{"id":4124,"date":"2018-04-11T04:17:21","date_gmt":"2018-04-11T08:17:21","guid":{"rendered":"https:\/\/dronebotworkshop.com\/?p=4124"},"modified":"2023-04-12T12:53:19","modified_gmt":"2023-04-12T16:53:19","slug":"rgb-leds","status":"publish","type":"post","link":"https:\/\/dronebotworkshop.com\/rgb-leds\/","title":{"rendered":"RGB LEDS &#8211; Colorful Arduino Experiments"},"content":{"rendered":"\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-9571 size-full alignnone\" title=\"Download PDF\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2023\/04\/dbws-pdfdown.png?resize=64%2C64&#038;ssl=1\" alt=\"Download PDF\" width=\"64\" height=\"64\" data-recalc-dims=\"1\" \/> <a href=\"#Parts_List\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9563 size-full\" title=\"Parts List\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2023\/04\/dbws-parts.png?resize=64%2C64&#038;ssl=1\" alt=\"Parts List\" width=\"64\" height=\"64\" data-recalc-dims=\"1\" \/><\/a> <a href=\"https:\/\/youtu.be\/JpEFAXenTyY\" target=\"_blank\" rel=\"noopener\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9565 size-full\" title=\"View on YouTube\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2023\/04\/dbws-youtube.png?resize=64%2C64&#038;ssl=1\" alt=\"View on YouTube\" width=\"64\" height=\"64\" data-recalc-dims=\"1\" \/><\/a> <a href=\"https:\/\/s3.amazonaws.com\/download.dronebotworkshop.com\/RGB+LED+Sketches+-+DroneBot+Workshop.zip\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-9569 size-full\" title=\"Download Code\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2023\/04\/dbws-codedown.png?resize=64%2C64&#038;ssl=1\" alt=\"Download Code\" width=\"64\" height=\"64\" data-recalc-dims=\"1\" \/><\/a><\/p>\n<h2><span style=\"font-weight: 400;\">Introduction<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Light Emitting Diodes or LEDs make excellent and inexpensive indicators and displays for your electronics projects. \u00a0They are available in a variety of shapes, sizes and colors and can be powered by low voltages, making them ideal for battery powered devices.<\/span><\/p>\n<div class=\"youtube-player\" data-id=\"JpEFAXenTyY\"><\/div>\n<p><span style=\"font-weight: 400;\">RGB or Red-Green-Blue LEDs are a fusion of three LEDs in a single package. In addition to being able to emit their three primary colors RGB LEDs can be used to display virtually any color of the rainbow by fusing together combinations of their three colors.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">There are many different varieties of RGB LEDs, today we will look at two different types:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Standard RGB LEDs<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Intelligent RGB LEDs<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Standard RGB LEDs can be used as stand-alone devices while Intelligent RGB LEDs require a controller or microcontroller. An Arduino can be used with either type or LED.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4135\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-leds.jpg?resize=750%2C422&#038;ssl=1\" alt=\"RGB LEDs with Arduino\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-leds.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-leds.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Before we get started on lighting up our projects with RGB LEDs let\u2019s take a quick look at some color theory, this will help you understand how we can create a multitude of colors with just three primary ones.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Color Theory<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Color theory is the study of the mixing of colors to produce a specific visual effect. \u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Initial work on color theory was performed as early as the mid 1400\u2019s and early work with the science of color was undertaken by such luminaries as Leonardo da Vinci and Isaac Newton. \u00a0It was Newton who came up with the concept of the \u201ccolor wheel\u201d, a chart that describes the usage of \u201ccomplementary colors\u201d that is still in use today.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Most of the initial work with color involved sensory experiences rather than actual attributes of the physical world. \u00a0As a result much early work was subjective.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Modern color theory dates to the late 19th and early 20th century.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Additive vs. Subtractive Mixing<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">There are two types of color mixing theory &#8211; Additive and Subtractive.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4132\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-cmy-primary-colors.jpg?resize=750%2C422&#038;ssl=1\" alt=\"RGB and CMY Primary Colors\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-cmy-primary-colors.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-cmy-primary-colors.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Additive color models involve using primary colors that ADD together in order to produce the desired color. \u00a0As you might suspect the Subtractive color model works the opposite way, the primary colors are subtracted from one another to achieve the desired effect.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Additive color is used by devices that emit light, such as our RGB LEDs and the video screen you\u2019re probably reading this on now. \u00a0The RGB color scheme is the most popular additive color scheme, mixing Red, Blue and Green to create pretty well any color.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">One color that can\u2019t be created using the RGB additive color scheme is black. For this reason displays that use the RGB scheme are usually built with a black background, thus the total absence of red green and blue results in black.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Combining red green and blue at equal intensity results in white. \u00a0Some display LEDs have an additional pure white element to make the whites look better.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The most popular subtractive color scheme is Cyan, Magenta and Yellow or CMY. Subtractive colors are used on media that absorbs light, such as printed media. If you have a color printer the color cartridges it uses are cyan, magenta and yellow.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Many printers use the CMYK color scheme, the \u201cK\u201d stands for \u201ckey\u201d and represents the key color which is black. