How to buy neopixel (ws2812b) strips for an Arduino or Raspberry Pi project

Neopixels can be purchased from many sources online. The best prices are often found at Asian deal sites like aliexpress.com.

The vast selection and number of variants of LED products in these catalogues can seem daunting especially for newbies looking for a deal. This post explains what the most common codes and numbers mean to help you identify 5V Neopixel products that are easily compatible with popular microcontrollers like Arduino and single-board-computers like Raspberry Pi.

Neopixel buying guide

The following sections cover different decision points that someone buying Neopixels will be faced with:

Pixels, strands, or rings

Neopixels are usually found a few different form factors:

  • individual pixels: these are usually mounted to a small circuit board barely larger than the pixel itself
  • strips: mounted to flexible strips of plastic tape
  • strings: individual pixels spaced apart with wires, like Christmas lights
  • rings: rigid circuit boards in circular and semi-circular shapes.

Choose what suits your project best. The Neopixel LEDs themselves are the same; this decision purely relates to what material they are mounted to.

Strips are the most common choice. They are flexible and usually come with a peel-off adhesive backing that isn’t usually very strong (hot glue often works better). Strips can be easily cut with scissors – all the way down to individual pixels, so this purchase is flexible to suit the needs of many projects.

Pixel density

Neopixel strips are typically priced by the number of Neopixels spaced along 1 metre of strip. Rings, strings, and individual Neopixels are simply priced based on how many pixels you’re buying.

When it comes to strips, common pixel densities found in online stores include: 30, 60, 90, and 144.

  • 30 pixels/m is a good choice for area lighting and creating an atmosphere
  • 60 pixels/m is a common general purpose choice that is suitable for many display applications as well where multiple strips are placed side-by-side to create a matrix display
  • 144 pixels/m feature nearly back-to-back pixels and are best suited for projects where a continuous band of colour effect is desired (for a continuous look, you will also need a good diffuser material to put over the lights to “wash” between the individual LEDs).

Generally strips are sold by the metre. The longest continuous strip that is generally available is 5m and comes packaged on a reel. Most strips come with a JST connector clip on each end of the individual strips that you purchase.

Driver chip (ws2812b)

Each individual pixel on a strip of neopixels has its own ws2812b integrated driver chip. The chip looks like a little black dot that can be seen somewhere “inside” each pixel (where exactly depends on the manufacturer).

The ws2812b “listens” on the control wire for instructions about what to do with its LED: what colour and how bright to make it.

The magic of neopixels is that each LED is individually addressable because each has its own chip. Every pixel “knows” its position along a string (even if its alone in a “string” of 1 pixel), and its colour and brightness can be controlled independently of any other pixels. Pixels can be programmed to appear to elegantly fade and transition between colours and intensities (at least as far as the human eye can perceive) because the control signal – which is usually 800kHz – updates the pixels many times per second.

The correct neopixel strips for most Arduino projects have 3-pins (or “wires” or “pads”): two for power (+ and -) and one for the control signal. Other types of LED strips can have more pins; 4 and 5 are common for other types of strips.

The order of the 3 pins doesn’t matter and can change depending on the manufacturer. Its important to always read the labels so you understand what each pin is for. The control signal is always directional, so strips are marked with an arrow to show the correct direction.

Voltage

Standard Neopixels are 5V. Its best to stick with the standard for most LED projects outside of large installations or commercial signage.

Both Arduino and Raspberry Pi operate at 5V. It can help reduce a project’s complexity when everything shares the same voltage! Note that while the Raspberry Pi is powered by 5V, its output pins are 3.3V. This is still enough to drive some pixels, or you can incorporate electronic components such as a level converter like the 74AHCT125 to bring output up to 5V.

Many varieties of strips and strings are 12V or more. There are also strips where the control line is 5V but the power lines are 12V or more. Read product details carefully. Again, for most Ardunio / Raspberry Pi or similar projects, its best to stick with classic 5V Neopixel strips.

Water resistance

Neopixel strips often to come in IP30, IP65, IP67, and IP68 varieties. The “IPX” refers to the degree of weather/water protection and is a global standard for electronics and other equipment.

See Wikipedia: IP Code for more information about IP Codes.

IP30 and below strips realistically can’t handle water so you should only use them indoors. IP65, IP67, and IP68 strands are water resistant. IP65 is usually covered in a plastic coating that is applied like hot glue to protect against splashes of water. IP67 and IP68 are inserted into a hollow rectangular plastic tube with a silicon cap covering each end. The tubes in IP68 strips are filled with a silicon or plastic sealant, making them the best bet for scenarios where the strip could be submerged in water.

For Neopixels in plastic tubes, extra silicon caps can be purchased on their own so you can cut the strips and make the ends watertight again. Hot glue is useful to squirt into the caps to ensure a watertight seal, especially around any wires.

