This kind of information is just what I'm needing to get together.
I'm still fumbling around with my Propeller Mobo design. I'm hoping I'll have some pictures
of the 1st revision prototype in a week or so to share with everyone.
I'm going to do this project if it kills me ! I want to do one of the large billboard signs.
There like 40ftx20ft or so. But my boss thinks we should just do one like 8ft. by 3ft. to start
with.
I really think the Propeller will do the job. But the final circuit design will also be a factor in determining that.
Just for giggles I've attached the Excel Workbook with my basic 8-channel PWM (this doesn't include the frequency divider on this version...).
The idea is that you would build a VHDL version of this in a CPLD and parallel-word (16-bit) load the data into the registers as needed.· By injecting a clock (or building a simple self-oscillating circuit around the CPLD), the logic runs the duty cycle PWM based on the input frequency - completely separate from the data input logic (basically you can input data at your pace, and it will run the pixel by itself).
Just an idea.· I had contructed this earlier with 32-adresses (when I received my Propeller chips) to test out a near-real-time Heads-Up-Display concept based on a Propeller (bounce light from RGB LEDs off the inside of a windshield).
Doing video, it's actually very effective to draw one line at a time.· With 320x240, you could do (10) 32-channel CPLDs and load each pixel left to right.· When starting to draw the next line, you'll want to have the previous line persist until the pixel on the line below needs to be loaded (in a pattern like done below - O = On, . = Off):
This would require a little additional logic to do (shifting the output pin row on a per-pixel basis), but will help with the brightness of display in the end (persistence of vision - longer persistence = more perceived brightness), and will reduce the over-all power draw (one line of 320 RGB LEDs·driven at [url=mailto:20mA@2.5vDC]20mA@2.5vDC[/url] = 48 Watts).
Cheers!
-Tim
P.S. Having a task specific ASIC based on this concept has been kind of a desire of mine - and I think large format LED sign manafacturers would be doing this already. -T
Post Edited (GreyBox Tim) : 12/4/2006 2:35:03 AM GMT
Description:·
A 16x16 LED RGB Matrix Billboard Panel with controller that is scalable.
¼ “ Black Acrylic Panel 12” square
Standard PCB matrix design sits on top of the panel. ·
Here’s an example of the PCB schematic being used. http://www.ledtronics.com/ds/RGB1004/g1004001.pdf
NOTE: I’m only using the PCB schematic at the very bottom expanded to 16x16
not the actual led panel (That I'm building from sctarch). ·
Each panel has 256 groupings of three RGB led’s 19mm pitch
for a total of 768 LED’s per panel. ·
Propeller ProtoBoard will be the controller
***
I just wanted to give an update on this project; it’s been some time in design. ·
I’ve been very busy designing the front panel, general overall architecture
Sourcing materials, LED’s and building my toolbox with much needed prototyping parts. ·
So far I’ve got most all of the precision measurements down and I’m hoping to have the Matrix PCB completed in about two weeks. ·
The front panel is going to be Black acrylic ¼ inch thick; it’s going to have 768 holes
In groupings of RG and B (19mm pitch). I’m going to use a standard 3 LED grouping matrix design for the PCB terminated into headers which will sit flat onto the panel. ·
I’m thinking of using the ProtoBoard with 4 standoffs in the center of the matrix PCB with TLC5940’s and ribbon cables going to the panel headers. I will then need to design a general connector onto the ProtoBoard that will support 10+ panel groupings. ·
BTX has started some work on a spin object to drive the TLC5940’s here’s the link http://forums.parallax.com/forums/default.aspx?f=25&m=164062 ·
I’m going to have pictures as soon as I actually get something completed! ·
This is a big project for one person. ·
Here’s my project plan (without schedule) ·
1. Matrix panel design & fabrication / tooling·· - DESIGNS COMPLETED
2. Matrix PCB fabrication / panel hookup / water proofing design / tooling – IN 2· ··· WEEKS! ·
3. Matrix Module integration / chassis / electronics MCU matrix prototype design ··· (When will the ProtoBoards be here?) ·
4. Sign integration / chassis / electronics / power supply / tooling
5. Communications prototype / RF / Cellular
6. External Chassis / tooling
7. BOM / EBOM / Parts Sourcing
8. Zoning / Regulations / Fed & State laws
9. Installation / maintains & tooling
10. Sales & Marketing – Web site design - (Could Parallax help with this ?) Just a thought ?
11. Manufacturing process & life cycle ·
Well, I send some pictures in about a month or so. ·
I’m going to do this project if it kills me! Ha, Ha… you all don’t forget to bring flowers Ha.. Ha..! ·
I’ll soon be turning much attention back to the Propeller chip and to 5v FRAM memory
designs. ·
Thanks for all the support!