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">The CMY or CMYK color schemes cannot produce white, they are usually used on media (such as paper) that is white so the total absence of color results in white.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">If you want to learn more about color theory Wikipedia has some excellent articles on <\/span><a href=\"https:\/\/en.wikipedia.org\/wiki\/Additive_color\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">additive color<\/span><\/a><span style=\"font-weight: 400;\"> and <\/span><a href=\"https:\/\/en.wikipedia.org\/wiki\/Subtractive_color\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">subtractive color<\/span><\/a><span style=\"font-weight: 400;\">.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">As our LEDs will be using the RGB color scheme we will be focused on additive color today.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Color Temperature<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">If you\u2019ve been in the market for light bulbs for your home or for photographic purposes then you\u2019ve probably run into the term \u201ccolor temperature\u201d. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">Color temperature explains the difference between two light bulbs that are both described as white but which emit obviously different colors. <\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4130\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/color-temperature.jpg?resize=750%2C422&#038;ssl=1\" alt=\"Color Temperature\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/color-temperature.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/color-temperature.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Color temperature is measured in Degrees Kelvin.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The soft white light that you probably have in your living room or bedroom has a color temperature of about 2700 &#8211; 3200 degrees Kelvin.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The lights I have in my workshop are rated at 4000 degrees Kelvin and are distinctly \u201cwhiter\u201d than the ones in my living room.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The industrial lights used in a warehouse are usually about 6500 degrees Kelvin. And the lights favored by video studios are generally 5500 &#8211; 5600 degrees Kelvin as this matches the color temperature of sunlight at noon.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Interestingly light that we describe as \u201cwarm\u201d actually has a lower color temperature than light described as being \u201dcool\u201d!<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Basic RGB LEDs<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">We will be working with two types of RGB LEDs in our experiments. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">The first type is what I\u2019ll describe as the \u201cbasic\u201d RGB LED. essentially a fusion of a red, green and blue LED within the same package with an external connection to each of the three colors.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The other type, which I\u2019ll discuss in a bit, is the \u201caddressable\u201d or \u201cintelligent\u201d RGB LED, sometimes called a \u201cNeoPixel\u201d. <\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Common Anode &amp; Common Cathode RGB LEDs<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">The basic RGB led is available in two configurations &#8211; common anode and common cathode. \u00a0The configurations describe which leads of the three internal LED elements are tied together, as RGB LEDs have four leads.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4133\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-common-anode-and-cathode.jpg?resize=750%2C422&#038;ssl=1\" alt=\"RGB LED Configuration - Common Anode and Common Cathode\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-common-anode-and-cathode.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-common-anode-and-cathode.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Common cathode devices tend to be more popular as the cathode is the negative side of the LED and is usually connected to ground. This can sometimes be easier to integrate with microcontrollers although it is actually just as easy to use a common cathode device with a slight change in the programming.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Either way the LEDs will have four connections:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">The Common Connection (Anode or Cathode).<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Red LED.<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Green LED.<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Blue LED.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">These LEDs are available in many different package styles including conventional \u201cthrough the hole\u201d. Surface mount and LED strip lights consisting of several RGB LEDs connected in parallel with integrated dropping resistors.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The standard \u201cthrough the hole\u201d pinout is illustrated here:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4134\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-led-pinout.jpg?resize=750%2C422&#038;ssl=1\" alt=\"RGB LED Pinout Diagram\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-led-pinout.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-led-pinout.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Note that the connections can be identified by the lead lengths and their position relative to one another. If the leads have been trimmed the connections can be identified by observing the \u201cflat\u201d side of the case, this will be closest to the red connection.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Dropping Resistors<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">You can\u2019t just connect your power supply directly to the leads on the RGB led, doing so will quickly destroy the device. Like any LED the three elements within an RGB LED each require a dropping resistor.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">You will need a total of three dropping resistors, one for each LED element. Don\u2019t try and use just one on the common lead.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Note that you may have a prototype board or breakout board that contains both the RGB LED and the associated dropping resistors. In this case you can apply voltage directly to the device as the dropping resistors are already wired in.