Questions tagged [led]

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

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strip.clear() is not clearing/turning off the NeoPixel strip after resetting the ESP8266

In the code below which is running on a WEMOS D1 (ESP8266), a NeoPixel strip turns on 1 LED in red which moves left to right and then right to left whilst the board attempts to connect to Wi-Fi in the ...
Lachlan Etherton's user avatar
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1 answer
43 views

Same LED but different brightness on same PIN

I connected a led to pin 7 (with a small resistance to avoid burning it) and tried the code below, with and without pinMode as output void setup() { pinMode(7, OUTPUT); Serial.begin(9600); } void ...
Mah Neh's user avatar
1 vote
1 answer
96 views

Make two LEDs fade in and out with with different PWM values

I have two UV leds, one Vf 3.3V @ 150 mA and the second one Vf 5V @ 150 mA. I need a circuit to make them fade in and out alternatively, i.e., as one goes dimmer the other goes brighter and vice versa....
Rodrigo's user avatar
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2 answers
130 views

Just one more pin!

I have an Arduino project to control a motor's speed at 3 levels, indicated by 3 LEDs, so level 1 is speed 1 and LED 1, and so on for levels 2/3. Also, I added a low-battery voltage indicator to ...
Tito's user avatar
  • 111
-2 votes
1 answer
41 views

L LED on Arduino is constantly on and com is not detected

When I connect the Arduino to the computer, the L LED is constantly on and com is not detected. However, when I press the reset button, the L LED starts blinking for about 10 seconds and com appears. ...
Kerem Soylu's user avatar
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1 answer
58 views

blink a Grove - RGB LED Stick

I am trying to blink a Grove - RGB LED Stick (10 - WS2813 Mini 3535) with this code: #include "FastLED.h" int ledState = LOW; // ledState used to set the LED long previousMillis = 0; ...
dkin's user avatar
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1 vote
0 answers
202 views

How to use a DF Mini Player Busy Pin to start an LED Sequence?

I'm using a DF Mini Player with my Arduino Uno project I keep getting stuck on the same point - how to trigger my LED sequence. I discovered, through some google searching, that utilizing the BUSY ...
Ian's user avatar
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3 votes
1 answer
715 views

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 ...
PMF's user avatar
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2 votes
2 answers
589 views

Push button issues

I have been using https://wokwi.com/ to learn Arduino and I am having a problem that seems to be happening no matter what I do. I am trying to set up a push button and an LED. The end goal here is to ...
wgm's user avatar
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3 votes
2 answers
210 views

How to turn LEDs based on voltage readings?

I am trying to turn LEDs in an LED bridge based on the voltage reading from a power source. when the Voltage is zero nothing is ON and then the LEDs gradually turn ON as increase the voltage connected ...
Anwar Elhadad's user avatar
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247 views

LED doesn't completely turn off with digitalWrite(led, LOW);

When I was testing out a program I found a strange behavior of ESP8266. LEDs don't turn off completely in the first digitalWrite(led, LOW), just the brightness of the LED goes down, but it does turn ...
tatu101's user avatar
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2 votes
1 answer
254 views

ESP8266 seems to be killing a while loop

When i was testing out a program I found a strange behavior of esp8266 It seems to get out of a while loop even when there's no option of getting out on code I don't know if these are related but here'...
tatu101's user avatar
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1 vote
1 answer
124 views

Why does a simple LED Blink not work using mbed.h PWM and Arduino Nano BLE?

I have set up a very simple test program to blink an builtin LED using PWM. Following the mbed example and setting the period to 4 seconds (0.25 Hz) and duty cycle to 0.5, the expected behaviour is ...
Ivan Novikov's user avatar
1 vote
2 answers
386 views

How do I turn on 3 LEDs in a repetitive sequence where all three LEDs would then turn OFF when the push button used is released?

Basically, how do I modify my code listed below to turn ON each of the three LEDs one at a time in a repetitive sequence while keeping the push-button pressed? Red (3 sec), Yellow (1 sec), and Green (...
Mars's user avatar
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1 vote
1 answer
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Transmitting voice via VLC

The project I'm working on: Short-Range Coded Visible Light Communication System. Visible Light Communication (VLC) systems use light to transfer data between transmitter and receiver over short-range ...
Hussain's user avatar
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0 votes
1 answer
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fastLED help - special reinforcements needed

Hello help needed trying to get fastLED to start and stop at specific points on the strip, i have this nice fade animation but need to split the strip intov about 3 sections and have it run at ...
Acewindel's user avatar
-1 votes
1 answer
181 views

Why can't my four batteries (6V) can't power this circuit while usb 5v from arduino can?