-Areal Person · ·
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
Well, don't let it kill you! I think the prop would be pretty excellent for this project. Be sure to search the web carefully for "prior art". For example: www.google.com/search?hl=en&q=sparkfun+rgb+matrix&btnG=Google+Search
I made a red one in the old days before blue LEDs were invented, and I'm not dead yet. A one-MIPs 8-bit processor with 32K bytes of RAM could keep up with 280 LEDs with two bits of control per LED back then, so I would guess that the propellor could do the job for you now with 768 x 3 LEDs. A lot depends on how many bits per LED you will use to control brightness. Keep us posted!
Please do not underestimate the inefficiency of a simple resistor to limit the LED current, most of the energy would be lost in the resistor if you choose this solution.
You could try to lower the power supply voltage, so that you could use a lower value resistor. But the problem with that is that any drop in the power supply voltage would immediately have a big influence on the brightness of the LED's. When you need hundreds of Amperes to feed the LED's you need -very- thick wiring to keep the power drop within an acceptable range.
Another problem is that brightness variations in the LED's would interfere with the color tint. If your display would be driven all white, from a distance it would look "spotty", with areas where the display would not be evenly white but tinted red, green or blue.
You need a mechanism to correct the brightness variations of the LED's so each triplet of Red, Green and Blue LED's would generate the same tint of white when turned "all on".
I would suggest using something like the National LM3501 Led driver converter to optimize power consumption, and correct brightness variations.
Ok,
Here's what I've managed to get done on this so far. I first had to build a CNC machine
so I could mill the double sided PCB and drill the holes in the black acrylic panel.
This lab panel is just 9x15, it's 19mm Dot Pitch and uses three Led's per pixel, they are RG & B.
I'm going to be building 1ft. panels (soon), that are connectable, so I can make any size sign.
The plan is to use the Propeller Protoboard as the center controller for each 1ft. panel
I think I need to code a Pixel object in spin that works with the three basic pixels in a group
and also I need to add a duty cycle so I can do color mixing.
I'm going to be adding some Led drivers like the TLC5940, maybe Fram Memory etc. etc.
I'm almost ready to do some 1ft. panels that will snap together, I'm talking to a PCB manufacturer in Japan.
I really need some help after working with that DIY CNC machine !
I've still got to do allot of electronix work and spin/asm programming.
I'm hoping to have a completed product ready for JIT & BTO in about 3 months.
WOW, nice work on all that. I noticed the LEDs have a fairly narrow viewing angle, is that going to cause problems? For indicator LEDs on my projects I often use sand paper scratch up the LED's lens for a wider viewing angle.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Lunch cures all problems! have you had lunch?
I had not thought much about the viewing angle, most of the specs I looked
at used that led (5mm 20~25 deg). It may be, I think I will know more when I do one of the larger panels.
The cheap movie was done on my cheap camera, and it looks like some of the led are not showing up.
But you can really see them. Viewing angle might be a problem if your looking at a 7x8 ft. sign passing
on the road.
Thanks,
-Areal
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
Areal:
You name this thread: LED Video screen/monitor, so in this case, I suggest you, to use 100-130 degrees angle LED's.
And maybe reconsider the LED's position in the boards, for this, look for some LED's screens in the web, to know more about their convenient position in the table.
Same, you was doing a great job !!! keep us posted !!
Your CNC machine looks great too !! congratulations !!
Thanks, Yep, your 100% right, I should have named it.
Gigantic Imposable Billboard Monitor.
The next goal is to do a 2'x2' prototype so I have somthing to work with... (Each 1ft. panel is going to be managed by a Propeller.)
Then a 7'x9' (Thats in feet). That would boost my confidance a little. ( I already have many, many parts, and I'm going to
Hong Kong in about two weeks)
Then I would like to do one that kinda looks a little like this one....
But... I think I've got just a little more catching up to do...
But... I'm not gonna quit. quitters never win.