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">As with any LED to calculate the value of the dropping resistors you&#8217;ll need to know a few parameters first:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><b>Supply Voltage (<\/b><b><i>Vs<\/i><\/b><b>)<\/b><span style=\"font-weight: 400;\"> \u00a0&#8211; The voltage of your power supply.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>LED Forward Drop Voltage (<\/b><b><i>Vf<\/i><\/b><b>) <\/b><span style=\"font-weight: 400;\">&#8211; The amount of voltage the LED drops when inserted into the circuit.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>LED Maximum Current (<\/b><b><i>i<\/i><\/b><b>)<\/b><span style=\"font-weight: 400;\"> &#8211; How much current the LED can handle.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">The latter two parameters can be found on the specification sheet for the LED. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">Since we are using RGB LEDs there will actually be a separate set of parameters for each of the three internal LED elements. \u00a0Don\u2019t assume that all three elements have identical specifications, often you will find that the voltage drop of the red element is different than the other two elements.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Once you have determined what your three parameters are you can use them to calculate the value for your dropping resistor. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">We will use the following formula:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4131\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/led-dropping-resistor-formula.jpg?resize=750%2C422&#038;ssl=1\" alt=\"LED Dropping Resistor Formula\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/led-dropping-resistor-formula.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/led-dropping-resistor-formula.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Keep in mind that the value for current in the formula is in amperes but most LEDs have their current specified in milliamperes. So a rating of 30 milliamperes is specified as a value of 0.03 amperes.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">As an example the LED I used in my basic RGB LED demo in the hvideo associated with this article had the following ratings:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4136\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-led-specs.jpg?resize=750%2C422&#038;ssl=1\" alt=\"RGB LED Specifications\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-led-specs.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-led-specs.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Note that the red segment of the LED has a different forward voltage drop than the other two segments. So ideally you would use a different value for its dropping resistor.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Plugging the values into the equation and using 5-volts as my power supply voltage I arrive at the following values:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Red &#8211; 100 Ohms<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Green and Blue &#8211; 50 ohms<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">100 ohms is a standard resistance value whereas 50 ohms is not. You could use a 47 ohm or 56 ohm resistor for this one, I personally tend to choose the higher value.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Also note that you might want to reduce the current into your LED for many reasons. One is that if you are using a lot of LEDs it will decrease the requirements for your power supply. \u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Another reason is that some microcontrollers, especially cloned Arduino&#8217;s, may have difficulty supplying this much current and could be damaged. \u00a0This is why I tend to use higher values in my Arduino designs for LED dropping resistor.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">RGB LEDs with Arduino<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">Now it&#8217;s finally time to hook up some RGB LEDs to an Arduino and play with them!<\/span><\/p>\n<p><span style=\"font-weight: 400;\">In this experiment we will use an Arduino to adjust the intensity of the red, green and blue LED elements within our RGB LED. This should allow us to create just about any color we like (except black).<\/span><\/p>\n<p><span style=\"font-weight: 400;\">To control the levels we\u2019ll be using three potentiometers, these can be any style you like as long as they have values of at least 10k.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">I\u2019ve wired two RGB LEDs to the Arduino for this demo. One is a common cathode device and the other is a common anode RGB LED. \u00a0This way you can see how to drive both of them.<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4129\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/arduino-rgb-hookup.jpg?resize=750%2C422&#038;ssl=1\" alt=\"Arduino RGB LED Hookup Diagram\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/arduino-rgb-hookup.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/arduino-rgb-hookup.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">I used 220 ohm dropping resistor for all the LED segments but of course you can fine tune this and use different values for the individual segments. That would probably allow for more precise control of the light levels. Look at your LED specification sheet (you can probably find one on the Internet if you don\u2019t have one) and apply the formula we discussed earlier.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Note that we will be using pulse width modulation or PWM to control the LED segment brightness. If you need a refresher on PWM please see my article and video on \u201c<a href=\"https:\/\/dronebotworkshop.com\/dc-motors-l298n-h-bridge\/\">Controlling DC Motors with the L298N Dual H-Bridge and an Arduino<\/a>\u201d. In this article I used PWM to regulate the speed of some DC motors but it is also suitable for controlling LED brightness.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">As the Arduino Uno only has six pins that are capable of PWM we have used them all.