Arduino Stack Exchange
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Questions tagged [led]

An LED is a type of light source which is typically fairly small and has low power requirements.

An LED (Light Emitting Diode) is a semiconductor component which emits light (via electro-luminescence) when its forward voltage is sufficiently high.

In Arduino projects, small LEDs are commonly used as indicators. For example, it could be illuminated to show that a system is active/powered-on. LEDs typically operate at around 2-3 volts, requiring a current of 10-20 mA, meaning they can by powered directly from the digital output pins.

For safety, an LED should normally be used with a current-limiting resistor in series.

LEDs can also be used for other purposes, including general illumination, and in opto-isolators.

858 questions
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Pattern library for addressable LED strips

Is there any central place that we can get drawing pattern functions for the addressable LED strips like the once based on the WS2812B component? These are sold on the Adafruit site under the NeoPixel name. For example I know of a few pattern…
Dan McCreary
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Why are LED 0 and 1 on as well?

I was just playing around a bit and ran into a strange problem. LED 3, 5, 6, 9 and 10 are on, as intended. For some reason LED 0 and 1 are on as well. Can someone explain why this is happening? int ledPins[] = {3, 5, 6, 9, 10}; int pinCount =…
Kees Bakker
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Is it possible to run two for loops separated?

I have three funtion which describe the brightness of three LEDs. I want the seconde loop run 1 second after the first one and the third 1 second after the second one. One loop needs approximately 5 seconds. So basically I need to run three loops…
gamma
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The L LED Keeps Itself On

I am using a Arduino Uno 3 for line follower robot. However when I power the Arduino Uno, the L led is turned on and is never turned off. After a bit of searching I found out that the L LED is connected to pin 13. So I set the pin 13 to low but…
Redwanul Sourav
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Does the UNO R4 still have the standard on-board led on pin 13?

I need to add support for the UNO R4 (both models) for a library I'm maintaining. The library uses the LED on pin 13 as status indicator. I can't find any information whether that LED is still there on the R4 Minima and Wifi boards. The R4 Wifi has…
PMF
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LED sometimes don't turn off when a button is pressed

I'm still very new to this but I've put together some code that when a button is pressed, my servo runs continuously, a second button rotates it the other way and a third cancels everything. A red or green comes on depending on the rotation and this…
Nathan Cooper
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Hex to binary, LED blinking

I need to write a program that takes a user inputted HEX value and converts it to binary, then an LED blinks according to the number of 1's in the binary. For instance, if the value is 0xABC then there are number of 1's are 7 so LED will blink 7…
AleiusN
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Smooth breathing led

I am trying to make a simple breathing led circuit in which the intensity of the led varies between 0 and 255. I followed the Fade tutorial on the Arduino site, which gives me what I want, but I notice that the change in brightness is much more…
samzmann
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Best multiplexer for a led cube

I had fun making a 3x3x3 led cube. Now I want to build a bigger one. I'd like to find out the best IC for it. I've seen that some projects uses multiplexer like 4051 or 74HC595. I'd like to make it at least 8x8x8 (so the multiplexer has to easily be…
nkint
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How to get neopixel to fade colorwipe?

I'm trying to get a fade to happen when an LED turns on/off during the color wipe rather than just abruptly turning on/off. I'm not quite sure how to do this though. #include Adafruit_NeoPixel strip = Adafruit_NeoPixel(8, 3,…
user2252219
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Program stops working after a minute

I have made this small program to lighten up in sequence 8 LEDs, it starts fine, but it stops working after a minute or so and the first 2 LEDs stay permanently ON, its like the chip stoped, here is the code : // Initialize an array with all 8…
Electropepper
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ws2812b NeoPixel - how to address it? How Arduino knows the correct order of LEDS on the stripe?

How to get a One-Wire address of a given WS2812B pixel? I bought several of these, and I cannot make them light. On the other hand, when I connect the addressable LED strip made of these diodes, I have no problem controlling it. Here is my…
Adam Ryczkowski
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Will the arduino uno still work if I replace the onboard 16Mhz crystal with a 12Mhz crystal?

I have recently bought an arduino uno R3 (the type where the atmega328 is surface mount and not removable on a mainly blue PCB); the board has two crystals on it one for the clock for the USB serial and the other for the atmega328 clock. Suppose I…
Z.E.
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Do addressable RGB's need to be programmed differently from normal RGB's?

I bought these rgb's from Sparkfun, however I have no idea how to hook them up or how to program them. Obviously the data sheet was somewhat helpful, however I have no idea how the IC's in the LED's work themselves or how to control them separately,…
Perplexing Pies
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I'm looking for a way to emulate addressable LED strip using LED diodes in a custom arrangement

What I want to achieve is, I want to use my own LED pin diodes, customly place them into my sculpture and animate them. This is as I understand quite straightforward. The problem is the amount of wiring . I would want them to connect one another in…
Emir Uysal
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