What is the best signal interface for PC ?

[_q12x_]

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.

 

[marconi]

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.

 

[_q12x_]

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.

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.

 

[_q12x_]

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.

 

[marconi]

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.

 

[_q12x_]

Right.... heh, so, how to speed up this thing, to actually display the letter 'A' ?

 

[marconi]

You like a challenge ..........

 

[_q12x_]

If it works, yes. What you have in mind?

 

[marconi]

I am not familiar with the microprocessor board and its programming you are using. Seems odd to me that you cannot speed up the bit rate from these outputs. Perhaps some more reading of the manual.

In my version I store the character data in an eeprom and then read it out quickly to drive the 7x5 display.

Now the weather has cooled it is comfortable enough in my shed to restart work to finish off the project. I am slower than you though! You can see slow test scanning in the attached video.

 

[_q12x_]

Here, I attach the image I made. See if it is of any help.
You are doing much more harder work than me, you are programming it in hardware. I did it faster because it was in software,and is a big difference.
But yours will be faster and display more better than my results, because the arduino board Im using, has some restrictions I didnt discovered to bypass them, or its just stupidly build like that, with a minimum of 1mHz.
This is a plan for the future, and a serious upgrade. I will have to search and ask around for a solution, to link my entire MCP board to my PC, but NOT using arduino, but something else. I already have some usb to TTL very tiny boards, I think, I have to look and see exactly what I have, but the idea of the upgrade will be that I will put aside the arduino and replace it with something faster in IO department, matching and even better than these MCP's operating fv, which is kind of slow, but fast enough for a lot of stuff. So thats in plan and is a bit more complicated to achieve.
- If anyone else that is reading my progress here, can jump with any idea, please do so. Like @timhoward with Teensy board. More ideas please.
I was unsure and I re-check it with the datasheet of the MCP23017. I got this from it:
High-Speed I2C Interface (MCP23017):

• 100 kHz
• 400 kHz
• 1.7 MHz

I can see diferent values there and they have some specificity I dont know yet. All I know is that this MCP chip, driven from I2C, is doing it at 100kHz.
My math... correct it if you see something wrong, im in the art department:
100 kHz = 100000 cycle/second >> 1cycle is at an interval of 100ms ? Is this right?
Also, this MCP chip has another way of connection:
High-Speed SPI Interface (MCP23S17): - 10 MHz (maximum)
Which I have no idea how I may link it...
The problem is that all the wiring on the boards so far is done for I2C communication ! Not for SPI.
The guy who suggested me these MCP's asked me in the beginning, if speed is a problem, and I said "speed is not a problem" but now... with your project, it starts to be one... damn. But as limited as it is so far, I can reorient to other types of projects. At least I tested some limits so far.