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Arduino RGB Sketch<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">Once you get it all hooked up you\u2019ll need to run some code. Here is the sketch I used to get the job done:<\/span><\/p>\n<pre class=\"lang:default decode:true \" title=\"Arduino RGB LEDs\">\/*\r\n  RGB LED Demonstration\r\n  rgb-led-demo.ino\r\n  Demonstrates both Common Anode &amp; Common Cathode RGB LEDs\r\n  Uses three potentiometers for input\r\n\r\n  DroneBot Workshop 2018\r\n  <blockquote class=\"wp-embedded-content\" data-secret=\"IMG4qQhT8c\"><a href=\"https:\/\/dronebotworkshop.com\/\">Welcome to the Workshop!<\/a><\/blockquote><iframe class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" style=\"position: absolute; clip: rect(1px, 1px, 1px, 1px);\" title=\"&#8220;Welcome to the Workshop!&#8221; &#8212; DroneBot Workshop\" src=\"https:\/\/dronebotworkshop.com\/embed\/#?secret=tbgLKPHvm7#?secret=IMG4qQhT8c\" data-secret=\"IMG4qQhT8c\" width=\"600\" height=\"338\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\"><\/iframe>\r\n*\/\r\n\r\n\/\/ Define RGB LED pins\r\n\r\n\/\/ Common Cathode RGB LED\r\nint redPinCC = 3;\r\nint greenPinCC = 5;\r\nint bluePinCC = 6;\r\n\r\n\/\/ Common Anode RGB LED\r\nint redPinCA = 9;\r\nint greenPinCA = 10;\r\nint bluePinCA = 11;\r\n\r\n\/\/ Define Potentiometer Inputs\r\n\r\nint redControl = A0;\r\nint greenControl = A1;\r\nint blueControl = A2;\r\n\r\n\/\/ Variables for Values\r\n\r\nint redVal;\r\nint greenVal;\r\nint blueVal;\r\n\r\nvoid setup()\r\n{\r\n    \/\/ Setup LED pins as outputs\r\n    pinMode(redPinCC, OUTPUT);\r\n    pinMode(greenPinCC, OUTPUT);\r\n    pinMode(bluePinCC, OUTPUT);\r\n    pinMode(redPinCA, OUTPUT);\r\n    pinMode(greenPinCA, OUTPUT);\r\n    pinMode(bluePinCA, OUTPUT);\r\n    \r\n    \/\/ Setup Serial Monitor\r\n    Serial.begin(9600);\r\n}\r\n\r\nvoid loop() {\r\n\r\n\t\/\/ Read values from potentiometers\r\n\tredVal = analogRead(redControl);\r\n\tgreenVal = analogRead(greenControl);\r\n\tblueVal = analogRead(blueControl);\r\n\t\r\n\t\/\/ Map values to range of 0-255\r\n\tredVal = map(redVal, 0, 1023, 0, 255);\r\n\tgreenVal = map(greenVal, 0, 1023, 0, 255);\r\n\tblueVal = map(blueVal, 0, 1023, 0, 255);\r\n\t\r\n\t\/\/ Drive Common Cathode LED\r\n\tsetColorCC(redVal, greenVal, blueVal);\r\n\t\r\n\t\/\/ Drive Common Anode LED\r\n\tsetColorCA(redVal, greenVal, blueVal);\r\n\t\r\n\t\/\/ Write Color values to Serial Monitor\r\n\tSerial.print(\"Red: \");\r\n\tSerial.print(redVal);\r\n\tSerial.print(\" - Green: \");\r\n\tSerial.print(greenVal);\r\n\tSerial.print(\" - Blue: \");\r\n\tSerial.println(blueVal);\r\n\r\n}\r\n\r\nvoid setColorCC(int redValue, int greenValue, int blueValue) {\r\n  \/\/ Set Colors for Common Cathode Display\r\n  analogWrite(redPinCC, redValue);\r\n  analogWrite(greenPinCC, greenValue);\r\n  analogWrite(bluePinCC, blueValue);\r\n}\r\n\r\nvoid setColorCA(int redValue, int greenValue, int blueValue) {\r\n  \/\/ Set Colors for Common Anode Display\r\n  analogWrite(redPinCA, (255 - redValue));\r\n  analogWrite(greenPinCA, (255 - greenValue));\r\n  analogWrite(bluePinCA, (255 - blueValue));\r\n}\r\n<\/pre>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400;\">We start the sketch by defining the pins we used to connect both the common cathode and common anode RGB LEDs. These all need to be capable of PWM so if you are using a different Arduino then you\u2019ll need to change them accordingly.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Next we define the three analog inputs used for the three potentiometers. \u00a0We also define some integers to hold the red, green and blue values that we&#8217;ll be passing onto our LEDs.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">In the setup we set all of our LED pins as outputs. We also initialize the serial monitor where we will be displaying the current RGB values.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Before we discuss the loop let&#8217;s look at the two functions defined at the bottom of the sketch, <\/span><i><span style=\"font-weight: 400;\">setColorCC<\/span><\/i><span style=\"font-weight: 400;\"> and <\/span><i><span style=\"font-weight: 400;\">setColorCA<\/span><\/i><span style=\"font-weight: 400;\">. \u00a0These are the functions which drive our LEDs, one for the common cathode one and another for the common anode device.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Each function has three integer inputs, one for each of the three colors. \u00a0Both functions use the <\/span><a href=\"https:\/\/www.arduino.cc\/reference\/en\/language\/functions\/analog-io\/analogwrite\/\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">Arduino <\/span><i><span style=\"font-weight: 400;\">analogWrite<\/span><\/i> <\/a><span style=\"font-weight: 400;\">function to produce PWM signals on the respective pins.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">In the <\/span><i><span style=\"font-weight: 400;\">setColorCC <\/span><\/i><span style=\"font-weight: 400;\">function, which drives the common cathode RGB LED, we just pass the color values directly to the analogWrite function along with the proper pin number. It\u2019s as simple as that.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The <\/span><i><span style=\"font-weight: 400;\">setColorCA<\/span><\/i><span style=\"font-weight: 400;\"> function drives the common anode RGB LED. Since its common connection is to the positive voltage we need to send it the inverse of the signal sent to the common cathode LED. \u00a0We invert the PWM signal by subtracting the color value from 255 and we then use that value for the analogWrite function.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Now that you&#8217;ve seen the two LED drive functions we\u2019ll move back up to the loop.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">We begin the loop by reading the values of the three potentiometers using the<\/span><a href=\"https:\/\/www.arduino.cc\/reference\/en\/language\/functions\/analog-io\/analogread\/\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\"> Arduino <\/span><i><span style=\"font-weight: 400;\">analogRead<\/span><\/i><\/a><span style=\"font-weight: 400;\"> function. This will produce a value ranging from 0 to 1023 as the Arduino has an internal 10-bit analog to digital converter.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">We need to convert this to a value from 0 to 255 for our RGB values so we use an <\/span><a href=\"https:\/\/www.arduino.cc\/reference\/en\/language\/functions\/math\/map\/\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">Arduino <\/span><i><span style=\"font-weight: 400;\">map<\/span><\/i><span style=\"font-weight: 400;\"> function<\/span><\/a><span style=\"font-weight: 400;\"> to do the range conversion.