The NeoPixel Digital RGB LED Strip (144 LED/m) is a really impressive product that will have you lighting up your room
in next to no time. The 144 individually addressable LEDs packed onto a 1 metre flexible water resistant strip, enables
a world of luminescent creativity that will blow your blinking Arduino friends away. The following tutorial will show you
how to create an immersive and interactive LED display using an Arduino UNO, a potentiometer and an accelerometer.
There will be a total of FIVE LED sequences to keep you entertained or you can create your own !
This tutorial was specifically designed to work with the 144 Neopixel Digital RGB LED strip with the ws2812B chipset. Here is a video of the project in action:
- Arduino UNO (or compatible board)
- Adafruit 5V 10A switching power supply (PRODUCT ID: 658)
- NeoPixel Digital RGB LED Strip (144 LED/m)
- 3-Axis Accelerometer Module
- Breadboard jumper wire
- 300 ohm resitor
- 4700uF 16V Electrolytic Capacitor (Jaycar Cat No. RE6243)
- 6 Pole PC Mount Pluggable Header (Jaycar Cat No. HM3106)
- 6 Pole PC Mount Pluggable Terminal Block Socket (Jaycar Cat No. HM3126)
- Double Sided mounting tape - 10m (Jaycar Cat No. NM2821) - optional
Before you start any LED strip project, the first thing you will need to think about is POWER. According to the Adafruit website,
each individual NeoPixel LED can draw up to 60 milliamps at maximum brightness - white. Therefore the amount of current required for the entire strip will be way more than your Arduino can handle.
If you try to power this LED strip directly from your Arduino, you run the risk of damaging not only your Arduino, but your USB port as well. The Arduino will be used to control the LED strip,
but the LED strip will need to be powered by a separate power supply. The power supply you choose to use is important. It must provide the correct voltage, and must able to supply sufficient current.
Operating Voltage(5V)The operating voltage of the NeoPixel strip is 5 volts DC. Excessive voltage will damage/destroy your NeoPixels.
Current requirements (8.6 Amps)OpenLab recommend the use of a 5V 10A power supply. Having more Amps is OK, providing the output voltage is 5V DC. The LEDs will only draw as much current as they need. To calculate the amount of current this 1m strip can draw with all LEDs turned on at full brightness - white:
144 NeoPixel LEDs x 60 mA x 1 m = 8640 mA = 8.64 Amps for a 1 metre strip.
Therefore a 5V 10A power supply would be able to handle the maximum current (8.6 Amps) demanded by a single 1m NeoPixel strip of 144 LEDs.
Arduino Libraries and IDE
Before you start to hook up any components, upload the following sketch to the Arduino microcontroller. I am assuming that you already have the Arduino IDE installed on your computer. If not, the IDE can be downloaded from here.
The FastLED library is useful for simplifying the code for programming the NeoPixels. The latest "FastLED library" can be downloaded from here. I used FastLED library version 3.0.3 in this project.
If you have a different LED strip or your NeoPixels have a different chipset, make sure to change the relevant lines of code to accomodate your hardware. I would suggest you try out a few of the FastLED library examples before using the code below, so that you become more familiar with the library, and will be better equipped to make the necessary changes. If you have a single 144 NeoPixel LED/m strip with the ws2812B chipset, then you will not have to make any modifications below (unless you want to).
NeoPixel Strip connection
The NeoPixel strip is rolled up when you first get it. You will notice that there are wires on both sides of the strip.
This allows you to chain LED strips together to make longer strips. The more LEDs you have, the more current you will need.
Connect your Arduino and power supply to the left side of the strip, with the arrows pointing to the right side of the strip.
Follow the ArrowsThe arrows are quite hard to see on this particular LED strip because they are so small, plus they are located right under the thicker part of the NeoPixel weatherproof sheath. I have circled the arrows in RED so that you know where to look:
NeoPixel Strip WiresThere are 4 wires coming from either side of the NeoPixel LED strip:
One red wire, one white wire, and two black wires.
It doesn't matter which Black wire you use to connect to the power supply (or Arduino) GND. Both black wires appear to be going to the same pin on the LED strip anyway. Use the table below to make the necessary NeoPixel Strip connections to the Arduino and power supply.
Large CapacitorAdafruit also recommend the use of a large capacitor across the + and - terminals of the LED strip to "prevent the initial onrush of current from damaging the pixels". Adafruit recommends a capacitor that is 1000uF, 6.3V or higher. I used a 4700uF 16V Electrolytic Capacitor.