Besides, it's allot of fun, everyone should have dreams and a BIG goal
We know the Propeller, has already & will again, stand the test of time. I just hope my project can too
-Areal
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
Have you thought about trying to make a mechanically scanned version, IE a vertical 'stick' of only 240?? RGB leds, and spin the assembly fast, on the end of an arm, in the horizontal plane...
There is / (or maybe used to be???) a really big >> 1Metre high, 2.5Metre diameter full colour mechanically scanned 'billboard' at terminal B Amsterdam Schipol!!
It will save you a fortune in electronics component costs...
Most of the major LED manufacturers (IE Kingbright etc) manufacture 8 x 8 and 16 x 16 full colour led arrays.
These arrays can be mechanically interlocked, to form larger displays....
The array modules have a high speed serial data in pin (and a daisychain data out pin...), so basically, you apply power, and send an 8 x 8 or 16 x 16 'bitmap' to the array.
There are 2 main modes... you can have a serial connection to each matrix, allowing fast screen updates...
Or.. If you are not fussy about update rate, daisy chain several modules in groups of 2,4,8 or whatever to save on serial connections...
The only tricky part of the project, if you use the first route, is that you would need LOTS of serial connections...
Here's some pictures of the 1ft. mach up's with the Propeller Protoboard as the controller in the center.
I hope to have the fully completed 1ft. panels with all the Led's in 1-2 months. Then all I'll need is to finnish the controller
circuits with the Propeller.
I've got to code a Pixel object in spin that has a PWM duty cycle so I can regulate each of the three RG&B led's so I can do color blending. Has anyone done anything like this kind of Pixel object ?
Comments
This kind of information is just what I'm needing to get together.
I'm still fumbling around with my Propeller Mobo design. I'm hoping I'll have some pictures
of the 1st revision prototype in a week or so to share with everyone.
I'm going to do this project if it kills me ! I want to do one of the large billboard signs.
There like 40ftx20ft or so. But my boss thinks we should just do one like 8ft. by 3ft. to start
with.
I really think the Propeller will do the job. But the final circuit design will also be a factor in determining that.
Thanks,
-Areal
The idea is that you would build a VHDL version of this in a CPLD and parallel-word (16-bit) load the data into the registers as needed.· By injecting a clock (or building a simple self-oscillating circuit around the CPLD), the logic runs the duty cycle PWM based on the input frequency - completely separate from the data input logic (basically you can input data at your pace, and it will run the pixel by itself).
Just an idea.· I had contructed this earlier with 32-adresses (when I received my Propeller chips) to test out a near-real-time Heads-Up-Display concept based on a Propeller (bounce light from RGB LEDs off the inside of a windshield).
Doing video, it's actually very effective to draw one line at a time.· With 320x240, you could do (10) 32-channel CPLDs and load each pixel left to right.· When starting to draw the next line, you'll want to have the previous line persist until the pixel on the line below needs to be loaded (in a pattern like done below - O = On, . = Off):
. . . . . . . . . .OOOOOOOOOOO
OOOOOOOOO. . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .
This would require a little additional logic to do (shifting the output pin row on a per-pixel basis), but will help with the brightness of display in the end (persistence of vision - longer persistence = more perceived brightness), and will reduce the over-all power draw (one line of 320 RGB LEDs·driven at [url=mailto:20mA@2.5vDC]20mA@2.5vDC[/url] = 48 Watts).
Cheers!
-Tim
P.S. Having a task specific ASIC based on this concept has been kind of a desire of mine - and I think large format LED sign manafacturers would be doing this already. -T
Post Edited (GreyBox Tim) : 12/4/2006 2:35:03 AM GMT
Hello everyone,
I’ve been busy in design here what I'm building
Description:·
A 16x16 LED RGB Matrix Billboard Panel with controller that is scalable.
¼ “ Black Acrylic Panel 12” square
Standard PCB matrix design sits on top of the panel.
·
Here’s an example of the PCB schematic being used.
http://www.ledtronics.com/ds/RGB1004/g1004001.pdf
NOTE: I’m only using the PCB schematic at the very bottom expanded to 16x16
not the actual led panel (That I'm building from sctarch).
·
Each panel has 256 groupings of three RGB led’s 19mm pitch
for a total of 768 LED’s per panel.
·
Propeller ProtoBoard will be the controller
***
I just wanted to give an update on this project; it’s been some time in design.
·
I’ve been very busy designing the front panel, general overall architecture
Sourcing materials, LED’s and building my toolbox with much needed prototyping parts.