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">After that it\u2019s a simple matter of passing the three color values to the two functions we looked at earlier, <\/span><i><span style=\"font-weight: 400;\">setColorCC<\/span><\/i><span style=\"font-weight: 400;\"> and <\/span><i><span style=\"font-weight: 400;\">setColorCA<\/span><\/i><span style=\"font-weight: 400;\">.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Finally we write the values to the serial monitor. And then we do it all over again.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Load the sketch into the Arduino (you can get all the code in the ZIP file linked in the References section of this article) and start playing with it. You should notice that both the common anode and common cathode RGB LEDs behave the same way and produce the same color.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">As you can see it\u2019s pretty easy to drive a couple of RGB LEDs with an Arduino. But how would you drive a lot of RGB LEDs? <\/span><\/p>\n<p><span style=\"font-weight: 400;\">If you wanted to drive a lot of RGB LEDs, like in an RGB LED strip, you could use three power transistors and an external power supply with the sketch we just looked at. \u00a0You\u2019d need the transistors as the output pins on the Arduino wouldn\u2019t be capable of sourcing that much current.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Of course that would allow you to drive as many RGB LEDs as your transistors and power supply can handle, providing that you wanted them all to display the same color.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">But what if you wanted to have a lot of RGB displays and have the ability to control them independently? It can be done, but in order to do it you\u2019ll need a different type of RGB LED.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Addressable RGB LEDs<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">There is another type of RGB LED that is very popular, the \u201caddressable\u201d or \u201cintelligent\u201d RGB LED. You may also see them referred to as \u201cNeoPixels\u201d which actually is a brand name for Adafruit&#8217;s line of addressable RGB LEDs.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">These addressable LEDs make use of an integrated circuit called a WS2812 which is an RGB LED controller chip. The LED\u2019s have this chip built-in to the same package.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The individual WS2812 RGB LEDs have four connections, just like the conventional RGB LEDs. Unlike the conventional LEDs they don\u2019t expose the individual LED elements, instead their connections are as follows:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><b>Data In<\/b><span style=\"font-weight: 400;\"> &#8211; An input from either the microcontroller or from the previous LED in a chain.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>5-Volts <\/b><span style=\"font-weight: 400;\">&#8211; The LED power supply. No dropping resistors are required as they are internal.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>Ground <\/b><span style=\"font-weight: 400;\">&#8211; The Ground connection.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>Data Out<\/b><span style=\"font-weight: 400;\"> &#8211; An output that is connected to the next LED on the chain.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">As you might of inferred from the pinout description the LEDs are connected in a chain, with the output of one LED driving the input of the next one.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">These addressable LEDs are available in a number of configurations &#8211; individual \u201cthrough the hole\u201d devices, surface mount devices, wired in LED strips and also wired in a variety of shapes and sized. They are also configured as wearable devices that can be sewn into clothing.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The pinout of the individual addressable RGB LEDs or NeoPixels is as follows:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4137\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-neopixel-pinout.jpg?resize=750%2C422&#038;ssl=1\" alt=\"WS2812 NeoPixel LED Pinout\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-neopixel-pinout.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-neopixel-pinout.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">If the leads on your LED have been trimmed you can identify the Data Out pin as being the one closest to the flat edge of the case.<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Controlling Addressable RGB LEDs<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">The addressable LEDs use a serial protocol with a very unique method of transmitting zeroes and ones. Instead of using low and high pulses there are a series of pulses transmitted with varying pulse widths.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">&lt;INSERT WS2812 LOGIC SIGNAL DIAGRAM&gt;<\/span><\/p>\n<p><span style=\"font-weight: 400;\">A logic 0 consists of a 0.35 microsecond high pulse followed by a 0.8 microsecond low pulse.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">A logic 1 is formed using a 0.7 microsecond low pulse followed by a 0.6 microsecond high pulse.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Each LED is sent a string of 24-bits, 8-bits each for the red, green and blue value. Each LED has an address that is self-established by its position in the chain.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">One thing that is obvious &#8211; timing is everything when it comes to using these addressable RGB LEDs. For this reason you must use a microcontroller or a dedicated controller to drive them as even a slight timing error can result in the wrong color or the wrong LED being addressed.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">An Arduino makes an excellent controller for these LEDs. There are a couple of great Arduino libraries for controlling these devices:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><a href=\"https:\/\/github.com\/adafruit\/Adafruit_NeoPixel\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">The Adafruit NeoPixel library<\/span><\/a><span style=\"font-weight: 400;\">. We will be using this library in our demonstration code.<\/span><\/li>\n<li style=\"font-weight: 400;\"><a href=\"https:\/\/github.com\/FastLED\/FastLED\/releases\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">The FastLED library<\/span><\/a><span style=\"font-weight: 400;\">. This is also another great library for driving addressable RGB LEDs.