Twister - Driving multiply high powered RGB-LEDs

Hi.

So I want to build 6 x 4 Twister Board using individually addressable 3 W RGB-LEDs, and an Arduino Uno.
Any ideas on how to approach this idea, and is it even possible to do with an Arduino Uno?

Boye:
So I want to build 6 x 4 Twister Board using individually addressable 1 W RGB-LEDs,

Which ones are they? Web link?

Boye:
is it even possible to do with an Arduino Uno?

Why would you think it would not be?

Hi, will the board be lit from below? Would a larger number of smaller leds per square give a more even illumination? For example 9 5050 rgb leds per square. How big is each square?

How many colours will be needed? Will 7 (red, green, blue, cyan, magenta, yellow, white) be enough?

Paul

I made a little mistake, i meant 3w. I thought about using those: http://eud.dx.com/product/jrled-jrled-3w-rgb-3w-50lm-3-led-rgb-light-bead-emitter-white-2-3-3v-844335822 or these: http://www.dx.com/p/3w-led-emitter-on-star-multicolored-rgb-4530#.VChyZ_l_uFE

The board will be made out of 20x20 cm tiles of some sort of diffused hard plastic material, and it will be lit from below like a dance floor.

7 colors will be sufficient.

Ok, I have a suggestion that would make a really simple circuit to drive your leds. However, I have a couple of doubts, so get advice on my suggestion.

Use 9 TPIC6A595 shift registers. Daisy-chain all 9 of the chips together and drive them with the Arduino's SPI outputs. Each chip has 8 high current sink outputs. You will need current limiting resistors between them and the leds.

So here are my doubts about this suggestion:

  1. Those leds draw 350mA per colour. This is right at the limit of what the chips can handle. It is not generally considered wise to run any component at its maximum continuously. However, they are rated for higher currents for short pulses, 350mA is the max continuous current. Also you probably won't have all 8 chip outputs on at the same time.

  2. Running 9 of them in a chain may mean having to buffer the SPI clock and latch signals, so another chip with some logic signal buffers may be needed. But hopefully not.

  3. This will only work with common anode leds. Your first linked item appears to be common anode, but your second link look like common cathode.

Paul

If the images following these links are any indication of the product quality you'll actually receive I would not bother ordering this junk from deal extreme. The soldering looks absolutely terrible!

I already own a pair of http://www.dx.com/p/3w-led-emitter-on-star-multicolored-rgb-4530#.VChyZ_l_uFE (common anode) and they are surprisingly good quality, and thanks. I will look at the shift registers.

I have never tried to use the Arduino's SPI outputs, do you know any good resources or tutorials, or is Google my good friend in this case?

In order to achieve higher currents than the 350 mA max on the shift registers I might use a transistor acting as a switch?

Boye:
The board will be made out of 20x20 cm tiles of some sort of diffused hard plastic material, and it will be lit from below like a dance floor.

I’d use lots of smaller LEDs.

Just chop up some LED strips and glue them to square panels underneath the floor.

fungus:
I'd use lots of smaller LEDs.

I already suggested that, but Boye seems to want to use single 3W leds for each tile.

Boye:
I have never tried to use the Arduino's SPI outputs, do you know any good resources or tutorials, or is Google my good friend in this case?

There are some tutorials on the Arduino Playground I think (click the "Learning" menu above). But it is very easy really.

Boye:
In order to achieve higher currents than the 350 mA max on the shift registers I might use a transistor acting as a switch?

Yes, but in that case there is no point spending extra cash on the tpic6a595, just use the standard 74hc595 and standard transistors like bc337. However, you are talking about 72 transistors! If you can use the tpic chips, that saves a lot of construction complexity and soldering.

Im not settled on the 3W leds, I just thought it would be cheaper, and easier to build?

Boye:
Im not settled on the 3W leds, I just thought it would be cheaper, and easier to build?

(you mean compared to LED strips?)

Cheaper? Depends on how many LEDs you put under each tile.

Easier? Definitely not. LED strips make everything incredibly easy.

Okay so if I use the led strips, how would you drive/control them?
Would you use the shift registers or a dedicated led strip driver for arduino?

If using standard 12V rgb led strips, easiest option would still be tpic6a595 in my opinion. The 350mA currrent limit will probably not be an issue because at 12V the strip will require far less current than your high-power rbg leds. This is because in 12V rgb led strips, the leds are arranged in groups of 3 connected in series which share the same current.

To match your 3W of power per tile, each tile would need draw around 250mA in total at 12V. That's about 85mA each for the R, G & B channels. So perhaps the cheaper tpic6c595 could be used (max 100mA per output). That current could drive 4 groups of 3 leds.

The other option would be ws2812b led strips. These are considerably more expensive, but no driving circuits would be required at all. If you work out the total cost of the project using ws2812b strips versus 12V rgb led strips, including your time designing and building the driver circuits, there may not be much difference. Plus you get more colours. Note ws2812 leds run at 5V rather than 12V, so more current will be needed from your power supply.

Boye:
Okay so if I use the led strips, how would you drive/control them?
Would you use the shift registers or a dedicated led strip driver for arduino?

The LEDs have built-in driver chips. You just connect all the LEDs in a single string and connect one data wire from the Arduino to the first LED.

And… that’s it.