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4981  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: March 03, 2009, 07:16:10 pm
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I for instance have led modules with the codes: SBM-1388ASRG (old) and HLG1388ASR (new).
The new modules are much brighter indeed.
Interesting.  Mine say "TOM-1088DEG"

This is a common "problem" with electronic components and items aimed at large manufacturers of consumer products.  If you want to build, say, a Core-class internet router (required to have a product support lifetime of 10 years by assorted potential customers) using an Intel CPU, you have to deal with a special subset of Intel to get chipsets that are committed to being produced for that sort of timeframe (and while using a cheap off-the-shelf PC motherboard in a commercial product SOUNDS like a fine idea, the average lifetime of a motherboard is appallingly short.  You replace the engineering you might have required to design your own hardware with procurement and testing issues as you try to find "this years compatible replacement" for your original choice...)  Sigh.
4982  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: March 02, 2009, 02:34:11 am
Interesting.  If you light only a couple vertical bars, do you still see the brightness difference?  (I did notice that with more than about 15 columns in a row lit, brightness starts to go down noticeably.  And the Holtek datasheet mentions that the chips may not be up to sinking a full 24 columns worth of LEDs in each row in the mode that this board uses it in.)
I've also noticed in the board I have that the LEDs appear to be "over-driven" - if you start using the built-in PWM the displays don't actually start dimming till you get to about "halfway."

Are you still having the "pulsing" problem?
4983  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: February 25, 2009, 10:06:40 pm
BTW, in case it hasn't been obvious, I've been very pleased with the way this whole "shared development" thing has worked out.

It's good to write software that other people can use.  And it's nice to have received a free toy (Thanks!)  But the best part has been watching people take off with the core functionality and do new things with it.  This is the way Open Source was meant to be (IMO) (and although all too often it consist of people only using what the original authors provided.)
4984  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: February 22, 2009, 03:28:14 am
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The overall intensity of the LEDs is pulsating
As shows up in your video?
No, mine doesn't do that.  Does it do it with the demo code as well?
4985  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: February 12, 2009, 11:37:55 am
huh.  I reversed polarity on the display once as well, and mine still works; I guess I was lucky.

The same company does sell just the LED modules (explicitly bi-color) for less than they cost pre-attached to the board:  http://www.sureelectronics.net/goods.php?id=230

the driver chip on the DP016 board doesn't have enough outputs to do bipolar, of course...
4986  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: February 04, 2009, 11:02:15 am
Still struggling along with the "for publication" article on the code and hardware...
4987  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 27, 2008, 12:28:46 am
I was thinking about that.  Essentially caching the port and bitmask in the data structure (a C++ object would do this fine, but ... I currently don't have a data structure!)  You could do the abstraction at the time the display object is created, and thereafter use more direct access for speed.
4988  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 26, 2008, 10:14:33 pm
Heh.  It's not a HORRIBLE ide; it's just a SIMPLE ide.  I keep typing emacs commands that don't do anything :-(

Experiments with max pin toggle rate (http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1230286016) suggest that the low-level code could be significantly faster if the use of "digitalWrite()" were bypassed by direct port access.  I'm not too inclined to do this; I think it's "fast enough", and I think the whole "pin number" abstraction is very useful.  But if you're really after maximum speed...
4989  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 20, 2008, 12:07:36 am
You CHECKED IN code that didn't even compile!?  For SHAME!    (public verbal flogging is what we do at work for such crimes.  Consider yourself flogged! :-)
4990  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 19, 2008, 11:50:13 am
The PWM is for all the LEDs simultaneously.   So it might be OK for adjusting your whole display for brighter/dimmer room illumination, or minimizing power consumption, but you can't control the different LEDs brightness individually.
4991  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 19, 2008, 03:08:13 am
Something like that.  If you wanted to have all four displays occupy a single coordinate system ((0,0)...(15, 96)), you'd have to also have something in the object initialization that set which display occupied which coordinates, and/or plot() would get a bit more complicated...
4992  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 16, 2008, 08:29:19 pm
BTW, if someone wants something to do to this code, I'd like to see it properly C++ified, such that a particular display becomes a proper "object" with at least associated CS signal and shadow storage (and perhaps the other data lines as well.)   I'm mostly a C programmer (duh) and didn't feel up to making this my first from-scratch C++ effort.