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Users of the Raspberry Pi and other small microcomputer boards will be sad to hear that these devices are not really suitable for controlling addressable LEDs (although you can get HATs for the Raspberry Pi that make this possible). \u00a0This is because microcomputer running high-end operating systems like Linux can\u2019t provide the precise timing signals required by these colorful devices.<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Addressable RGB LEDs with Arduino<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">So let&#8217;s gather together a few addressable RGB LEDs (NeoPixels) and use an Arduino to control them. <\/span><\/p>\n<p><span style=\"font-weight: 400;\">You can use individual LEDs or LEDs in strips and you can use as many as you wish, providing you have a suitable power supply to power them all up. \u00a0In my demonstration I used four \u201cthrough the hole\u201d NeoPixels which can be powered using the Arduino 5-volt output. Anything over 5 LEDs will probably require an external 5-volt power supply.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Keep in mind that in development mode you usually power the Arduino using the USB connection on your computer. If it\u2019s a USB-2 connection then the amount of current may be limited. You could always power the Arduino with an external supply or a 9-volt battery if you want to be on the safe side.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Here is how I hooked up my four NeoPixels to the Arduino:<\/span><\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4128\" src=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/arduino-neopixel-hookup.jpg?resize=750%2C422&#038;ssl=1\" alt=\"Arduino WS2812 NeoPixel RGB LED Hookup\" width=\"750\" height=\"422\" srcset=\"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/arduino-neopixel-hookup.jpg?w=768&amp;ssl=1 768w, https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/arduino-neopixel-hookup.jpg?resize=300%2C169&amp;ssl=1 300w\" sizes=\"(max-width: 750px) 100vw, 750px\" data-recalc-dims=\"1\" \/><\/p>\n<p><span style=\"font-weight: 400;\">In addition to the Arduino Uno and the addressable RGB LEDs you\u2019ll need an electrolytic capacitor and a 330 ohm resistor.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The capacitor needs to be at least 100uf, a bigger one would be even better. It serves to smooth the DC voltage and provide a current reserve for when the LEDs are being switched on and off. Make sure to observe its polarity!<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The resistor is used to protect the Arduino Data pin in case something goes wrong with one of the addressable LEDs.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">If you are using a strip of LEDs instead of discrete ones then they are already chained together so you just need to connect the power and data in pins. The strip will probably have an integrated resistor so you can eliminate that as well.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Make sure you wire up the LEDs correctly, putting them in backwards will reverse the 5-volt and Ground connections which is never a good thing!<\/span><\/p>\n<h3><span style=\"font-weight: 400;\">Arduino Addressable RGB LED Sketch<\/span><\/h3>\n<p><span style=\"font-weight: 400;\">Once you have everything wired up you&#8217;ll need some code to run to light up your world.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Our sketch will make use of the Adafruit NeoPixel library. The easiest way of installing this library is through the Library Manager in your Arduino IDE.<\/span><\/p>\n<ol>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Open the Arduino IDE (Integrated Development Environment).<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Click on the <\/span><i><span style=\"font-weight: 400;\">Sketch<\/span><\/i><span style=\"font-weight: 400;\"> menu at the top.<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Click on the <\/span><i><span style=\"font-weight: 400;\">Include Library <\/span><\/i><span style=\"font-weight: 400;\">selection. A sub-menu will open up.<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Select <\/span><i><span style=\"font-weight: 400;\">Manage Libraries<\/span><\/i><span style=\"font-weight: 400;\">. This will open the Library Manager<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Use the \u201c<\/span><i><span style=\"font-weight: 400;\">Filter your search<\/span><\/i><span style=\"font-weight: 400;\">\u201d box and type \u201cneopixel\u201d<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Look for <\/span><i><span style=\"font-weight: 400;\">Adafruit NeoPixel<\/span><\/i><span style=\"font-weight: 400;\">. When you find it click \u201c<\/span><i><span style=\"font-weight: 400;\">More info<\/span><\/i><span style=\"font-weight: 400;\">\u201d<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">Click the<\/span><i><span style=\"font-weight: 400;\"> Install <\/span><\/i><span style=\"font-weight: 400;\">button that appears<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">The Adafruit NeoPixel library will be installed<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">You may now close the Library Manager<\/span><\/li>\n<\/ol>\n<p><span style=\"font-weight: 400;\">The Adafruit NeoPixel library comes complete with a few sketches that demonstrate its use. The sketch we will be running today is an adaptation of the \u201c<\/span><i><span style=\"font-weight: 400;\">Strandtest<\/span><\/i><span style=\"font-weight: 400;\">\u201d sample sketch.<\/span><\/p>\n<pre class=\"lang:default decode:true \" title=\"Arduino NeoPixel Demo\">\/*\r\n  WS2812 RGB LED Test\r\n  ws2812-rgb-test.ino\r\n  Uses Adafruit NeoPixel Library\r\n  Functions from Adafruit NeopPixel Strandtest Examples\r\n  DroneBot Workshop 2018\r\n  <blockquote class=\"wp-embedded-content\" data-secret=\"IMG4qQhT8c\"><a href=\"https:\/\/dronebotworkshop.com\/\">Welcome to the Workshop!<\/a><\/blockquote><iframe class=\"wp-embedded-content\" sandbox=\"allow-scripts\" security=\"restricted\" style=\"position: absolute; clip: rect(1px, 1px, 1px, 1px);\" title=\"&#8220;Welcome to the Workshop!