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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.

9
votes
2answers
18k views

How to use a common anode 7-segment, 4-digit display?

Please take this question as an example to (my own) answer below. I've got an 7 segment, 4 digit LED display, but I don't have any idea on how to wire it. I don't understand the difference between ...
2
votes
2answers
7k views

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 ...
3
votes
3answers
2k views

Uno pin 13 LED mysteriously always ON at 0.14V unless pinMode OUTPUT

I upload a blank sketch: pin 13 LED is on. Why? I connect pin 13 to GND: it turns off until I remove the connection I connect multimeter between pin 13 and GND: measures 0.14V and LED turns off until ...
1
vote
3answers
474 views

Analog input draws current when Arduino is turned off

I am using a Arduino Pro Micro from SparkFun (similar to Arduino Leonardo, cpu: Atmega 32u4). It has a analog input: A0, which I use to keep track of the battery voltage in my battery powered project (...
17
votes
2answers
3k views

Can two LEDs attached to different pins share their resistor?

I'm designing an Arduino style board with built-in LEDs for several of the pins. To simplify assembly of the board and save on components, I was wondering whether it would be safe for those LEDs to ...
5
votes
1answer
955 views

Why does an LED sometimes flash when increasing brightness?

This is admittedly a cross-post from LED fade malfunction (random flash) but I can't get an answer on the Arduino forum. I was mucking around with some very basic code and I noticed that when ...
6
votes
2answers
2k views

Use Higher Resistance Than Instructed in a Circuit

I'm following the "Get Started with Arduino" Guidebook, and I'm at the part where pulse width modulation (PWM) is discussed. The instructions say to create a simple circuit with a breadboard, red ...
1
vote
3answers
1k views

Interfacing an ATtiny85 with MIDI via Software Serial

In order to finish a synth project that I'm working on I built a MIDI interface. To test it, I drew up some code which (is supposed to) light up an LED when any key is pressed. The light turns off ...
0
votes
2answers
133 views

Led on when not supposed to be

So I made a program that controls two LED's when two buttons are pressed, but one of the LED's comes on when the button isn't pressed. And what's weird is that if I literally move around the ...
0
votes
1answer
149 views

Arduino Mega 2560 LED is dim when powered from digital output

My circuit is a simple one, I am using an arduino atmega 2560. One 5mm red LED connected in series with a 150 ohm resistor. If I didn't make some kind of goof, a red LED has a voltage drop of 2 volts ...
3
votes
2answers
769 views

Need help with 2X3 matrix for braille

I'm an intermediate Arduino progammer, and I'm making an electronic braille display for my friend. You can think of this display as an array of 28x3 LEDs(one braille character contains a maximum of ...
6
votes
1answer
506 views

Choosing right Sleep state

I'm planning on building an LED clock, but I want it to be lit only when I press the POWER button on my remote control. Using an IR receiver, which Arduino sleep mode should I use to reduce the ...
3
votes
2answers
23k views

How to control 19 RGB LED strips with one arduino?

I need to light up 19 RGB LED strips, which it seems would require 19*3=57 PWM outs and 57 transistors. The transistors aren't an issue, but of course the 57 PWM's is. Even if I hacked the digital ...
3
votes
1answer
4k views

Arduino with WS2812 using Adafruit NeoPixel library fade in/out different patterns

Hey all I have been trying to figure out a way to random set patterns for my fade in/ out code below: int PIN = 3; int totalLEDs = 11; int ledFadeTime = 5; Adafruit_NeoPixel strip = ...
3
votes
5answers
579 views

Emergency Vehicle - Make two LEDs flash with buttons and a passive buzzer change sound

My Dad and I are just learning how to use my new UNO. We have learned how to make leds flash at the touch of a button. We have also learned how to make a passive buzzer sound at the touch of a ...
3
votes
3answers
12k views

Using external power supply to power leds on multiple pins (A0-A5)

I'm totally new to Arduino, and microcontrollers for that matter, so I'm having a hard time figuring out how to connect LEDs to multiple pins, but using a common external power supply... I've created ...
2
votes
1answer
2k views

Arduino and WS2812 RGB LED Strip “freezing”

I have been working on a project as a gift for my girlfriend for Christmas which involves some a bunch of standard "white" LEDs controlled by shift registers and darlington arrays, and also some RGB ...
0
votes
1answer
659 views

Advice on setting up a real-time audio equaliser

First time Arduino user here. We have a microphone set-up which feeds back loudly on particular frequencies and need an equalizer to (preferably automatically) detect spikes in particular frequency ...
6
votes
1answer
174 views

Working with multiplexers for constant voltage output

I'm working on creating a circuit where I'm trying to have the ability to switch multiple strands of LED rope on and off at a time using an Arduino and a multiplexer. With my current configuration, ...
4
votes
2answers
8k views

Receiving SMS by Arduino GSM Shield and control the LED with the content of this SMS?