LEDs

Many product listings will state the chip is a 5050 or SMD5050. This is the type of RGB LED that is found in neopixel strips as well as many other types of LED strips.

The RGB LED is actually made up of 3x LEDs: one each for Red (R), Green (G), and Blue (B) light. Different colours are produced by mixing different intensities of light. Some variants of these LEDs also include a dedicated white LED in addition to the 3x colours.

SMD5050’s are “dumb” on their own. It is the combination of a SMD5050 LED with a WS2812B integrated driver chip that makes it an awesome neopixel. Since many other types of LED strips use the SMD5050, if you see this somewhere in a product listing, double check to make sure that you’re getting a WS2812B driver with every pixel and that the voltage is 5V.

PCB Colour

PCB is an acronym for printed circuit board. In terms of Neopixel strips this refers to the flexible tape or strip itself that the pixels are mounted to. For rings, this refers to the hard plastic circuit board.

It is common for neopixel strips to be sold with a choice of white or black PCB. Other colours are manufactured but they are pretty rare. The PCB colour doesn’t make a difference when it comes to how a project works.

Other things to buy

You might want to consider a few other things to go along with an LED purchase:

  • Soldering equipment and supplies
  • Heat shrink tubing
  • JST Connectors (clips) with 3-pins/wires
  • AWG22 or AWG20 wire (note: these wire gauges can handle the power needs of smaller projects)
  • Power supplies (make sure 5V output!)

When purchasing a power supply take note of the amperage that its designed for and get one (or more..) that supply a greater amount of current than your project needs.

Adafruit has an excellent guide on Powering Neopixels:

If you need to power a lot of Neopixels, please be safe and do your homework. The current draw required can add up to potentially dangerous levels very quick. Erik Katerborg has written an excellent guide available as a PDF:

Installing CH340/CH34X drivers on MacOS to load sketches onto cheap Arduino clones

This post details how to get [most] cheap Arduino clones working with MacOS Sierra so you can upload sketches to them.

Many clones are not recognized “out of the box” because they implement their USB to serial interface with a CH340 chip designed by China’s WCH (http://www.wch.cn/) instead of the more costly FTDI chip found in genuine Arduinos.

Most sellers on “China deal sites” like Aliexpress.com are up-front about these chips and include “CH340” in their product titles and descriptions, though the implications of this design modification are not alway understood by purchasers.

The easy installation method covered in this post comes courtesy of one Adrian Mihalko. He has bundled the manufacturer’s latest Sierra-compatible CH340/CH34G/CH34X drivers for installation with brew cask. These drivers are signed by the OEM so its no longer necessary to disable Mac’s System Integrity Protection (SIP) feature.

Github: https://github.com/adrianmihalko/ch340g-ch34g-ch34x-mac-os-x-driver

I had no problem getting a Robotdyn Arduino Uno as well as another cheap clone running on a Mac with High Sierra.

Step by step

Prerequisite: ensure brew installed on your Mac. Verify its presence and version info by executing brew --version in Terminal.

To begin, install the drivers with brew cask:

brew tap mengbo/ch340g-ch34g-ch34x-mac-os-x-driver https://github.com/mengbo/ch340g-ch34g-ch34x-mac-os-x-driver

brew cask install wch-ch34x-usb-serial-driver

(Note: the above is only two commands. The first one runs long, so take care when copying and pasting.)

When the install completes, reboot your machine.

Next, plug your Arduino clone into a free USB port.

Using Terminal, verify that the device is recognized by listing the contents of the /dev directory and looking for cu.wchusbserial1420 or cu.wchusbserial1410 in the output:

ls /dev

For example, I found cu.wchusbserial1420 in the output when I connected my Robotdyn Uno.

Things are promising if you find a similar result.

The Arduino IDE ships with drivers for the Uno itself, and save for the CH340, my clones are otherwise fully Arduino compatible (note: some clones might require additional drivers, and/or a different Board must be specified in the Arduino IDE). For my clones, the following steps were all I needed to upload sketches:

  • Open Arduino IDE with a test Sketch
  • Select the correct port in Tools > Port (e.g. /dev/cu.wchusbserial1420)
  • Verify that the Tools > Board had “Arduino Genuino/Uno” selected
  • Verify/Compile the Sketch (Apple+R)
  • Upload the Sketch (Apple+U)

Done.

In particular, the Robotdyn Uno appears to be decently well made, it’s laid out to support all Arduino-compatible shields, and it comes on an attractive black PCB. Versus a genuine Uno, it uses a micro-USB port instead of a full size one and exposes the ATmega328P microcontroller’s analog 6+7 pins. The company makes a number of similarly slick-looking accessories on black PCB. Their store on AliExpress is: https://robotdyn.aliexpress.com/

Have fun with your cheap clones!