&#8221; &#8212; DroneBot Workshop\" src=\"https:\/\/dronebotworkshop.com\/embed\/#?secret=tbgLKPHvm7#?secret=IMG4qQhT8c\" data-secret=\"IMG4qQhT8c\" width=\"600\" height=\"338\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\"><\/iframe>\r\n*\/\r\n\r\n\/\/ Include Adafruit NeoPixel Library\r\n#include &lt;Adafruit_NeoPixel.h&gt;\r\n\r\n\/\/ Define Arduino connection pin\r\n#define LED_PIN 4 \r\n\/\/ Define the number of LEDs - change if necessary\r\n#define LED_COUNT 4\r\n\r\n\/\/ Create instance of NeoPixel class\r\n\/\/ Parameter 1 = number of pixels in leds\r\n\/\/ Parameter 2 = Arduino pin number (most are valid)\r\n\/\/ Parameter 3 = pixel type flags, add together as needed:\r\n\/\/   NEO_KHZ800  800 KHz bitstream (most NeoPixel products w\/WS2812 LEDs)\r\n\/\/   NEO_KHZ400  400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)\r\n\/\/   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)\r\n\/\/   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)\r\n\/\/   NEO_RGBW    Pixels are wired for RGBW bitstream (NeoPixel RGBW products)\r\nAdafruit_NeoPixel leds = Adafruit_NeoPixel(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);\r\n\r\nvoid setup()\r\n{\r\n  \/\/ Setup Serial Monitor\r\n  Serial.begin(9600);\r\n\r\n  \/\/ Initialize the LEDs\r\n  leds.begin(); \r\n  \/\/ Clear them all\r\n  clearLEDs();\r\n  \/\/ Show the result of clearing the LEDs\r\n  leds.show();\r\n  \r\n}\r\n\r\nvoid loop() {\r\n\r\n    \/\/ Print to Serial Monitor\r\n  Serial.println(\"Starting RGB LED Demo\");\r\n  \r\n    \/\/ Cycle through Color Wipe Examples\r\n    \/\/ Set colors to Red\r\n    Serial.println(\"Color Wipe - RED\");  \r\n    colorWipe(leds.Color(255, 0, 0), 200);\r\n    delay(1000);\r\n    \/\/ Set colors to Green\r\n    Serial.println(\"Color Wipe - GREEN\"); \r\n    colorWipe(leds.Color(0, 255, 0), 200);\r\n    delay(1000);\r\n    \/\/ Set Colors to Blue\r\n    Serial.println(\"Color Wipe - BLUE\"); \r\n    colorWipe(leds.Color(0, 0, 255), 200);\r\n    delay(1000);\r\n    \/\/ Set colors to Yellow \r\n    Serial.println(\"Color Wipe - YELLOW\"); \r\n    colorWipe(leds.Color(255, 255, 0), 200);\r\n    delay(1000);\r\n\r\n    \r\n    \/\/ Theater Chase Examples\r\n    \/\/ White\r\n    Serial.println(\"Theater Chase - WHITE\"); \r\n    theaterChase(leds.Color(127, 127, 127), 50);\r\n    delay(1000);\r\n    \/\/ Red\r\n    Serial.println(\"Theater Chase - RED\"); \r\n    theaterChase(leds.Color(127, 0, 0), 50);\r\n    delay(1000);\r\n    \/\/ Green\r\n    Serial.println(\"Theater Chase - GREEN\"); \r\n    theaterChase(leds.Color(0, 127, 0), 50);\r\n    delay(1000);\r\n    \/\/ Blue\r\n    Serial.println(\"Theater Chase - BLUE\"); \r\n    theaterChase(leds.Color(0, 0, 127), 50);\r\n    delay(1000);\r\n    \r\n    \/\/ Rainbow Examples\r\n  Serial.println(\"Rainbow\"); \r\n  rainbow(20);\r\n  Serial.println(\"Rainbow Cycle\"); \r\n  rainbowCycle(20);\r\n  Serial.println(\"Rainbow Theater Chase\"); \r\n  theaterChaseRainbow(50);\r\n\r\n  \/\/Finished\r\n  Serial.println(\"Loop Ended, Demo Finished!\"); \r\n  Serial.println(\".................................\");\r\n\r\n}\r\n\r\n\/\/ Function to set all LEDs off\r\nvoid clearLEDs()\r\n{\r\n  \/\/ Cycle through all LEDs\r\n  for (int i=0; i&lt;LED_COUNT; i++)\r\n  {\r\n    \/\/ Set color to zero which is off\r\n    leds.setPixelColor(i, 0);\r\n  }\r\n}\r\n\r\n\/\/ Fill the dots one after the other with a color\r\nvoid colorWipe(uint32_t c, uint8_t wait) {\r\n  for(uint16_t i=0; i&lt;leds.numPixels(); i++) {\r\n    leds.setPixelColor(i, c);\r\n    leds.show();\r\n    delay(wait);\r\n  }\r\n}\r\n\r\nvoid rainbow(uint8_t wait) {\r\n  uint16_t i, j;\r\n\r\n  for(j=0; j&lt;256; j++) {\r\n    for(i=0; i&lt;leds.numPixels(); i++) {\r\n      leds.setPixelColor(i, Wheel((i+j) &amp; 255));\r\n    }\r\n    leds.show();\r\n    delay(wait);\r\n  }\r\n}\r\n\r\n\/\/ Slightly different, this makes the rainbow equally distributed throughout\r\nvoid rainbowCycle(uint8_t wait) {\r\n  uint16_t i, j;\r\n\r\n  for(j=0; j&lt;256*5; j++) { \/\/ 5 cycles of all colors on wheel\r\n    for(i=0; i&lt; leds.numPixels(); i++) {\r\n      leds.setPixelColor(i, Wheel(((i * 256 \/ leds.numPixels()) + j) &amp; 255));\r\n    }\r\n    leds.show();\r\n    delay(wait);\r\n  }\r\n}\r\n\r\n\/\/Theatre-style crawling lights.\r\nvoid theaterChase(uint32_t c, uint8_t wait) {\r\n  for (int j=0; j&lt;10; j++) {  \/\/do 10 cycles of chasing\r\n    for (int q=0; q &lt; 3; q++) {\r\n      for (uint16_t i=0; i &lt; leds.numPixels(); i=i+3) {\r\n        leds.setPixelColor(i+q, c);    \/\/turn every third pixel on\r\n      }\r\n      leds.show();\r\n\r\n      delay(wait);\r\n\r\n      for (uint16_t i=0; i &lt; leds.numPixels(); i=i+3) {\r\n        leds.setPixelColor(i+q, 0);        \/\/turn every third pixel off\r\n      }\r\n    }\r\n  }\r\n}\r\n\r\n\/\/Theatre-style crawling lights with rainbow effect\r\nvoid theaterChaseRainbow(uint8_t wait) {\r\n  for (int j=0; j &lt; 256; j++) {     \/\/ cycle all 256 colors in the wheel\r\n    for (int q=0; q &lt; 3; q++) {\r\n      for (uint16_t i=0; i &lt; leds.numPixels(); i=i+3) {\r\n        leds.setPixelColor(i+q, Wheel( (i+j) % 255));    \/\/turn every third pixel on\r\n      }\r\n      leds.show();\r\n\r\n      delay(wait);\r\n\r\n      for (uint16_t i=0; i &lt; leds.numPixels(); i=i+3) {\r\n        leds.setPixelColor(i+q, 0);        \/\/turn every third pixel off\r\n      }\r\n    }\r\n  }\r\n}\r\n\r\n\/\/ Input a value 0 to 255 to get a color value.\r\n\/\/ The colours are a transition r - g - b - back to r.\r\nuint32_t Wheel(byte WheelPos) {\r\n  WheelPos = 255 - WheelPos;\r\n  if(WheelPos &lt; 85) {\r\n    return leds.Color(255 - WheelPos * 3, 0, WheelPos * 3);\r\n  }\r\n  if(WheelPos &lt; 170) {\r\n    WheelPos -= 85;\r\n    return leds.Color(0, WheelPos * 3, 255 - WheelPos * 3);\r\n  }\r\n  WheelPos -= 170;\r\n  return leds.Color(WheelPos * 3, 255 - WheelPos * 3, 0);\r\n}\r\n\r\n\r\n<\/pre>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400;\">The sketch starts by including the Adafruit NeoPixel library.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Next we define variables for the Arduino pin number we are using and for the number of LEDs we will be driving. If you are driving a different number of LEDs you must change this to match.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">We then create an object from the Adafruit NeoPixel library which we call \u201c<\/span><i><span style=\"font-weight: 400;\">leds<\/span><\/i><span style=\"font-weight: 400;\">\u201d. If you are using addressable RGB LEDs that are not using the WS2812 chip you may need to change a few of these parameters.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">In the setup we start the serial monitor, which will be used to monitor the progress of our sketch within the loop. We also initialize the LEDs and clear them all.