Engineering solution, take me

  • Dec 24, 2019

Addressable LEDs allow independent control of color and brightness of each LED in the tape, matrix or daisy-chain. Whoever came up with management protocol, just genius!

In 2010, the Chinese company WorldSemi He has released a small octopus chip WS2811, which turned the world of LED effects. This chip will allow to create the RGB-LED arrays with a very simple and convenient control of each individual LED. The LED is connected to the chip and to connect these cells need only three wires - general, nutrition and management.

Power wires connected to all cells in parallel, and the control wire goes from the output of each chip to the input of the next.

In order to independently control each LED, one would come up with a protocol, where each chip would have its address and he would point in the control digital signal, but then would have to do the address jumper for each chip. WS2811 uses a much more elegant solution.

At the chip has no address, all cells are exactly the same. Thanks to the "Protocol push" you can manage thousands of LED cells.

Everything is very simple. The controller sequentially transmits the control command to the input of the first chip. Commands as much as chips in the array is then passed pause, is a sign of the end of transmission.

The first chip receives the command and if he sees that it goes after another team, simply "pushes" command, passing it the next chip, and so on a chain. Once the teams have ended and there was a pause, each chip realizes that the last came command addressed to it and sets the color and brightness of its LEDs, in accordance with this team.

Simple, elegant and very cool! I admire those who invented it.

Number of LED chips in the chain is limited only by the command rate. In order to control the LEDs could slow controllers with weak processor chip supports two data transfer speeds - 400 and 800 kbit / s. Slow-30 sequences can be transmitted per second speed commands 512 LEDs. In the fast - in 1024. Accordingly, if enough Pack 2 times per second, it is theoretically possible to address up to 15,360 LEDs (however, controllers, supporting more than 2048 LEDs, I have not seen).

In 2013, there was WS2812B - this is no longer the chip, and RGB-LED with a chip control that is fully compatible on commands with the WS2811. It became possible to produce as simple and cheap addressable LED strip.

In addition to the tapes, produced and matrix WS2812B.

And yet there WS2812D video LED housing 8mm.

Millions, perhaps billions, and has LEDs with chips WS281 * work in decorative lighting, screens, tickers, advertising around the world. In many ways, their popularity is due to simple and convenient "push protocol."

© 2019 Alex Nadozhin
The main theme of my blog - Equipment for human life. I write reviews, share experiences, talk about all sorts of interesting things. My second project - I test LED lamps and help figure out which ones are good and which are not.