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+--- Thread: DIY Ambient Lighting (/showthread.php?tid=110852)
- N3MIS15 - 2011-11-22
UNO works but is limited to two outputs, mega has 4. Just got my setup running with my mega last night.
4 outputs is nice but I was wondering if I could get more using shift registers or something similar. Any ideas?
- TSS23 - 2011-11-22
What means is limited to two outputs?
Which impact has this on the configuration or setup of the ambilight?
Sorry I'm a Arduino noob :-)
- N3MIS15 - 2011-11-22
Boblight uses the PWM outputs on the arduino. UNO has 6, mega has 14 I think. Each output is designated a color (red, green and blue). A single rgb led or strip requires 3 of these outputs (1 for each color), therefor the UNO needs 6 PWM outputs to control 2 LEDs or strips and mega needs 12 PWMs to control 4.
- TSS23 - 2011-11-22
Sorry, one further question.
How many (WS2801 or whatever driven) LEDs can I connect via one stripe?
So let's say if I can connect e.g. 100 LEDs to an UNO and control them, why should I go and get a MEGA?
Sorry I'm dumb. :-(
- ubuntuf4n - 2011-11-22
It's all about the channels.
The max amount of channels is limited, so more channels mean a more realistic effect.
Beside that, yes you can use as many LEDs as you want.
As long as you drive them with enough power.
- TSS23 - 2011-11-22
Now I feel more confused than before I started to ask questions.
Sooo....
I thought that I can add one of those 25 LED WS2801 strands to a Arduino UNO (or whatever) and have a 25 channel ambilight. If I need more than one strand I need an other arduino?
Am I wrong?
- N3MIS15 - 2011-11-23
Post removed.
I think the confusion is all my fault :/
I just realised you were looking to get the 'strands' and not 'strips' like i have used. seems you are doing the adalight method, maybe someone with an adalight setup can help u. sorry for the mess up
Or try http://ladyada.net/make/adalight/
- Cribbe6 - 2011-11-23
The adalight uses serial output and only use 3 wires to control the LEDs.
So you can use as many LEDs as you want and the only thing limiting you is the power you can provide to the LEDs from a external adapter.
So yes there is no need for a MEGA if you are planning to use the WS2801 strands.
I use a UNO and 2 x 25 LEDs
- MartijnGP - 2011-11-23
Damn, this WS2901 implementation is really nice! I've been looking at 6 to 8 small strips of LED behind my TV but as it's 50 inch having just 2 sections of color on either side is going to look really weird. Having more would mean I would need to many PWM outputs. I could do this with TLC5940 IC's but they are rather complicated to drive and would involve a crapload of wiring, transistors, resistors and other stuff that I don't want.
This looks slightly more expensive as I would need 2 strips to have a nice coverage, but in the end it might even be cheaper because of (the lack of) failing experiments and broken components. Also, with the straints running on 5V common cathode, the risk of frying the Arduino is much lower compared to a 12V supply which could jump on the Arduino and bake the chip.
I wonder though if an ATMega 328 can run all of those (50 in my case) LEDs. They are 24 bits, times 50 is 1200 bits which you would need to shift out every time. You'd need at least 24 Hz to run nicely with HD (1080p24) material which means 1200 * 24 = 28.800 bps serial output. I don't know if this is at all possible. After all, you need to push and latch all those bits with a timer on each change.
- Cribbe6 - 2011-11-23
My UNO board use ATMega and can run 50 LEDs with no problem. You need to consider that for a slightly bigger cost you get 48 more sections of different light. I really makes a huge difference having the light change not only on one side of your TV, but on different parts of that side.
- MartijnGP - 2011-11-23
Cribbe6 Wrote:My UNO board use ATMega and can run 50 LEDs with no problem. You need to consider that for a slightly bigger cost you get 48 more sections of different light. I really makes a huge difference having the light change not only on one side of your TV, but on different parts of that side.
I don't get the bigger cost part? How would you get 48 more?
I ment I was planning on having a regular (R, G, B, GND) cuttable LED strip which I would then cut in 8 pieces. 2 on each side of the TV. I would also need 2 of those digital strips if I were to have them on the edge of my TV as the circumfence of my TV is nearly 4 meters and I calculated the strings to be about 2 meters in length.
How long do you need to wait before shifting out each color? I'd think it would take a while to reach the last chip in the string. with such a daisy-chain configuration.
- TSS23 - 2011-11-23
Thanks Cribbe6 for clearing this issue.
@MartijnGP
Look at Cribbe6's and the link I posted above and you will see that you can get a 50+ channel Ambilight driven by an Arduino UNO.
edited:
Sorry I'm too slow. See Cribbe6 post
- Cribbe6 - 2011-11-23
Sorry missed some things in your post.
They shift virtually at the same time.
You will never see a difference between the first and the last LED providing they show the same color that is
I would not worry to much. Get a UNO board and 2 x 25 LED from adafruit.com.
I can really recommend this setup.
- pike - 2011-11-23
I only see one drawback with these "ledpixels", and that is that they are 8bit only. You get 12bit with TLC5940.
- MartijnGP - 2011-11-23
Cribbe6 Wrote:Sorry missed some things in your post.
They shift virtually at the same time.
You will never see a difference between the first and the last LED providing they show the same color that is
I would not worry to much. Get a UNO board and 2 x 25 LED from adafruit.com.
I can really recommend this setup.
Having all those LEDs in the same color kind of defeats the purpose of having multiple controllers, don't you think? I could just buy a 5M LED string and hook it up to my Arduino with just 3 transistors and a resistor.
@pike: 8 bit per color. Makes 24 bit full color, which is decent.