Resistor on Data PinAnother recommendation from Adafruit is to place a "300 to 500 Ohm resistor" between the Arduino's data pin and the data input on the first NeoPixel to prevent voltage spikes that can damage the first pixel. I used a 330 Ohm resistor.
Powering your Arduino (USB vs Power supply)You can power your Arduino board via USB cable or via the LED strip power supply.
*** Please note: different power supplies will yield different accelerometer readings. I noticed this when changing the Arduino's power source from USB to LED power supply. My final sketch was designed to eliminate the USB/computer connection, hence I have chosen to power the Arduino via the power supply. The fritzing sketch below shows the Arduino being powered by a power supply only.
**WARNING: If you decide to power your Arduino UNO via a USB cable, please make sure to remove (or disconnect) the wire that goes to the the Arduino VIN pin. The GND connections remain unchanged.
Fritzing Sketch - NeoPixel strip connection
The potentiometer will be used to switch between the different LED sequences. When it reads zero, it will switch to
the next sequence in the list. It will jump right back to the beginning after the last sequence.
The potentiometer is also used to interact with the LEDs (e.g. controlling hue, brightness etc etc).
See the fritzing sketch below to add the potentiometer to this project.
Accelerometer connection (Y-axis)
The accelerometer makes the LEDs much more fun and interactive. We will only be using the Y-axis of the accelerometer in this sketch. By tilting the accelerometer from one side to the other, the LEDs react and respond accordingly.
The accelerometer is an essential component of the digital spirit level sequence. That's right ! You can use this sketch
to create your own spirit level. This digital version can also be used to measure angles !
Have a look below to see how to hook up the accelerometer to the Arduino. The Y-axis is connected to the Arduino analog pin 4. If you wanted to use the X and Z axis, connect them to one of the other available analog pins (eg. A3 and A5).
Let the fun begin !!Now that you have the Arduino code uploaded to the Arduino, and have made all of the necessary wire/component connections, it is time to turn on the power supply.
Sequence 1: Cylon with Hue controlThe LEDs will move from one end of the strip to the other. It should start off as a RED cylon effect. As you turn the potentiometer clockwise, the colour of the LEDs will change and move through the various colours of the rainbow. If the potentiometer reading gets back to zero (fully anti-clockwise), it will move to sequence 2.
Sequence 2: Cylon with brightness controlYou will see that the LEDs have turned off. The potentiometer readings correlate with the LED brightness. At the start of this sequence, the potentiometer readings will be zero, therefore the brightness will be zero (LEDs turned off). As you turn the potentiometer clockwise, the readings increase, and so will the brightness of the LEDs.
Sequence 3: Comet effect with Hue and direction controlThis is where the real fun begins. You control the hue of the leading LED with the potentiometer, however the LED will move along the LED strip as though it were affected by gravity. As it hits the end of the LED strip, it will bounce for a while and eventually come to a stop. The more you tilt the accelerometer, the greater the acceleration of the leading LED. The trailing LEDs have an interesting randomised glow, which creates the "comet" effect.
Sequence 4: FireStarter / Rainbow effect : Hue and direction controlThe initial colours of LEDs in this sequence creates a fire-like animation. As the leading LED moves along the LED strip, it appears to ignite the LEDs in its path, leaving a fire trail behind it. The fire effect is best when you turn the potentiometer clockwise slightly to introduce a small amount of yellow into the mix of colours. As you turn the potentiometer further clockwise, the fire trail turns into a pretty rainbow trail. The accelerometer affects the leading LED in the same way as the previous sequence.
Sequence 5: Digital spirit levelThis sequence was my original idea for this project, however I thought it would be nice to share some of the other cool effects I created on my journey of discovery. The idea was to make a digital version of a spirit level. I originally wanted the LEDs to represent a spirit level bubble that would "float" according to the vertical/horizontal position of the LED strip. However, as I played around with this sketch, I discovered that it could potentially be used to measure the angle of the strip relative to the horizon. The angle can be determined by the illuminated LED. If the strip is horizontal, the illuminated LEDs will be close to the middle of the strip, and their colour will be green. If the strip is vertical, the illuminated LEDs will be close to end of the strip, and their colour will be red. The colour is just an additional visual indicator.
Concluding CommentsThe NeoPixel Digital RGB LED strip is a lot of fun. The FastLED library makes for easy programming, and allows you to get up and running really quickly. 144 LEDs on a single strip means you have plenty of room for creative algorithms and lighting effects. Add a few sensors, and "pretty" quickly turns into "awesome" !!
This tutorial shows you how to control a "144 NeoPixel per metre Digital RGB LED strip" with an Arduino UNO. Feel free to share your own LED creations in the comments below.
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