I am using Arduino GSM Shield receiving SMS from an Android app. And the content of this SMS will control a LED. If the content of this SMS is not "off", the LED will be on and the content will be ...
2
votes
5answers
6k views

Stop Led's from blinking

My code: // Pin 13 has a LED connected on most Arduino boards. // give it a name: int led = 13; const int buttonPin = 2; // the setup routine runs once when you press reset: void setup() { // ...
1
vote
1answer
310 views

Using an Arduino for a Diorama Controller

Kind of new to the whole DIY electronics scene. I'm building a diorama for my son. It will include a length of track, a station, some other buildings, and scenery. It will be HO scale. The ...
1
vote
1answer
211 views

Sending a character 'A' through blinking led

How do i code to send a character 'A' to the arduino through a blinking led? i am doing a project about data transmission. i really need help&some guide. Material used are arduino uno r3,...
1
vote
3answers
81 views

LEDs Randomly smooth transitioning, accounting for black or how-to switch using HSV

I am stuck trying to get it not to account for black in RGB. My first instinct was to use the HSV color spectrum over the RGB rainbow but, the same code will behaves differently in HSV. If i could ...
1
vote
2answers
579 views

Why are MOSFETs only giving 8.1V for LEDs, not 12V?

I'm using three PWM outputs from an Arduino Mini Pro to drive the R/G/B parts of some strips of LEDs. The circuit is basically this: I've got a single 12V power supply, rated at 200W, to light the ...
1
vote
2answers
3k views

fading colors on a ws2812 strip

I have a strip of 7 leds. its ws2812. Im starting them on blue. Next I want them to do a slow fade into pink. So all Im trying right now is to increment r. I can get them to work one by one. But I ...
1
vote
2answers
964 views

Aduino 7 segment dice project

I am struggling with the code that I should write for my project. I finished my breadboard but I have never learnt programming before so I cannot write the program for the dice. My project is to make ...
1
vote
2answers
431 views

Arduino LED flashes with one button press

I want the LED to flash when I press the switch once, but it keeps flashing. I tried the idea of just lighting the LED and keeping it lit with just one button press, so I wrote: int led=13,button=12; ...
0
votes
2answers
531 views

Multiple buttons activating different methods for an LED strip

I am trying to use different buttons to activate different methods for an LED strip. However, when one button is pressed after another has been pressed, I want it to interrupt the first buttons method ...
0
votes
1answer
58 views

How to power multiple LEDs with a microcontroller [closed]

I currently have a "tiny" setup and want to put a few (~20-30) 0402 LEDs on a 1:87 scale car. My current setup is an ATtiny85 USB Mini Dev Board powered by a 90mAh 3.7V LiPo battery which is connected ...
0
votes
1answer
433 views

A LED should be lit when 'high'. Why does mine only burn with 'low'?

This is my followup question based on a serie of one project. Go my to profile to read 'm all. So I'm building something which includes a function that has a count (1000) that decreases over time, ...
0
votes
2answers
2k views

Controlling common anode RGB LED with PWM - Can individual colors be done w/o transistors?

I am using PWM (analogWrite) with a common anode LED. My previous experience is using a common cathode. My breadboard is as shown: simulate this circuit – Schematic created using CircuitLab ...
0
votes
2answers
533 views

Creating an Arduino Tic Tac Toe game

I'm trying to create a Tic Tac Toe game using the Arduino Uno. Since the Uno has a limited amount of pins to use, I am trying to see if there is a configuration that would make the project possible. ...
-1
votes
1answer
5k views

How to fix 12V RGB LED Strip connection to NodeMCU?

I am trying to hook 12V RGB Led Strip (LTROP SMD 5050 RGB LED Light Strip) to a NodeMCU unit. I know there are many different tutorials on this and I am very new to wiring and electric circuits. I ...