I have this circuit And I want it to power all the led rgb (100 in total), I want to make a independent portable circuit, so I don't have to use the usb power. The thing is when I use this circuit it ...
RodParedes's user avatar
-1 votes
1 answer
143 views

RGB LED randomized colors and LDR fading at the same time

Im trying too make an RGB LED that keeps changing color's randomly, and makes the brightness fade at the same time with an LDR, yet I keep getting an error that says too many arguments to functions. ...
Sudras Elagor's user avatar
1 vote
0 answers
120 views

Problems using HC-SR04 with LED displays

I'm having problems using an HC-SR04 ultrasonic sensor in conjunction with an LED display module. The sensor appears to work fine when outputting values to the serial monitor, measuring distances up ...
Nicholas's user avatar
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1 answer
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I don't understand what's wrong with this code [closed]

int ledy = 5 ; int leds = 4 ; int ledk = 3; int button = 2 ; int count = 0 ; void setup() { pinMode(ledy, OUTPUT); pinMode(leds, OUTPUT); pinMode(ledk, OUTPUT); pinMode(button,INPUT); ...
gruesome's user avatar
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0 answers
516 views

ESP32 PWM with extended resolution doesn't work as expected

I have attached an RGB-LED to three output lines of the ESP32 and I'm trying to fade all colors independently. Since it didn't work with my code, I went back to the basic ESP32 ledcWrite_RGB sample ...
PMF's user avatar
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0 votes
3 answers
2k views

Interrupt on button press + debouncing

I want to have an interrupt function executed whenever a button is pressed. The button is connected to pin 2 and the GND. Therefore, the pin is turned to LOW whenever the button is pressed. In ...
user1584421's user avatar
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-1 votes
1 answer
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LEDs controlled by PHONE on ESP32

I am having doubts with a project I'm making. My project involves a sets of LEDs stripes, among which some are controlled from a smartphone, and some automated. The LED strips are connected to an ...
BruceWawe's user avatar
1 vote
2 answers
164 views

PWM with a TRANSISTOR on flexible LED filament

I would like to create a custom lighting, with PWM capability, powered from battery. I would like to use flexible led filaments, and since those consumes more than 40mA, I can't use them directly on a ...
BruceWawe's user avatar
1 vote
1 answer
96 views

Fading out a led with reed switch loop

I was hoping to get some help on the fading led which I am working on. For my project I need to have a led, which when it is placed next to a magnet, continuously shines, but as soon as it is taken ...
Igne's user avatar
  • 13
0 votes
1 answer
322 views

Simple FastLED sketch that crashes when led strip is long but not when its shorter

I have a pretty simple sketch that crashes, and crashes hard (Platform.io console says "Disconnected (read failed: [Errno 6] Device not configured)" and I need to power off/on the Arduino to ...
PaulM's user avatar
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0 votes
3 answers
99 views

Cannot read LED state

I am running into a problem on a very basic functionality. I want to read the state of an LED. I have confirmed that under the specified circumstances, the LED receives 1.9V. I try to read its state ...
user1584421's user avatar
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-1 votes
1 answer
55 views

Function call only works if called once

I have 3 LED chains which are all mapped to concentric rings. Each ring has a its own 2D array with the chain number & LED number. I have a function that is passed a ring array and then lights the ...
DrBwts's user avatar
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2 answers
172 views

Strange problems driving an Optocoupler (PC123) with a Nano

I'm having some strange issues getting a Nano to drive a PC123 optocoupler properly. What I'm trying to do: In the real world, I need to press a button ONCE, and have the device that I'm connecting ...
Pez's user avatar
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2 votes
1 answer
112 views

One LED in 4x4 matrix does not turn on [closed]

I'm an art student and absolute beginner to electronics/code - my broader goal is to learn how to control individual LEDs when there are many of them (like 64 or more even, so am learning about ...
Miso's user avatar
  • 21
0 votes
1 answer
106 views

Blink LED without delay with stepper motor

Based on a previous question I modified the script to use blink without delay. Unfortunately, it does not work, any idea why? I am using SparkFun RedBoard Plus, Qwiic LED Stick - APA102C, Adafruit ...
hsi100 's user avatar
0 votes
1 answer
181 views

Stepper motor and blink LED

I connected a LED stick to a stepper motor. Is it possible to blink the LED without stopping the motor rotation? I am using SparkFun RedBoard Plus, Qwiic LED Stick - APA102C, Adafruit Stepper motor - ...
hsi100 's user avatar
0 votes
1 answer
263 views

L LED keeps staying on

I am trying to get the Arduino to reboot my PC when it is off. Using the front panel header on the PC, I connected the power switch and PLED directly to the Arduino Uno as the header only outputs 5 V. ...
Ant's user avatar
  • 11
-2 votes
1 answer
221 views

LED blink patterns with multiple LEDs with millis() not using Delay()

I want to make LED blink patterns with multiple LEDs with the millis() function. I researched about it but did not find a perfect solution. I found one blog, but it is using a LED pin number array; I ...
coder's user avatar
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-1 votes
1 answer
68 views

Does an 5V 2.1 A will fit for this Led Schema?