Other things to do:

Text display that accepts strings, and scrolls.
More complete font (and/or smaller font.)
Sprites (tie into existing sprite library?)
Animation primitives.
Download complete bitmap from flash.
Offline bitmap generator for above.


4993  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 16, 2008, 07:55:13 pm
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Could you please tell us what is the licence of the code you have posted here?
Yes; that's one of things I "fixed" in the downloadable versions.
Just so it gets recorded here as well:
The demo16x24 code posted here is all done under the terms of the Berkeley BSD license, which means approximately "use it however you want; no viral effects; no requirement to send back changes; no requirement to release your source; but leave my name and copyright in the source."  Consult you company's legal team for more exact interpretations :-(
(guess who recently completed "mandatory open source SW training" at work ?)

4994  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 16, 2008, 03:05:36 am
The complete code is getting a bit big to post here, but you should be able to get it from http://www.geocities.com/westfw/demo16x24.zip
This version has some 5x7 text capability, with a font for A-Z and 0-9 (the chip does NOT have any internal character generator.)

I'm trying to add some text and explanations to get the whole thing into a more "article-like" publication.  Assuming I get it finished, I'll put a note here and eventually try getting it up on the playgroup as well.  (it is, however, somewhat painful to have working code and sketches and be faced with writing mere text.  Sigh.)

The multiple-write thing is a speedup.  Normally you send a "write data" command, followed by 7 bits of address, followed by 4 bits of data, and then you start a new command.  Most of the library code I wrote does that, so the display is always updated 4bits at a time, taking a good 16-odd "pin wiggles" for each pixel you change.  In the demo program, it seems like that is "fast enough" for most of the things I tried, so I didn't do a lot of additional work.  However, if you send an additional 4 bits of data after the first set, the ht1632 will increment the address and put those in the next word, and so on, for as many words of data as you provide.  That means that you COULD update the entire display in about 12 + (96*4) ~= 400 wiggles instead of 384*16 ~= 6000 wiggles; a rather impressive improvement...

4995  Forum 2005-2010 (read only) / Interfacing / Re: Arduino to 384 LED display module (MCU Interface) on: December 06, 2008, 11:51:17 pm
BTW, my version of life ran significantly faster if I only updated the pixels that changed...  Though I'm not sure that running life faster is necessarily better (and I left the demo code in "slow" update-every-pixel mode, since I claimed that I was demonstrating the performance of doing that...)

For animation in general, you might want to investigate the "multiple write" capability of the chip (as seen in the latest code dump in ht1632_clear())
Code:
/*
 * ht1632_clear
 * clear the display, and the shadow memory, and the snapshot
 * memory.  This uses the "write multiple words" capability of
 * the chipset by writing all 96 words of memory without raising
 * the chipselect signal.
 */
void ht1632_clear()
{
  char i;

  ht1632_chipselect(ht1632_cs);  // Select chip
  ht1632_writebits(HT1632_ID_WR, 1<<2);  // send ID: WRITE to RAM
  ht1632_writebits(0, 1<<6); // Send address
  for (i = 0; i < 96/2; i++) // Clear entire display
    ht1632_writebits(0, 1<<7); // send 8 bits of data
  ht1632_chipfree(ht1632_cs); // done
  for (i=0; i < 96; i++)
    ht1632_shadowram[i] = 0;
}

(my; this worked out pretty nicely.  I got a display and a pleasant diversion, and the code works and seems to be usable, and assorted others have taken off and done additional neat things with it!)
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