Bit's Byt's Hz Calculation Question

Hy,
My question is eigendlich simple but I'm unsure of the result.

Data sheet page 3: http://www.seeedstudio.com/document/pdf/WS2812B%20Datasheet.pdf

There are 400KBit / s indicated, right?

We are looking for the maximum number of LEDs at 5KHz writing speed.

Background:
I want to write a 3D image with a rotating display from LED's.
The display rotates at 3000 RPM = 50Hz
It should show 100 levels.
Thus 50Hz * 100 = 5000Hz = 5KHz, right?.

Now I would like to know how many LED's I can with an Arduino maximum control to get out whether these LED's überhaubt suitable.

According to my calculation, there are 80 LEDs. I am afraid but errors in the conversion!

In the worst case per layer all LEDs will be given new values. That is, Which is addressed with the 400 KBit / s 80 participants one after the other, right?

The datarate should be 400 KHz or 800 KHz (FastLed,h library).
Each WS2812B needs 24 bits of data.
Thus at 800 KHz/24 bits/LED, you can send 33,333 LEDs worth of data in one second.
If you want to update at a 50 Hz rate, then you get 1/50 of that, so 666 LEDs.
100 Levels = 6 LEDs per level. If 400K, then just 3.
“The display rotates at 3000 RPM = 50Hz” 3000 rev/minute * 1 minute/60 seconds = 50 revs/sec, or 50 Hz. Ok.

There’s another RGB LED that Adafruit is carrying that use SPI-like signal instead, so clock & data, I think you can send data at 8 MHz speed, 10 times faster. 60 LEDs/level could be obtained.

The idea behind a rotating display is persistence of vision tho, why do you need more than 1 LED per level?

I want to write a 3D image with a rotating display from LED's.

So the LEDs are rotating is that correct?

It should show 100 levels.

You have lost me there, levels of what?

Thus 50Hz * 100 = 5000Hz = 5KHz, right?.

No.

The data rate is 800KHz not 400KHz, look at the timing signal definitions in the following pages.

Each LED takes 24 data bits to set its brightness with a 50uS reset gap. So ignore the gap for a moment you can refresh one LED 33,333 times a second. If you want to refresh the LEDs at a 5KHz rate then you can do this for only 6 LEDs.

But there is a bigger problem if the LEDs are spinning. No matter what rate you can or can not get new data into the LEDs they are driven by a low frequency PWM signal. From the Adafruit page Overview | Adafruit DotStar LEDs | Adafruit Learning System The WS2812 has:-

400 Hz refresh/PWM rate not suitable for persistence-of-vision effects.

That means no matter how fast you push the data in it takes 2.5mS for it to flash once giving you a brightness level.

Simply put that LED is not suitable for your project.

Yes the LED's turn.

Hmm how do I explain best what I want to build.

Ok this video demonstrates the composition of a layer:

125 Layers A bit displaced to one another write a 3d picture in the air and each layer has a μC.

I have mistakenly referred to the angle as the layer,

365 ° = 100 steps, not Layer!

I hope so the projects became more understandable.

"You can refresh one LED 33,333 times a second. If you want to refresh the LEDs at a 5KHz rate then you can do this for only 6 LEDs."

I do not understand that? If I can update 1 led with only 33 Hz why dan 6 LED's with 5000Hz? That would have to be less?

The PWM function of the LEDs I have in the context did not overhaubt not mind. Of course you are right that the abselut does not go.

Arduino has no μC with 240 IO pins ... Normal RGB LED's directly at the io's would go synonymous yes but there is not nearly enough io's for. Ideas how to implement this? Finally, it is 10000 RGB
LED's to be controlled.

http://www.ebay.de/itm/3528-SMD-SMT-LED-Red-Green-Blue-Yellow-White-7Colours-Licht-Diodes-Emitting-A3-/332110931039?var=&hash=item4d535aa45f:m:mUSoLdLXR9_2ZQQcK3aHGIw

Layout with 3 atmega2560 Arduino per layer during 3 x 68 io's + 2 pins RS232. At 147 layers, this is 9996 LEDs.

If 4 \$ / μC * 147 Layer * 3 = 1764 \$
That must go cheaper! but how?
Somebody's idea???

LED 33,333 times a second.

This is not 33.333 times a second. In English the coma separates thousands the decimal point is a full stop.

did not overhaubt not mind. O

What?

The rest of the post was nearly as incomprehensible. Please use the link icon for links then they can be simply clocked. Copy and paste over several lines is very tricky on a tablet.

Finally, it is 10000 RGB
LED's to be controlled.

So that is 30000 LEDs what sort of budget do you have. I think you need to be more realistic with your plans.

This is not 33.333 times a second. In English the coma separates thousands the decimal point is a full stop.

Oh OK. Yes I am Germen people. , is . and . is ,
Yet is clearly, sorry!

did not overhaubt not mind. O

There has been a typo in the translator. it should be called:
About the PWM function I have still not minded, that can not work so.

Here again the links to click:

Ok this video demonstrates the composition of a layer:

Yes I have seen it, I am still not clear what a layer is. Is it an individual LED?

Here is a link to a video of my hand driven version Magic Wand on the Raspberry Pi on Vimeo and the hardware write up is here Magic Wand

So if you want 100 RGB LEDs you need 300 outputs. There is no processor that will give you 300 outputs and even if there were you would not be able to drive an LED off each one. The best you can do is to use a port expander like the MCP23S17 or MCP23017. Each one gives you 16 outputs so you will need to attach 19 to what ever processor you use.

This is going to be an expensive project what every way you look at it.