·
So far I’ve got most all of the precision measurements down and I’m hoping to have the Matrix PCB completed in about two weeks.
·
The front panel is going to be Black acrylic ¼ inch thick; it’s going to have 768 holes
In groupings of RG and B (19mm pitch). I’m going to use a standard 3 LED grouping matrix design for the PCB terminated into headers which will sit flat onto the panel.
·
I’m thinking of using the ProtoBoard with 4 standoffs in the center of the matrix PCB with TLC5940’s and ribbon cables going to the panel headers. I will then need to design a general connector onto the ProtoBoard that will support 10+ panel groupings.
·
BTX has started some work on a spin object to drive the TLC5940’s here’s the link
http://forums.parallax.com/forums/default.aspx?f=25&m=164062
·
I’m going to have pictures as soon as I actually get something completed!
·
This is a big project for one person.
·
Here’s my project plan (without schedule)
·
1. Matrix panel design & fabrication / tooling·· - DESIGNS COMPLETED
2. Matrix PCB fabrication / panel hookup / water proofing design / tooling – IN 2·
··· WEEKS!
·
3. Matrix Module integration / chassis / electronics MCU matrix prototype design
··· (When will the ProtoBoards be here?)
·
4. Sign integration / chassis / electronics / power supply / tooling
5. Communications prototype / RF / Cellular
6. External Chassis / tooling
7. BOM / EBOM / Parts Sourcing
8. Zoning / Regulations / Fed & State laws
9. Installation / maintains & tooling
10. Sales & Marketing – Web site design - (Could Parallax help with this ?) Just a thought ?
11. Manufacturing process & life cycle
·
Well, I send some pictures in about a month or so.
·
I’m going to do this project if it kills me! Ha, Ha… you all don’t forget to bring flowers Ha.. Ha..!
·
I’ll soon be turning much attention back to the Propeller chip and to 5v FRAM memory
designs.
·
Thanks for all the support!
-Areal Person
·
·
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
what do you expect ? I'm a programmer.
I made a red one in the old days before blue LEDs were invented, and I'm not dead yet. A one-MIPs 8-bit processor with 32K bytes of RAM could keep up with 280 LEDs with two bits of control per LED back then, so I would guess that the propellor could do the job for you now with 768 x 3 LEDs. A lot depends on how many bits per LED you will use to control brightness. Keep us posted!
You could try to lower the power supply voltage, so that you could use a lower value resistor. But the problem with that is that any drop in the power supply voltage would immediately have a big influence on the brightness of the LED's. When you need hundreds of Amperes to feed the LED's you need -very- thick wiring to keep the power drop within an acceptable range.
Another problem is that brightness variations in the LED's would interfere with the color tint. If your display would be driven all white, from a distance it would look "spotty", with areas where the display would not be evenly white but tinted red, green or blue.
You need a mechanism to correct the brightness variations of the LED's so each triplet of Red, Green and Blue LED's would generate the same tint of white when turned "all on".
I would suggest using something like the National LM3501 Led driver converter to optimize power consumption, and correct brightness variations.
Mahjongg.
www.asm.ro/fpga/files/xc_es-tsquare51.pdf
Mahjongg
Sorry, the schematic that you'll use, is conmonn cathode, the TLC5940 uses the common anode·mode wire
What's wrong ?
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Regards.
Alberto.
Here's what I've managed to get done on this so far. I first had to build a CNC machine
so I could mill the double sided PCB and drill the holes in the black acrylic panel.
This lab panel is just 9x15, it's 19mm Dot Pitch and uses three Led's per pixel, they are RG & B.
I'm going to be building 1ft. panels (soon), that are connectable, so I can make any size sign.
The plan is to use the Propeller Protoboard as the center controller for each 1ft. panel
I used Eagle and a script called PCB-GCODE to generate the Gcode commands.
It took allot of work to get it right, her's a picture of the CNC machine.
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0509.jpg
Here's some pictures of the basic panel, I just have wires hooked up to
the Led Matrix directly from the Propeller.
Here's a general picture of the unit...
The space accross the top and side of the face panel is for some control switches and knobs
to do some cool stuff a little latter.
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0504.jpg
A different angle...
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0505.jpg
Front of the panel...
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0506.jpg
The copper PCB connected from the back...
