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La magie de NeoPixel

Incorporating scads of LEDs into an electronic project used to be a hairy prospect, a veritable rat’s nest of wires and code. The arrival of dedicated LED driver chips brought welcome relief, offloading grunt work from the microcontroller and allowing one to focus on the application. Much simpler, but still not “Christmas light” simple.

The WS2812 Integrated Light Source — or NeoPixel in Adafruit parlance — is the latest advance in the quest for a simple, scalable and affordable full-color LED. Red, green and blue LEDs are integrated alongside a driver chip into a tiny surface-mount package controlled through a single wire. They can be used individually, chained into longer strings or assembled into still more interesting form-factors.

Crédit: AdaFruit Industries

Ce qu'il est important de savoir à propos des NeoPixels

  • Not all addressable LEDs are NeoPixels. “NeoPixel” is Adafruit’s brand for individually-addressable RGB color pixels and strips based on the WS2812 and WS2811 LED/drivers, using a single-wire control protocol. Other LED products we carry — WS2801 pixels, LPD8806 and “analog” strips — use different methodologies (and have their own tutorials). When seeking technical support in the forums, a solution can be found more quickly if the correct LED type is mentioned.
  • NeoPixels don’t just light up on their own; they require a microcontroller (such as Arduino) and some programming. We provide some sample code to get you started. To create your own effects and animation, you’ll need some programming practice. If this is a new experience, work through some of the beginning Arduino tutorials to get a feel for the language.
  • NeoPixels aren’t the answer for every project. The control signal has very strict timing requirements, and some development boards (such as Netduino or Raspberry Pi) can’t reliably achieve this. This is why we continue to offer other LED types; some are more adaptable to certain situations.

Can I use NeoPixels for POV (persistence of vision) displays?

Not recommended. The refresh rate is relatively low (about 400 Hz), and color displays in fast motion may appear “speckled.” They look fine in stationary displays though (signs, decorations, jewelry, etc.). For POV use, LPD8806 strips (AdaFruit, disponible sur demande) will look much better (they have about a 4 KHz refresh rate).

How about for light painting?

Definitely! The slower movement used for photographic light painting doesn’t call attention to the limited refresh rate; the results look great, especially with a light diffuser.

Différents produits NeoPixels

NeoPixel Digital RGB LED Weatherproof Strip

Crédit: AdaFruit Industries

NeoPixel Digital RGB LED Weatherproof Strip is available in three different “densities”: 30, 60 and 144 LEDs per meter, on a white or black backing strip.

Crédit: AdaFruit Industries

Crédit: AdaFruit Industries

  • 30 LEDs per meter, white strip
  • 30 LEDs per meter, black strip
  • 60 LEDs per meter, white strip
  • 60 LEDs per meter, black strip
  • 144 LEDs per meter, white strip
  • 144 LEDs per meter, black strip

The approximate peak power use (all LEDs on at maximum brightness) per meter is:

  • 30 LEDs: 9.5 Watts (just under 2 Amps at 5 Volts).
  • 60 LEDs: 18 Watts (about 3.6 Amps at 5 Volts).
  • 144 LEDs : 35 watts (7 Amps at 5 Volts).

Mixed colors and lower brightness settings will use proportionally less power.

Important Things to Know About NeoPixel Strips

The product list continues below. But first...

  • NeoPixel strips are sold in one meter lengths. The 144 pixels/meter strips are always separate 1-meter lengths. For 60 and 30 pixels/meter strips, orders for multiple meters will be a single contiguous strip, up to a limit: 4 meters for 60 pixels/meter strip, or 5 meters for 30 pixels/meter strip.
  • For 60 and 30 pixels/meter strips, if purchasing less than a full reel (4 or 5 meters, respectively), the strip may or may not have a 3-pin JST plug soldered to one end. These plugs are for factory testing and might be at either end — the plug does not always indicate the input end! Arrows printed on the strip show the actual data direction.
  • Although these strips are flexible, they do not tolerate continuous and repeated bending. A typical application is architectural installations, where they can be curved around columns and then stay put. Repeated flexing (as on costumes) will soon crack the solder connections. For wearable use, either affix shorter segments to a semi-rigid base (e.g. a hat, BMX armor, etc.), or use the individual sewable NeoPixels shown later.
  • The flex strips are enclosed in a weatherproof silicone sleeve, making them immune to rain and splashes, but are not recommended for continuous submersion. Early 144 pixel/meter strips were not weatherproof, but the latest batches now include this feature.
  • The silicone sleeve can be cut and removed for a slimmer profile, but the strip is no longer weatherproof.
  • Very few glues will adhere to the weatherproof silicone sleeve. Using zip ties for a “mechanical” bond is usually faster and easier. The only two reliable glues we’ve found are Permatex 66B Clear RTV Silicone (not all silicone glues will work!) and Loctite Plastics Bonding System, a 2-part cyanoacrylate glue. The Permatex 66B silicone can also be used to seal the open end of a cut strip.
  • All strips are manufactured in 1/2 meter segments that are then joined into a longer strip. The pixel spacing across these joins is 2-3 millimeters different than the rest.