Hello I would like to create an Arduino protoype with Led WS2182B. I currently have Arduino NANO (not UNO, like in this schema) 65 Led WS2182B = Which gives me 3.9 Amp of suply for full brighness (65*...
RodParedes's user avatar
-1 votes
1 answer
67 views

How to turn led lights off and on in order when below a certain photovalue?

I'm making a traffic light simulation with a photoresistor but it's not working properly. When the photovalue drops below a certain point ( a car comes by) a peeping sound should play for a second and ...
Mansour's user avatar
1 vote
1 answer
94 views

Apparently the photoresistors don't pass the input at the leds

I am making a school project where i need to create a parking loot in tinkercad. Me and my mate tried to use a bunch of photoresistor that worked as a sensor. No light = car = red led; light = no car =...
Visioli's user avatar
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1 vote
0 answers
203 views

FastLED changing colour at holding state

Basically make a code to guide users through a box breathing exercise (breath in for 4 seconds, hold for 4, release for 4, hold again for 4, repeat) to help relax them. Right now my code is running ...
entirelyreverse's user avatar
-2 votes
1 answer
119 views

Powering LEDs with Arduino uno 5v

I'm working on the sound reactive led lamp as my first project and have slightly different materials to start with. First I'd like to simply learn to power the LED strip. from https://www.youtube.com/...
Ellie S's user avatar
0 votes
1 answer
82 views

How do I keep one function continued until a variable is completed?

The code's purpose is to change from one led to another if the LDR detects a certain level of light for a given time. Currently, since I cannot wait 5 minutes to complete one circuit, each LED should ...
Zoe Melck's user avatar
1 vote
0 answers
101 views

LED brightness variations

I'm using two different types of code and noticing that in the first set up the last LED is dimmer than the rest. Then in the second set up, the first LED is brighter than the rest. I would like to ...
Genma's user avatar
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5 votes
1 answer
1k views

How arduino PORTB pins are addressed if I want to access them with pointer?

So Let say I want to access Digital Pin 13. Thats port B pin. Is there an memory address associated with this pin 13 of Arduino Uno r3? How Port B pins are addressed with corresponding pin numbers ...
user786's user avatar
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1 vote
1 answer
156 views

Can't figure out why what I'm trying to do isn't working. Trying to light up a RGB with buttons with AnalogWrite

DISCLAIMER : I have just started Arduino, like 2 days ago, I've been following some tutorials on YouTube, and I tried to do this myself, but I can't figure out why it isn't working, can't find what I'...
salfysox's user avatar
2 votes
2 answers
761 views

Toggle button switches through case statements with button debouncing

The overview of my code is that I want a toggle button to be pushed and each button push will move the code to the next case statement. In each case statement, there will be different LED functions. I ...
Myles's user avatar
  • 73
2 votes
2 answers
79 views

Trying to keep my main code running unless an input is LOW for a certain amount of time

I have code that creates a sequential signal with 4 LEDS. It cascades to the right. This works when I hold down the input button. What I need help with is having the code run exactly the same when ...
Myles's user avatar
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1 vote
2 answers
220 views

How exactly do Bicycle LEDs work? (Arduino Project)

Table of contents: What I want to achieve Problem I'm facing What I've tried Possible Hypotheses What I want to achieve Hi guys, I’m working on a DIY LED Light project to install on my bicycle, ...
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0 votes
1 answer
700 views

Are resistors necessary for 8x8 LED matrix?

I was following the official tutorial of LED matrix integration and couldn't figure out why there is no resistor. I assumed there are built-in resistors in the LED matrix, so I did an experiment by ...
Weihang Jian's user avatar
3 votes
2 answers
274 views

Why does the official tutorial for LED matrix scanning writes column pin twice?

I was following the official tutorial and confused by the source code. Arduino Official built-in example: RowColumnScanning // when the row is HIGH and the col is LOW, // the LED where they meet turns ...
Weihang Jian's user avatar
3 votes
1 answer
755 views

How do I run 4 LEDs sequentially based off of a push button input?

I am trying to create a program that runs 4 LEDs sequentially while also being able to do other things with different inputs and outputs. Because of this, I am using the millis function and not the ...
Myles's user avatar
  • 73
1 vote
1 answer
170 views

Breathing LEDs on single PWM pin?

I'm doing a project which is essentially a lighted cube, that communicates status through different colors, where I get this ides [it][1] (having code). So when the light goes below a certain level it ...
Kathberny's user avatar

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