What is the best signal interface for PC ?

[_q12x_]

I mean.... the best and the easiest to use.
I remember back in the 2000's I used a serial interface, I think it was the printer serial port, 25 pins or similar. I believe I even used a mouse port as well, that versatile those systems were back then.
What I could do with it was ... program in C++ and pascal back then, using some imported dll's specific for communication with this serial port, I think it was port 40 or 25? It had a number is all I remember. And I could link to it any transistor base, back then I was working exclusively with BJT's, to light LED's, drive motors, beep some 8ohm I think they were speakers, drive a VU-meter LED bar I think directly from the port pins, without transistors, and also drive IC's , that was the time I learned about multiplexers and expanding the number of output pins. Also input sensors like LDR and buttons. I Loved that kind of easy and straight forward communication.
Today I dont know c++ or pascal anymore, but I am very good in c# and still use VS2010 because its very cool interface and very user friendly overall.
So I want you, to help me first of all, to find the hardware, the port I suppose or something more than a printer port, something more advanced and having more in/out's. The more the better. I want the best you can find for the moment. Best ideas or best adaptations, why not. As long as it's easy and stable to install and use.
And then, the software drivers and possible problems will appear along the way. I can debug a large majority of problems, I grow up debugging computer problems, so I have a 5'th sense for them. Im more concerned about the hardware part and the integration with my win7 that I still run today and my VisualStudio2010 for my c#. I know I still run old software but they are extremely stable and they don't f me up.
Thank you and I'm really curious what you will find for me.

 

[marconi]

https://www.matrixtsl.com/mmforums/viewtopic.php?t=8425

I did some googling and found this. Does it help?

 

[marconi]

q12x. You asked for a video. The letters A to O represent the 16 states of the 4 bit Gray code. The 4 white leds top right are the 4 bit Gray Code. The two 7 segments are numbered representation for the first 12 states of the Gray Code - last 4 states are not decoded because I ran out of space on my home made ROM on the brown veroboard. The eeprom is on the bottom right board on the far right. Enjoy

 

[marconi]

May I suggest a way ahead? It is a seven step approach.

1. Design a way to repetitively scan the 7 x 5 column by column. I showed this in my first video.

2. Now introduce a way to display one pattern of column data say 1010101 which scrolls from left to write on the 7 x 5.

3. Now form a 7 x 5 data table in software.

4. Now write a sub routine to read the data table column by column . Load the data into a 7 bit register.

5. Now add some code to indicate the column number and write this into a register.

6. In hardware make a circuit as I showed you earlier which takes as its input the data in the column and column number at paras 4 and 5.

7. Now load table with chequerboard pattern of bits and check 7 x 5 displays it correctly.

You now have way of displaying anything you write into data table. And this table can change over time if you wish.

 

[marconi]

Good morning mister @marconi ,
Here is something interesting... Im not sure how much may have been influenced my program testing so far, I will have to make a more extensive research on this particular detail, but in time. For the momment, with the programs I run already, I didnt really observed much of a difference to be honest. But it crossed my mind that this little bugger might be important in some special cases, special programs. Time will tell.
So here it is - full view:
View attachment 100791
The blue lines represent the Ground or 0V. I marked with a square the 0V marking next to the metalic pad from which the wire is going beneath the cardboard to that long track on which, each negative pin for all the LEDs are connected. So what I have there is a pull down connection through each 12k resistor put in series to each LED to ground.
View attachment 100792
This problem I realize it yesterday, when I was programming and was meditating to the fact those pins from the IC are not really floating or inAir. I then realized they are actually pulled to ground through each led. And today, I mounted that little switch only between this rail for all the leds and 0V. I tested a couple of normal programs but no visible difference. Ill have to test some in depth programs that I have 'somewhere' that really needs some floating pins. I really hope it will be a difference this time. If not, then, daaaaeeem.

I do not immediately see the connection between the potential of the outputs and its impact on your time problem.

 

[_q12x_]

I do not immediately see the connection between the potential of the outputs and its impact on your time problem.

First off all, congratulation on the movie and showing the full working project. Very fascinating !!!
I still have to try it your way someday, in the future.
-to your question now: - Well, when a pin of the IC is floating , it is not 0V nor 5V. Right? But by having all those leds and resistors to 0V, I efectively put to 0V every IO pin of the chip. THus, not leaving anything really floating. This is important in code, when I am switching from Outputs to Inputs. By switching to Inputs is the programming way of 'floating' the Output. By inversing it. Its a trick learned when I was programming PIC's MCU's. But... having all these pins to 0V ---anyway--- , it doesnt matter if I was switching to Input or to Output in code, because the state was 0V anyway. So the speed was not affected but the entire logic of the code was affected, which is more important and more drastic. I hope is more clear now what I did there.

