Adruino and neopixel LEDs have a tricky relationship?
It is not as black and white as you are thinking.
That is because many factors come into the loop while deciding the number of neopixels.
The good news is that you can control as many LEDs as you like. However, the rest of the decision is up to the Arduino model, RAM, I/O pins, Expanders, and of course the supply current to the input VIN. With each model comes it PWM that will be controlling the functionality of digital LEDs such as WS2812 aka "Neopixels".
Collect the Essentials
If you are browsing Arduino then you must already be familiar with the basics of the board. Along with why it is preferred!
Not only is Arduino simple to read and control. It also offers a simple computer plug and starts. You can download the software to run the codes and you have the LEDs doing what you want.
Moreover, Arduino is a complete board and does not require additional hardware to run it. The GPIO Pins, and Analogue Pins are attached to the microcontroller heart. Anyone can modify the board according to their requirements.
You get what that means right? You can control as many neopixel LEDs as you like with featured brightness and colors. However, keep in mind each board comes with its limitations.
Let’s look at what the Arduino has to offer before we jump to the LEDs. You will automatically be able to make sense of the number, brightness, and power supply to the battery!
Specifications of Arduino Board
The basic and most beginner friendly of all Arduino board types is the Arduino Uno. It is the easiest to modify and uses the simplest of codes.
Next, you can level up to Arduino modern board types like Mega, Due, and Teensy 3. With so many choices these days you can easily upgrade from Arduino Uno.
Just as you upgrade the board changes in the features also occur. Starting with Arduino Uno it offers,
14 digital (0-13) Pins
6 Analogue Pins
Volt Pin (Power Supply)
3.3 V, 5V
Four Pins 10(SS), 11(MOSI), 12(MISO), 13(SCK)
Transmit and Receive Data
Ways to Control Neopixel LEDs
There are several ways with which you an Arduino can control Nepixel LEDs.
The easiest method to determine the number of LEDs an Arduino can control is by checking the RAM/SRAM of the board along with the voltage input.
Apart from the number you can also determine the dimming, ON/OFF, sinking and sourcing of the neopixel lights.
I generally use these methods before I get myself the neopixels.
Let me tell you. So far these methods have worked like a charm!
· RAM: No multiplexing required.
· Digital Pins: Controls individual Neopixel LEDs.
· Multiplexing: Less brightness yet more Neopixels controlled.
· Power Supply: Limited power supply limits Neopixels number.
RAM determines the number of LEDs in a pretty simple way. The determinant factor is the RAM/ SRAM storage of the Arduino board no matter the type.
Neopixels are activated by feeding a data string into the first LED's data pin. Each LED reads the first 24 bits, sets the color with them, and then transmits the remaining bits. The length of this string is unrestricted.
For digital LEDs like neopixel also called ‘WS2812’ a standard Arduino Uno can control up to 600 RGB neopixels. As mentioned before it has a RAM of 2kb.
When compared to an Uno, which has only 2kb of RAM, a board with greater RAM, such as an Arduino Mega, which has 8kb of RAM, can operate up to 2400 pixels.
In either scenario, 3 bytes of SRAM are needed for every pixel. The Mega has 8K of SRAM available for use. That is divided between stack and other variables. However, even a UNO can easily handle 60 LEDs.
On the other hand, Teensy 3.1 includes greater SRAM memory and a faster processor (96 mHz vs. 16 mHz) (64 kilobytes vs. 8 kilobytes). Additionally, to achieve a high number of neopixels the LEDs configuration is important.
So, high neopixel configurations employing Teensy output the light in tandem. It also applies a variety of processor specific optimizations!
Digital Pins Method
The state of the pins determines the sourcing or sinking current. In the high state, the pins give out sourcing current, and similarly, in the low state or 0V give a sinking current. A board like Arduino only sources current according to this range. The current to the I/O pins should not exceed the maximum current amount specified.
Each pin is connected to an individual neopixel LED. So if there are 14 digital I/O pins in Arduino UNO then each LED receives a maximum current of 13. Though I highly recommend not to use the board at the maximum current. Thus, for optimal Arduino Uno results stay between 10 to 12 mA for individual neopixel LEDs.
It is important to note all that because let’s see if you have 60 neopixels and a 5V Arduino pin attached to each LED. How will you determine if it is enough to power? Also, how will you make sure that each neopixel LED is controlled uniformly?
An Arduino Mega 5v pin can deliver 5 volts. However, it can only deliver a few hundred milliamps at best. To power 60 pixels at their maximum intensity, a separate 5v power supply delivering around 3.6A is required. The 5v/4A supply ought to be sufficient!
I know what question is brimming in your head right now.
What if the pins are not enough? What if you want to light more neopixel LEDs?
