New beta release "DMD2" Library

The Dot Matrix Display (DMD) is a 32x16 array of high-brightness LEDs for visually striking effects. [Product Page]
Brissieboy
Posts: 94
Joined: Fri Sep 20, 2013 7:25 am

Re: New beta release "DMD2" Library

Post by Brissieboy » Fri Nov 06, 2015 2:02 am

vishalgupta1991,
The routine which does the updating of the DMDs takes time to update them. The more DMDs - the longer it takes. In order to drive that many DMDs you will need to re-think your design.
If you slow down the rate at which the update routine is called you will be able to drive more DMDs, BUT!!! the display quality will suffer greatly. It will be totally unacceptable if extended to allow for 24 DMDs.
As for RAM usage, each DMD requires and additional 64 bytes for its buffer.
Not sure if any of the Arduinos are capable of driving that many DMDs.
You will probably have to have a number of slave Unos each just driving about 6 DMDs and a master driving those slaves.

vishalgupta1991
Posts: 9
Joined: Fri Oct 30, 2015 12:02 pm

Re: New beta release "DMD2" Library

Post by vishalgupta1991 » Mon Nov 16, 2015 9:45 am

Brissieboy,
Thanks for your help. :)
Can it be possible to change the fonts of dmd library to any other language other than english, because i want to use the native language (Hindi) for scrolling text.
So if it is possible please tell me asap.
Thanks for your entire support.

Brissieboy
Posts: 94
Joined: Fri Sep 20, 2013 7:25 am

Re: New beta release "DMD2" Library

Post by Brissieboy » Mon Nov 16, 2015 11:36 am

vishalgupta1991,
You can make a font do almost anything you like, but there are limits. You can certainly define your own character set.
Have a look around the Dot Matrix Display area of the forum. There is a lot of information already available there.
Here are a couple to start with that may help you understand how the fonts work:
- the attached file 'MyBigFont.h" here has comments to help you understand the font file construction
- this one uses a font to display a graphic

vishalgupta1991
Posts: 9
Joined: Fri Oct 30, 2015 12:02 pm

Re: New beta release "DMD2" Library

Post by vishalgupta1991 » Mon Nov 16, 2015 12:36 pm

Brissieboy,
Thanks for sharing this. :)
And i want to know 1 more thing, i am using arduino mega and node.js for image displaying on dot matrix display and i'm able to get image on 128x48 matrix.
But i have no idea how to scroll images on dot matrix through node.js .
plzz help...thanks in advance.

Loki
Posts: 18
Joined: Mon Jul 06, 2015 7:12 pm

Re: New beta release "DMD2" Library

Post by Loki » Wed Nov 18, 2015 2:01 pm

I use this ugly code:

Code: Select all

void ScrollX(){
int len=0;
if (MESSAGE.length()*8>254)
      { 
        len=254; 
      }
  else if (MESSAGE.length()*8<96)   
         {
        len=96;
      } else if ((MESSAGE.length()*8+MESSAGE.length())>254){len=254;}
      else len=MESSAGE.length()*8+MESSAGE.length();
DMDFrame little=scroll.subFrame(0,0,len,16);
little.marqueeScrollX(-2);
scroll.copyFrame(little,0,0);
bool state;
 for(int x = 0; x < 96; x++) {
    for(int y = 0; y < little.height; y++) {
     if (little.getPixel(x,y)) {state = true;}else{state=false;}
     dmd.setPixel(x+128,y,state ? GRAPHICS_ON : GRAPHICS_OFF);
      }
    }
}
for scrolling on 16x96 (physical 3 DMD length) with max of virtual 16x254

Brissieboy
Posts: 94
Joined: Fri Sep 20, 2013 7:25 am

Re: New beta release "DMD2" Library

Post by Brissieboy » Thu Nov 19, 2015 3:59 am

Sorry vishalgupta1991, but I can't help you much there. I did most of my work before the DMD2 library was released and chose not to migrate as I had done quite a few mods to my version of the earlier DMD library.
Maybe Angus ("angusgr" on here) can help.
I suspect that the library might not be able to handle scrolling beyond 1 DMD high (16 pixels). That was a limit in the original DMD library.

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stryker
Posts: 250
Joined: Sat Jan 14, 2012 2:44 pm

Re: New beta release "DMD2" Library

Post by stryker » Sat Jan 30, 2016 1:07 am

Brissieboy wrote:I suspect that the library might not be able to handle scrolling beyond 1 DMD high (16 pixels). That was a limit in the original DMD library.
I didn't find that limitation - and successfully used my 2 DMD tall font in a marquee in my test sketch. That is using the older DMD library with just the SPI_CLOCK_DIV2 modification in place

Link to video https://www.youtube.com/watch?v=-WhA3xX4dJU
(turn speakers down...I used some royalty free music to replace the loud ambient noise in my phone video)

However like Brissieboy I've not used DMD2 extensively, so can't comment if that limitation is new.
Cheers! Geoff

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stryker
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Re: New beta release "DMD2" Library

Post by stryker » Fri Feb 19, 2016 9:09 am

Hi Angus

I'm finally migrating some older DMD projects to DMD2, and have to agree with others your improvements are solid and impressive. Thankyou.

Just wondering what you have in mind for how the marquee will work since you mentioned there's more functionality expected in that area to come?

Thanks,
Geoff

angusgr
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Re: New beta release "DMD2" Library

Post by angusgr » Tue Feb 23, 2016 5:10 am

stryker wrote: Just wondering what you have in mind for how the marquee will work since you mentioned there's more functionality expected in that area to come?
Mostly that the marquee functionality that's there is currently buggy, but what I plan to provide is the ability to marquee scroll a DMDFrame. It can either be the full display, or you can use dmd.subFrame() to pull out a subsection of the main frame, which you can then scroll independently.

However, I haven't had any time to work on DMD2 for a while (as you've probably noticed), so I'm not sure when I will be able to finish off the marquee support. If you need marquee support at this stage then you're probably better of sticking with the original DMD library, unless you're prepared to do some debugging as well. :|

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stryker
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Re: New beta release "DMD2" Library

Post by stryker » Tue Feb 23, 2016 5:51 am

Thanks Angus,

Based on that feedback I think I'll avoid marquee in this next update. Making the move to DMD2 means leaving the 4k7 pulldown resistor off our board, so this ties in with the next revision of our PCB. The benefits longer term in sticking with the mainstream version of the library rather than having to mod it every time will outweigh the short-term missing marquee.
angusgr wrote:unless you're prepared to do some debugging as well. :|
Always up for some of that! Geoff

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