 

[marconi]

First off all, congratulation on the movie and showing the full working project. Very fascinating !!!
I still have to try it your way someday, in the future.
-to your question now: - Well, when a pin of the IC is floating , it is not 0V nor 5V. Right? But by having all those leds and resistors to 0V, I efectively put to 0V every IO pin of the chip. THus, not leaving anything really floating. This is important in code, when I am switching from Outputs to Inputs. By switching to Inputs is the programming way of 'floating' the Output. By inversing it. Its a trick learned when I was programming PIC's MCU's. But... having all these pins to 0V ---anyway--- , it doesnt matter if I was switching to Input or to Output in code, because the state was 0V anyway. So the speed was not affected but the entire logic of the code was affected, which is more important and more drastic. I hope is more clear now what I did there.

Thank you. I see what you mean. The same applies to the eeprom I used but in its case it did not do anything with the data at its input/output pins until they were selected as such and there was a 'read' signal pulse. I suppose the same applies to the MCP23017. I have not had the time nor inclination to fully understand how the 23017 operates and is used to offer any immediate advice. I remain sceptical though.

 

[_q12x_]

I have not had the time nor inclination to fully understand how the 23017 operates

Dont worry about that. That is my concern.
Some good news. I went to arduino forums and put this entire project we discussed here in their hands to help me make the speed of the led matrix to be faster from the code perspective ofcourse. And the good news is, that I really made it faster than in the very beginning. Its not as fast as yours, it is still flickering but the fv is visible much higher than before. I have tested 2 libraries for coding this MCP through arduino IDE and this eat me some time to concentrate, evaluate, mostly guess and test hundreds of permutations. But it worked, now is considerably faster, because some special functions I learned to use.
I am asking you to make me a circuit drawing of what you just made there. But make it clear enough for me, not a scribbled wire of lines. Make it look good. Like made for me. Thank you. Because I want to try your way as well.
- Oh, and I just changed all the 1.1k resistors with 300R resistors now. Is not full brightness of the led but is a bit more visible than with 1.1k which in daylight was almost invisible, and only in shadow was starting to show its led light. Speaking from the speed of the last program I made last. The leds are dimming as long as the fv/speed is increasing. Especially much more lower visibility on a single full line or full column..

 

[marconi]

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[marconi]

One of the reasons I like working with you is that you are motivated by and enjoy learning from you own experience and trials. And I think you should by now realise that these days my practical work records ‘work in progress’ accompanied by scraps of paper with electrical art on it. I will not therefore and alas and to your disappointment perhaps be producing blueprints to your exquisite standard to follow. We plough our own furrows. At 61 I simply cannot be bothered with the formality after a lifetime of it.

 

[_q12x_]

At least enumerate all the IC's you used and for what purpose if possible and I will do the circuit myself if I will be able to. At least I will give it a try using Proteus simulator.

 

[marconi]

Make a 555 clock running at 1Hz
Connect this clock to a 4 bit counter such as a 7493. The 7493 is ideal because as you know it has integral reset logic.
Wire the 7493 to its reset pins so that it counts in binary 0000 to 0100 - these are the five states to control the scanning of the columns.
Connect the Q outputs of the 7493 to a 74138 to turn the binary sequence into a one-of-five word sequence ie 00001, 00010, 00100.....

Working of 74138 decoder IC - https://www.tutorialspoint.com/working-of-74138-decoder-ic

Use the five bit word to turn on in turn the column transistors Cn I showed in my earlier electrical art. The five Cn transistors must be able to pass a collector current of 7 x one LED current. Base resistor of say 22kR - but I will check this later.

Connect 7 transistors as in my earlier electrical art to the 7 row/lines of the 7 x 5 display with suitable collector and base resistors. I used 1kR and 22kR respectively - but will check later. These transistors only carry the current of one LED.

Connect seven fly leads to the base resistors of the row/line transistors so that you can set up a column pattern by connecting to 5V or 0V 0000000 to turn all column LEDs on and 1111111 to turn all off. The row line transistors switches are negative logic ie active low.

 

[_q12x_]

Ok, thanks mister @marconi , this should be good enough to make the circuit in my simulator.

 

[_q12x_]

I have a slight bad luck that was giving signs for some time but last night I felt it very easy to bent and this is sign it's the last bent will have. If I try to straighten it back again, like I did it a couple times before, in time, it will break for good. So I am taking measures now to make a new one from the scraps I have. That new pointer is actually a brand new one (from ebay) that I cut it into my lathe to try fitting it into this iron body I have. But... its a failure and I could not fit it as the original was. SO now I have to build from ground a new head, using this already busted copper head, but brand new and unused. Whish me luck because I want to finish it at least in 1 day.

 

[marconi]

Just remembered that you will need to invert the 74138 outputs because they are active low. Its output sequence is of the form 11110, 11101, 11011, 10111, 01111.

 

[_q12x_]

Luckily it took me about ~2h to make a new modality of contact for my new heat Iron tip. A new press fitting head that is full iron instead of copper. Only the tip is copper. I test it already and I have to dial to maximum for it to heat up quickly enough. But it works. Yay.... very happy, is stable and working.
I will soon start building the simulation for your circuit.