Hi for all,
I need info about large full color (rgb) led display, something like display used on futbool or tenis games,
where I can buy this large panel?
Have someone experience on this field,
best regards
21 Jan 2008 15:19 Re: Giant full color led display
great idea manish12
i have experience with leds drive
and i suggest to start to make a one color giant led panet (red for example ) and if any things go ok we will make the second step (rgb) color
22 Jan 2008 15:13 Re: Giant full color led display
dear sir
about monochrome led panel can we simply use the red (r) output from the vga connector.
as i know the horizantal and vertical signals are serial signals
and we need to make its parallel by using a single line serial to parallel integrated circuit
02 Feb 2008 12:40 Re: Giant full color led display
we have a fault in the concept :
The vertical sync signal tells the monitor to start displaying a new
image or framme, and the monitor starts in the upper left corner
with pixel (0,0)
�� The horizontal sync signal tells the monitor to refresh another row
of 640 pixels
�� After 480 rows of pixels are refreshed with 480 horizontal sync
signals, a vertical sync signal resets the monitor to the upper left
corner and the process continues
�� During the time when pixel data is not being displayed and the
beam is returning to the left column to start another horizontal
scan, the RGB signals should all be set to black color (all zero)
�� In a PC graphics card, a dedicated memory location is used to
store the color value of every pixel in the display. This memory is
read out as the beam scanns across the screen to produce the
RGB signals
03 Feb 2008 10:00 Re: Giant full color led display
Lots of chatter and drawings..... here's a real example of complex PWM action on a single 8x8 RGB matrix connected directly to a single PIC18. The code methods used here can produce 256 levels of color intensity per dot. The demo is a PIC18F4525 on an EasyPIC4 board, programmed using Swordfish Basic:
03 Feb 2008 18:06 Re: Giant full color led display
manish12 wrote:
here is the projected RGB LED matrix board ,
all R , G and B LED terminals shorted and driven by same signal.
picture clear you more !
Then what are you talking about if not driving an LED Matrix? Do the math.... 640 x 480 x RGB = 80 x 60 of these blocks would be required. I have 48mm and 60mm RGB blocks, so that would easily become a VERY large display.
Also, your approach is too electrically simplistic. Firstly, your drawings (the ones I can see here in the forum) don't show a matrix configuration. Next, your circuit with the FET's cannot work due to the fact that each color LED has a different Vf. You would try to turn all 3 on at the same time and only one will light.
Actually it's a start. Doing a small 8x8 matrix will give you an idea of the complexity of driving even a simple LED display. An 8x8 RGB matrix is the same as a 8x24 display and it starts getting complex after that.
manish12 your 640x480 RGB display is a pipe dream for any hobbyist, student etc. Can't be built on any sort of budget in a reasonable amount of time. The cost would be huge as would be the power requirements. I doubt you've done the math involved and what are you hoping to control it with? A video card? It's possible but have you considered what ICs you're going to use for the scan converter?
Interesting thread in theory only, but manish12's theories are based on guesswork not from experience.
I had to quote it because you may delete or edit it. manish12 it's very poor form to edit or delete your posts and change them completely so they now appear out of context. It's ok to repair them as long as the main body hasn't changed.
Your original post indicated you were capable of such a design and would post it here, but you've re-edited that post too. We were all very excited about seeing a massive display and in full color too! but alas, you are just learning like so many of us. I've had decades of experience with electronics and I still learn something new every day. That's what makes electronics, especially microcontrollers so much fun.
We're all here in these forums to hopefully learn and build things based around electronics. Sharing is the key, we can all share our knowledge but try to share facts not speculation unless you say it's an theory or guess or whatever.
You haven't done your homework in this regard, have you?
You haven't shown or said anything here that that could be considered correct, even for a single RGB LED termination. You can stop pretending with your scribbles and jibberish.
Bill is right... this project is way beyond your ability and comprehension. You learn by doing something simpler first, like connecting and running a single small matrix. Even on a small level this type of project is beyond the conceptual ability of 99% of the programmers and hardware people who play with microcontrollers.
stop that
all of us don't need to terminate this tread with no results
we can continue without blame pasicr ,cause he start while all of us wait some one to discuss such project .
any way we need to continue what pasicr start
and first we will discuss the concepts and make monochrome 640x480 led panel
i suggest to make first 640x2 line to test the hardware that we will make
i suggest to discuss this concept :
The screen refresh process begins in the top left corner and
paints 1 pixel at a time from left to right. At the end of the first
row, the row increments and the column address is reset to
the first column. Once the entire screen has been painted, the
refresh process begins again
�� The video signal must redraw the entire screen 60 times per
second to provide for motion in the image and to reduce
flicker: this period is called the refresh rate. Refresh rates
higher than 60 Hz are used in PC monitors
�� In 640 by 480-pixel mode, with a 60 Hz refresh rate, this is
approximately 40 ns per pixel. A 25 MHz clock has a period of
40 ns.
The vertical sync signal tells the monitor to start displaying a new
image or framme, and the monitor starts in the upper left corner
with pixel (0,0)
�� The horizontal sync signal tells the monitor to refresh another row
of 640 pixels
�� After 480 rows of pixels are refreshed with 480 horizontal sync
signals, a vertical sync signal resets the monitor to the upper left
corner and the process continues
�� During the time when pixel data is not being displayed and the
beam is returning to the left column to start another horizontal
scan, the RGB signals should all be set to black color (all zero)
�� In a PC graphics card, a dedicated memory location is used to
store the color value of every pixel in the display. This memory is
read out as the beam scanns across the screen to produce the
RGB signals
640x480 is 307200 LEDs
Nobody is going to build that, the power requirements alone are enormous.
You could by a nice 42" PLASMA TV for less than the cost of the LEDs.
Most folks can barely get though an 8x8 display. The whole thread is pointless.
On this point, I am in full agreement. When the discussion of a large LED display digresses into a discussion of Horizontal and Vertical Sync, then these folks better stick to a TV picture tube, and try to better explain the duties of a microcontroller programmer with some IO to play with.
Notably, nobody is discussing even the simplest mono LED display and how to achieve different levels of "gray-scale" per dot. Something very important to any display that proposes to be anything resembling a decent picture.
06 Feb 2008 17:18 Re: Giant full color led display
WHAT IS NEXT ?
PWM IS MORE COMPLEX FOR VIDEO , JUST THINK DIGITAL OUTPUT WE HAVE AND NEED TO CONTROL INTENSITY THEN OK , BUT HERE IS NOT A 1-2-3-4 LEDS , IT IS HUGE .
NOTE: PWM IS AN ALTERNATIVE IF YOU HAVE ONLY DIGITAL OUTPUT PIN .
NO NEED OF PWM , MAP THE RGB VIDEO SIGNAL INTO THE FULL RANGE OF LEDS VOLTAGE .