NeoPixel Shapes: Rings, Matrix, Shield and Strip

These ready-made shapes simplify many projects! Rings are perfect for jewelry, timepieces and navigation displays. Matrices work for bitmap displays and scrolling message signs.

All NeoPixel shapes can be chained (the output of one can connect to the input of the next) and are controlled from a single microcontroller pin.

Crédit: AdaFruit Industries

Crédit: AdaFruit Industries

Crédit: AdaFruit Industries

  • 12 NeoPixel Ring — 1.5 inch (37 mm) outside diameter. Max 5V @ 750 mA.
  • 16 NeoPixel Ring — 1.75 inch (44.5 mm) outside diameter. Max 5V @ 1A.
  • 24 NeoPixel Ring — 2.6 inch (66 mm) outside diameter. Max 5V @ 1.4A
  • 8x8 NeoMatrix — 64 LEDs total. The pixel spacing and board size allow seamless tiling. Max 5V @ 4A.

NeoPixel Shield for Arduino — 5x8 matrix plugs directly atop an Arduino board (can also be tiled separately if desired). If the overall brightness is carefully limited, can be directly powered from the Arduino. For most situations, connecting an external power supply is recommended. Max 5V @ 2.4A (the Arduino can only supply about 500 milliamps).

  • NeoPixel Stick — 8 NeoPixel LEDs on a rigid circuit board packed even more tightly than the flex strips. Solder pads on the back for connecting wires or breadboard pins (not included).

Current ratings shown are approximate maximums (all pixels on at peak brightness). Mixed colors and lower brightness settings will use proportionally less power.

Important Things to Know About NeoPixel Rings

  • When soldering wires to these rings, you need to be extra vigilant about solder blobs and short circuits. The spacing between components is very tight!
  • If using alligator clips, we recommend first soldering short jumper wires to the ring inputs and connecting the clips to those, for similar reasons. (Some of our tutorials and product photos do show alligator clips directly connected to the rings, but we’ve had a lot of experience using them.)

Single NeoPixels

Single NeoPixels allow maximum control over individual pixel placement (some are even sewable!), while bulk sheets are a more economical option.

Crédit: AdaFruit Industries

Crédit: AdaFruit Industries

Crédit: AdaFruit Industries

  • Flora RGB Smart NeoPixel (Version 2) — designed specifically for wearables and “soft circuits,” these NeoPixels can be sewn using our fil à coudre conducteur (traditional soldering works too). Sold in packs of 4.
  • Breadboard-Friendly Smart NeoPixel — accommodates pin headers with standard 0.1" spacing. Sold in packs of 4 (headers are sold separately).
  • NeoPixel Mini PCB — the smallest NeoPixel breakout boards have solder pads on the back. Sold in packs of 5.
  • WS2812 RGB LED with Integrated Driver Chip — bare NeoPixels for advanced users wanting to design their own custom boards and shapes. 10 pack. This is a surface-mount device, not recommended for novice soldering. For through-hole use, consider Breadboard-Friendly NeoPixels.

All individual NeoPixels can be chained from a single microcontroller pin, with the one caveat that WS2812 and WS2811 (e.g. Flora V2 and V1) types can’t be mixed in a single chain.

Each individual NeoPixel requires 60 milliamps max at full brightness. Mixed colors and lower brightness settings will use proportionally less power.

Source: NeoPixel UserGuide créé par Phillip Burgess pour AdaFruit Industries. Crédit AdaFruit Industries

Traduit par Meurisse D. pour

Traduit avec l'autorisation d'AdaFruit Industries - Translated with the permission from Adafruit Industries -

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