Well, there is a solution for that as well. It is called multiplexing. Without the use of resistors that are added most of the time, you can increase the efficiency of your work.
For example, instead of individual LEDs now a single pin will control a set of neopixels. However, with a marvel like this, there is a catch. It costs you the brightness of your LEDs. You may control double than before but the neopixels will not be as brighter. Although that can be fixed yet it is a major drawback.
Depends on you though. Right? If you are unaffected by this flaw and consider there is already always a variation in RGB colors as many believe then you have the answer to your problem right here!
However, to light multiple LEDs you need to add the appropriate code to the software for each neopixel strip. Also, you have to update the LED pattern for the neopixel strip to make sure they light up exactly how you want them to!
Power Supply Method
The last method is most commonly used especially for neopixel LED strip forms. I personally prefer this method because it may come at a hefty price yet gives an experience like no other.
There is no complexity of pins and multiplexing. You can control a large number of strips for bigger projects. However, the saving grace is for smaller projects you will not notice the price hike!
The power supply method works with the help of a shift register. A memory space called a register can hold a binary integer. A bit is a name given to each unique binary number. A common shift register has an 8-bit register since it has 8 output pins. The status of each pin is represented by a matching bit.
Now say that you have a strip of 4000 that you want to run on Arduino mega. The only limit is the maximum power supply for which you need more external hardware components like resistors. So, it depends on the amount of electricity you supply to each light as well as the amount of power your computer uses.
Neopixels will use roughly 60mA of electricity when their brightness is adjusted to 255,255,255. When I use an Uno, Teensy, or Gemma to power the lights, I typically use 32 neopixels, and if I keep the maximum power for the R, B, and G power levels at 30, that means the maximum power neopixels can use is approximately 75 mA. The maximum power level should work with 60 neopixels if you maintain it at 15.
To find out if you can increase the power envelopment, you would need to experiment. Though there have been complaints about my neopixels being blinding even at power level 30!
Why do codes matter?
Have you heard of the several neopixel modes that you can enjoy in the neopixel lightsaber?
If you have then you are pretty close to guessing what is up our sleeve.
If you are going to use the neopixels for Arduino Uno to control the brightness of the LEDs for different modes then you must know the right codes. The Adruino software allows you to install the codes and run the neopixel programs smoothly without the use of peripherals or external components. Check out ‘NeoPixel Adafruit Library’ to find out more.
To satisfy your curiosity you can easily pick up codes for Blinking Mode, Fading Mode, Random Mode, Rainbow Mode, and more!
How to use Arduino?
If you are new to the use of Arduino neopixel LEDs then no worries. Follow the tutorial of YouTuber ‘So Much science’ and watch him break it down to you piece by piece.
Before you set up your system I would recommend going over the limitations of all the methods and testing them on a smaller scale. Get a feel before you try it on your final project.
Though Arduino is the simplest and the best microcontroller you can get your hands on. Hence the frequent use in the neopixel LED world. You can watch tutorials and run available codes on the internet effortlessly.
Lastly, for all those unsatisfied questions. Hit us up!
Frequently Asked Questions (FAQs)
How many LEDs can an Arduino Nano control?
A standard Arduino board offers 17 I/O pins excluding the reset, analogue, and RX/TX pins. So you can light 17x16= 272 LEDs.
How many NeoPixels can an Arduino Nano power?
If we talk about the neopixels then each neopixel offers 5V pins. Connect those to the 24 neopixels with one pin to the LEDs and the other 5V to the Nano.
How much power does a NeoPixel use?
A neopixel in a circuit draws up to 60 milliamps.
How much power does WS2812B use?
When powered at 5 V and set to full brightness, each RGB LED consumes about 50 mA. This implies that your LED strip may be drawing up to 1.5 A for every 30 LEDs that are turned on.
What is NeoPixel in Arduino?
Arduino is a microcontroller used to control the neopixel LEDs in various forms for example as individual LEDs or in the form of strips. Arduino use is increasing because of an increase in neopixel use due to its attractive aesthetics.
How many times can you program an Arduino?
As stated in the specifications, you can program boards including Uno and nano at least 10,000 times. There are fewer write-erase cycles for flash memory.
How many lines of code can an Arduino hold?
There are alternate driver packages that work on smaller and larger Arduino-like hardware, and "Marlin" firmware runs on an Arduino Mega or equivalent (256k/8k/16MHz) with a RAMPS shield. Marlin has roughly 280k lines of code. The vast majority of Arduino hardware lacks expandable memory.
Can you run NeoPixels at 3.3 V microcontroller?
5V neopixels are driven by 3.3V microcontrollers like in the Arduino board. A small number of neopixels are powered at this voltage. You can also store data though I recommend lowering the voltage closer to the microcontroller for ideal results.