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My Latest Project - A POV LED Display!

 
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retrobrad
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PostPosted: Sat Feb 16, 2008 10:40 pm    Post subject: My Latest Project - A POV LED Display! Reply with quote

Hi Guys!, heres my latest project i have been working on for the past week.

It uses 8 RGB (red green blue) leds, a pic microcontroller, an eprom and a few tri-state buffers / latches.

basically, the leds are continually changing / flashing and when you spin these leds it actually creates images in the air! its all to do with persitance of vision and the fact that the human brain can't interpret the info fast enough, so instead of seeing pretty flashing lights - it looks like a complete image!

heres a photo:




and heres a link to a video of it on youtube...

http://au.youtube.com/watch?v=gklBWwGyreM


Last edited by retrobrad on Sun Feb 17, 2008 9:18 am; edited 2 times in total
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tomz/TIDE
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PostPosted: Sat Feb 16, 2008 11:08 pm    Post subject: My latest project - A POV LED Display Reply with quote

NICE..............Imagine all the advertising applications you could use this in if developed (and marketed further) the virtual world is fast upon us.

Okay so where are the schematics for it? Wink

BTW-How many hours did it steal from your life

Smile tomz Smile
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retrobrad
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PostPosted: Sun Feb 17, 2008 8:38 am    Post subject: Re: My latest project - A POV LED Display Reply with quote

tomz/TIDE wrote:
NICE..............Imagine all the advertising applications you could use this in if developed (and marketed further) the virtual world is fast upon us.

Okay so where are the schematics for it? Wink

BTW-How many hours did it steal from your life

Smile tomz Smile


Hi tomz, i dont have a schematic drawn up but heres a block diagram of it.



HERE'S HOW IT WORKS:

the pic microcontroller basically tells everything what to do (it's the brains of the unit) The 27c512 eprom holds all the data to be displayed on the leds. the two 74373 latches / buffers on the right of the picture are used to address the 27c512 (16-bit address bus) then finally the three 74373's to the left of the picture grab all the colour data from the eprom and then will display this data on the leds at the right time.

Okay that was a nice introduction Smile

The microcontroller will place 00000000 binary on its' 8-bit output port, PORTB it then enables the first 74373 connected to the eprom address bus and this will hold the first 8-bits of the address bus at 00000000 binary. It then does the same for the second 74373 which then means that the eprom is starting at the very first address - 00000000 00000000 binary.
(remember it has a 16-bit address bus...)

it also sends a signal to the three other 74373's (connected to the leds) to make sure the leds are turned off) i.e it disables the output to the leds.

Now thats the basic setup procedure...

Okay, every address of the eprom holds 8-bits of data (or 1 byte) the microcontroller will send 8-bits to the red latch (red memory if you like) then increment to the next address which will be 0000000 00000001 and it will send this data to the green latch, then it will goto the next address 00000000 00000010 and send it to the blue latch. so this is three bytes of information and the registers are now containing their relevant info. Now the microcontroller will enable the output to the leds and all the data will show on the leds.

It will display this info for just a fraction of a second and then turn them off again - it will then repeat this cycle over and over again i.e count to the next memory location send then data to red, count to the next location, send the data to green, then count to the next location and send it to blue - it will then enable the led output and it will display the next line of data.

it's a very simple process but achieves some pretty cool results!

If anyone wants more info - just let me know, im always happy to help out.

and if anyone wants the PCB schematic i can send them to you.
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tomz/TIDE
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PostPosted: Fri Mar 07, 2008 8:54 pm    Post subject: My latest project - A POV LED Display Reply with quote

Thats very interesting,although I understand the foundation of the code,the 16 bits is an intersting thing to play with being used to 8,never mind it works and a s VERTIO pointed out it could be improved with some improvisation (I 1st learnt this word on C64 Smile )

VERTIGO-Sorry mate,I deleted your last post here because I found it highly inflamitory (not towards me) anyway Im sure you could have phrased your words slightly differently and still managed to say what you did say in that post.

I still cant help wondering about the potential of this technology if it was fully applied to advertising.. Smile

Smile tomz Smile
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VERTIGO
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PostPosted: Sat Mar 08, 2008 9:23 am    Post subject: Reply with quote

Thats all right. I think that the idea is cool, but the project needs a sensor to tell the AVR what the starting points are. I used hall effect switches on a similar program. However I also used PWM to control the motor speed and the hall effect switch to control the display, this has the effect of making the program more stable and allows you to work on really cool graphics later on. I changed the hall effect switch with a more sensitive sensor which are avaliable from Farell. I also made an IR serail comport for my laptop which lets me control the messages scolling speed, font, size, colour, and brightness.
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VERTIGO
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PostPosted: Sat Mar 08, 2008 10:24 pm    Post subject: Reply with quote

tomz/TIDE, you seem to know a great deal. MP me if you have some topics that you feel should be explained. Programming is - outter edges for this forum. I feel the knowlegde base is ok. However the know-how is bad! and thus, this is poorly explained by members in the forum arena.

regards,

VERTIGO -
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retrobrad
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PostPosted: Sun Mar 09, 2008 7:12 am    Post subject: Reply with quote

VERTIGO wrote:
tomz/TIDE, you seem to know a great deal. MP me if you have some topics that you feel should be explained. Programming is - outter edges for this forum. I feel the knowlegde base is ok. However the know-how is bad! and thus, this is poorly explained by members in the forum arena.

regards,

VERTIGO -



Okee Dokee people, Vertigo's posts were a good laugh for a while but now i feel it's time for him to go - i have just banned his username and now maybe we can go back to a friendly forum Smile


I think the funniest thing is that he keeps complaining about everything im (supposedly) doing wrong - yet all my projects seem to work just fine, hmm...
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