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0508.jpg
An Eagle schematic
http://i192.photobucket.com/albums/z59/deleteallusers/6x6.jpg
A picture of one of the first boards (Columns back side). (It has some isolation problems that were fixed)
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0485.jpg
The front side... remember this was the first board I cut
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0484.jpg
Here's a movie clip showing the led flashing, they start off just flashing
then I light them all up at 60Hz.
http://s192.photobucket.com/albums/z59/deleteallusers/?action=view¤t=DSCF0511.flv
I think I need to code a Pixel object in spin that works with the three basic pixels in a group
and also I need to add a duty cycle so I can do color mixing.
I'm going to be adding some Led drivers like the TLC5940, maybe Fram Memory etc. etc.
I'm almost ready to do some 1ft. panels that will snap together, I'm talking to a PCB manufacturer in Japan.
I really need some help after working with that DIY CNC machine !
I've still got to do allot of electronix work and spin/asm programming.
I'm hoping to have a completed product ready for JIT & BTO in about 3 months.
Here's a little different video of it on YouTube.
http://www.youtube.com/watch?v=Q9TkhWOgwHE
What do you think ?
-Areal Person
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
what do you expect ? I'm a programmer.
Post Edited (Areal Person) : 9/5/2007 9:28:29 PM GMT
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Lunch cures all problems! have you had lunch?
at used that led (5mm 20~25 deg). It may be, I think I will know more when I do one of the larger panels.
The cheap movie was done on my cheap camera, and it looks like some of the led are not showing up.
But you can really see them. Viewing angle might be a problem if your looking at a 7x8 ft. sign passing
on the road.
Thanks,
-Areal
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
what do you expect ? I'm a programmer.
That is very nice what you have so far
···············
····················· I am going to watch this post to see how it come along
········································
··························· Keep up the the good work
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··Thanks for any·
·
·
·
·
Sam
You name this thread: LED Video screen/monitor, so in this case, I suggest you, to use 100-130 degrees angle LED's.
And maybe reconsider the LED's position in the boards, for this, look for some LED's screens in the web, to know more about their convenient position in the table.
Same, you was doing a great job !!! keep us posted !!
Your CNC machine looks great too !! congratulations !!
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Regards.
Alberto.
Thanks, Yep, your 100% right, I should have named it.
Gigantic Imposable Billboard Monitor.
The next goal is to do a 2'x2' prototype so I have somthing to work with... (Each 1ft. panel is going to be managed by a Propeller.)
Then a 7'x9' (Thats in feet). That would boost my confidance a little. ( I already have many, many parts, and I'm going to
Hong Kong in about two weeks)
Then I would like to do one that kinda looks a little like this one....
http://www.thesignpeople.net/images/sotw/Lamar%20Daktronics%20billboard.jpg
(You know they REALLY make good signs.)
But... I think I've got just a little more catching up to do...
But... I'm not gonna quit. quitters never win.
Besides, it's allot of fun, everyone should have dreams and a BIG goal
We know the Propeller, has already & will again, stand the test of time. I just hope my project can too
-Areal
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
what do you expect ? I'm a programmer.
There is / (or maybe used to be???) a really big >> 1Metre high, 2.5Metre diameter full colour mechanically scanned 'billboard' at terminal B Amsterdam Schipol!!
It will save you a fortune in electronics component costs...
Try Gooling things like 'propeller clock'
Regards MRB
These arrays can be mechanically interlocked, to form larger displays....
The array modules have a high speed serial data in pin (and a daisychain data out pin...), so basically, you apply power, and send an 8 x 8 or 16 x 16 'bitmap' to the array.
There are 2 main modes... you can have a serial connection to each matrix, allowing fast screen updates...
Or.. If you are not fussy about update rate, daisy chain several modules in groups of 2,4,8 or whatever to save on serial connections...
The only tricky part of the project, if you use the first route, is that you would need LOTS of serial connections...
Regards MRB
I hope to have the fully completed 1ft. panels with all the Led's in 1-2 months. Then all I'll need is to finnish the controller
circuits with the Propeller.
I've got to code a Pixel object in spin that has a PWM duty cycle so I can regulate each of the three RG&B led's so I can do color blending. Has anyone done anything like this kind of Pixel object ?
Here's the photo's
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0511-1.jpg
http://i192.photobucket.com/albums/z59/deleteallusers/DSCF0510.jpg
Thanks for all the ideas and input ! I may need to use them.
I need all the help I can get.
-Areal
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
I have a tree growing out of my head, but
what do you expect ? I'm a programmer.