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The loop relies upon a number of functions, all of them taken from the Adafruit sample sketch. They are as follows:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><b>colorWipe<\/b><span style=\"font-weight: 400;\"> &#8211; This function sequences the LED\u2019s one at a time in the color specified. You can also specify the delay between LEDs.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>theaterChase<\/b><span style=\"font-weight: 400;\"> &#8211; As its name implies it simulates the light bulbs commonly used on theater signs. You can pass it the color of the lights and the delay between them.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>rainbow <\/b><span style=\"font-weight: 400;\">&#8211; Displays all the colors of a rainbow, fading between subsequent LEDs. <\/span><\/li>\n<li style=\"font-weight: 400;\"><b>rainbowCycle<\/b><span style=\"font-weight: 400;\"> &#8211; Like the rainbow but distributes the colors in a different fashion.<\/span><\/li>\n<li style=\"font-weight: 400;\"><b>theaterChaseRainbow<\/b><span style=\"font-weight: 400;\"> &#8211; Combines a theater chase with a rainbow effect.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">The code also uses a function that I put in there, <em>clearLEDs<\/em>. This just sets the color of all of the LEDs to zero, which effectively turns them off. You need to run a \u201c<em>show<\/em>\u201d command to make it take effect.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The <em>clearLEDs<\/em> function is simple but it does illustrate how the LEDs are controlled. It uses a \u201c<\/span><i><span style=\"font-weight: 400;\">setPixelColor<\/span><\/i><span style=\"font-weight: 400;\">\u201d function which is one of the keys to working with the Adafruit NeoPixel library.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">The <em>setPixelColor<\/em> function has two parameters:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">The address of the LED. This starts at zero and increments for each LED in the chain.<\/span><\/li>\n<li style=\"font-weight: 400;\"><span style=\"font-weight: 400;\">The color value. This can be in hexadecimal or can be the three RGB values in decimal.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">By using the<\/span><i><span style=\"font-weight: 400;\"> setPixelColor<\/span><\/i><span style=\"font-weight: 400;\"> function followed by a <em>show<\/em> command you can control the color of any LED in the chain.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Load the sketch and run it. You should be greeted by a light display on your addressable or NeoPixel LEDs. The serial monitor will display the name of the function you are currently running.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">You might want to dim the lights and enjoy the show!<\/span><\/p>\n<h2><span style=\"font-weight: 400;\">Conclusion<\/span><\/h2>\n<p><span style=\"font-weight: 400;\">RGB LEDs are a great way of adding a bit of color to your Arduino projects. Whether you\u2019re just interested in adding a fancy status indicator or if you want to build a full fledged light show these devices make a great way to spice up your design.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">I\u2019d be curious to know what you build with RGB LEDs. Let me know in the comments below and also let me know if you have any questions about using RGB LEDs in your Arduino designs.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Here\u2019s to some colorful coding!<\/span><\/p>\n<p>&nbsp;<\/p>\n<div class=\"dbwspartsbox\">\n<h3>Parts List<\/h3>\n<p><em>Here are some components that you might need to complete the experiments in this article. Please note that some of these links may be affiliate links, and the DroneBot Workshop may receive a commission on your purchases. This does not increase the cost to you and is a method of supporting this ad-free website.<\/em><\/p>\n<p>COMING SOON!<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"dbwsresourcebox\">\n<h3><span style=\"font-weight: 400;\">Resources<\/span><\/h3>\n<p><span style=\"font-weight: 400;\"><a href=\"https:\/\/s3.amazonaws.com\/download.dronebotworkshop.com\/RGB+LED+Sketches+-+DroneBot+Workshop.zip\" target=\"_blank\" rel=\"noopener noreferrer\">Arduino Sketches<\/a> &#8211; All of the code used in this article in a ZIP file, just for you!<\/span><\/p>\n<p><a href=\"https:\/\/en.wikipedia.org\/wiki\/Light-emitting_diode\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">History of LEDs<\/span><\/a><span style=\"font-weight: 400;\"> &#8211; The Wikipedia entry on LEDs makes for interesting reading.<\/span><\/p>\n<p><a href=\"https:\/\/www.kitronik.co.uk\/blog\/led-resistor-value-calculator\/\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">LED Dropping Resistor Calculator<\/span><\/a><span style=\"font-weight: 400;\"> &#8211; A very useful utility by Kitronik.<\/span><\/p>\n<p><a href=\"https:\/\/learn.adafruit.com\/adafruit-neopixel-uberguide\/the-magic-of-neopixels\" target=\"_blank\" rel=\"noopener noreferrer\"><span style=\"font-weight: 400;\">Adafruit NeoPixel Guide<\/span><\/a><span style=\"font-weight: 400;\"> &#8211; A great article on using addressable RGB LEDs, also called NeoPixels.<\/span><\/p>\n<\/div>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>RGB (Red-Green-Blue) LEDs are versatile devices that can add color and functionality to your Arduino projects.<\/p>\n<p>In this article we\u2019ll examine the different types or RGB LEDs available to experimenters and see how to best use them with an Arduino. It promises to be a very colorful read!<\/p>\n","protected":false},"author":1,"featured_media":4135,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[9,5,90],"tags":[44,41],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/i0.wp.com\/dronebotworkshop.com\/wp-content\/uploads\/2018\/04\/rgb-leds.jpg?fit=768%2C432&ssl=1","jetpack_shortlink":"https:\/\/wp.me\/p74ClK-14w","jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/posts\/4124"}],"collection":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/comments?post=4124"}],"version-history":[{"count":3,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/posts\/4124\/revisions"}],"predecessor-version":[{"id":9980,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/posts\/4124\/revisions\/9980"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/media\/4135"}],"wp:attachment":[{"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/media?parent=4124"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/categories?post=4124"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dronebotworkshop.com\/wp-json\/wp\/v2\/tags?post=4124"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}