiosity, at least, in the begining. And is always room for upgrades later in the future. Nice is to have it good from the start, when Im cooking it now, but... Ill have to adapt to the contemporan capitalistic monetary situation.
On another way of view the situation, LM358 is already a dual opamp in one package, and I have 100smd and another 100DIP in my stock. Also they are very cheap. But is a ton of work if I have to get on this road, and I know it... But I am thinking, that 3bit ADC made from 7 opams, I can use 3xLM358 and one uA741 which I also have 100pcs as well. And voila, 7 opamps for a very shitty ADC but I will have 16 shitty ADC for each pad on 1-ONE MCP board at least.
Money, huh? In capitalism. It sucks. Thats why this project stagnated so long from my youth years, because capitalistic money... Damn. Eh well. All I wish right now is not having the worst idea ever and regret it later with the 3bit ADC.
To continue your idea, with the LM3914, I can use all 8 of them also as a 3bit ADC, using only 7 of its opamps... or all 10 opamps why not. It will be a tiny bit over 3bit in this case. But this means that 8 of them will serve for only half of my 16-I/O MCP board. Thats why I bring the idea of using the actual opamps, 7 of them to cover all 16 pads. My idea is an alternative. Its the same shitty 3bit resolution either way, haha.
Also, is good to mention:
with __3bit ADC we will have 2^3 = 8 steps resolution (using 7 opamp comparators)
with __8bit ADC we will have 2^8 = 256 steps resolution. (using 255 opamp comparators)
with 10bit ADC we will have 2^10 = 1028 steps resolution. (using 1027 opamp comparators)
with 24bit ADC we will have 2^24 = 16777216 steps resolution. (highest ADC ever built)
- Thank you for involvement !

I believe... it all comes down to:
A- Many and Bad (multe si proaste- its a saying in my language)
(Many because I have many opamps already and Bad because only 3bit resolution)
or
B- Few and Good
(Few because expensive and Good because 10bit resolution)
What are your thoughts? What you will do in my place?

I have a very funny idea, to use a single opamp for each pad of all my 8 MCP boards. So I have 128 pads in total, linked to 128 opamps and it will give me a gigantic big --- ADC ! Hahahaha. 128 steps resolution means 2^7. Just for the fun of it I suppose.

And the moment we all were expecting, all 8 boards are finished, tested and working.
I still have some small problems to resolve until the "final product", this right now is in test stage still.
I am very happy how it come out.
I've also made a movie about it:
Thank you.

Hello mister @marconi
I finally used your led matrix. Not as we originally intended but with interesting results.
I may say, it is a bit dificult component because it has some specific pins for positive and negative connections Aaaand it also has a inverted way of connecting as well. Interesting functionality but hard to pinpoint. It was hard for me because it is my first time with such a thing. The conclusion, it was a success and I am happy with the results. Even if it is a test or a game.
Here is a slight longer movie that I originally intended, with many-many points in it.
Thank you for watching and I will make those letters as we discussed in the beginning when you send me that led matrix.

See what happens to the circling led display as you speed up the scan rate. Does this give you a hint on how to use this display?

ps: I am pretty sure I sent you the data sheet for the 7 x 5 matrix. If I remember the LEDs are wired common cathode but do check this - in groups of 5 LEDs, one group to each of the 7 lines.

marconi said:

See what happens to the circling led display as you speed up the scan rate. Does this give you a hint on how to use this display?

ps: I am pretty sure I sent you the data sheet for the 7 x 5 matrix. If I remember the LEDs are wired common cathode but do check this - in groups of 5 LEDs, one group to each of the 7 lines.

Click to expand...

Oh, this is not new to me at all. I am very aware of cycling rapid times gives you the desired shape or character on the matrix. I know this from when I was 7 or 8 years old. Really, I read some interesting stuff at that age, but... you know, capitalism is keeping me down.
And yes you send me its datasheet, and I did use it but is having some weird circuit schematic inside that I could not use it in practice so I had to re-discover it by trial and error. Eventually this is the secondary role of a bad diagram in a datasheet, to put you to test the thing and figure it out by yourself. Its not the first time and not the last time I get it like this.
I have some real problem here with the arduino, not being able to get lower than 1milisecond down to micro-seconds... and this is leaving me with a very 'flashy' display. I just built the letter-character 'A' and is working but too damn slow "refresh rate". Damn, im upset.

mister @marconi !
here is what you like, a very fast video, of 5minutes !
where I made the first letter-character 'A' but at a very slow refresh rate.

There are no flies on you!

See:

Definition of NO FLIES ON - https://www.merriam-webster.com/dictionary/no%20flies%20on#:~:text=Definition%20of%20no%20flies%20on,are%20no%20flies%20on%20him.

PS: As one colleague to another - please watch your language otherwise the Forum will ban you and that would be a shame.