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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37 views

Sound sensor & LED delay in home automation project [on hold]

I hope I can resolve these 2 things: I have arduino project - House automation I need to adjust few things: milis instead delay for example LED via ldr and PIR motion sensor - because when I use ...
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47 views

Random lighting for 18 pin LED

I am trying to write code so that 18 LEDs will light up randomly except 2 of them light up together. Am I using random wrong? I initialized it to make the random number random. Here is my code: ...
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1answer
55 views

Insane heat development with ESP8266

I have a ESP8266 on a Wemos D1 mini board. Simple "Rainbow with FastLED" animation. Shouldn't do much but the board gets so hot I can't touch it and it drains a 2500mAh battery in less than an hour. ...
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1answer
23 views

Losing top brightness when using tip120 and PWM with 70w LED panel

I have been experimenting with pwm dimming using TIP120 on various high powered LED's, and have noticed a marked drop in the top level brightness compared to original connection without the tip 120 in ...
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3answers
51 views

How to keep the regulator cool while battery powering the arduino and accessories?

I'm trying to build a battery operated hand lantern. It has the Arduino, an MPU6050 accelerometer, and 4 APA106 (WS2812B-like) LEDs. If everything's powered through the Arduino's 5V pins, that's 80mA ...
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24 views

UV sensor help!

I am creating a uv sensor. The sensor detects a certain amount of UV light and turns on the respective light (eg uv of 1-3 turns on a blue light). However I am getting an error: "expected primary-...
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2answers
38 views

Make a set LED dimming schedule?

I'm trying to made the LED's go from minimum brightness to maximum brightness and back to minimum in 2.55 seconds. I really don't know where to begin. I have the following basic code for making it ...
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1answer
34 views

Nth-Light LED Strip power connections

Based on this question https://forums.adafruit.com/viewtopic.php?f=47&t=140255&p=693992&hilit=nth#p693992 for Nth-Light Narrow LED Flexible Strip Light (https://www.adafruit.com/product/...
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2answers
56 views

Arduino Nano LED not working

I am just starting with Arduino and was trying to make the LED example work. I changed the script as follows to keep the LED on: #define LED_PIN 12 #define LED_RX_SIG LED_BUILTIN void setup() { // ...
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1answer
35 views

Problems with controlling LED with soil moisture sensor

I'm a beginner at Arduino. I have a soil moisture sensor and I mapped the lowest and highest moisture value to a value in between 0 and 100. What I was trying to do was if the value was less than ...
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1answer
36 views

One Led and 2 buttons [closed]

I need to switch on led with pushing button number 1 , and during 3 seconds it should stay on, and if I push button number 2 during this 3 seconds led should turn off. In other case after 3 seconds ...
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0answers
9 views

Communication using two HC05 modules

I'm working on a project that consists of sending data from flex sensors from a master Arduino to a slave arduino that uses that data to control servo-motors. I am trying to start slow and just ...
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1answer
42 views

LED array flashes once before being lit

I've built this simple Arduino controlled led-array. The Arduino sets a 5v pin on a relay to connect the high current power supply to a led array. However, just before the led array is being fully ...
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1answer
47 views

Locate devices that can move among multiple connections [closed]

I don’t know if this is even doable, but the idea is to have a large board with many (500+) locations where I objects can connect, each object having a single LED, and be able to illuminate the LED on ...
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1answer
126 views

LED not blinking when using a transistor

I want to control an led using a transistor. The led gets it‘s power from an external 5v dc power supply. For the transistor I use an 1kΩ base resistor. The transistor is a BC547C (npn). The ...
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2answers
55 views

RGB LED Mode toggle - Trying to avoid using main loop()

I'd like to start by saying that I have only been dabbling in electronics (not just Arduino) for about 3 days now. I am trying to write a sketch which changes an RGB LED when a push switch is pressed....
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32 views

LED doesn't turn on as specified on code State Machine

This is the question from the homework I'm doing "Design and implement a state machine with a single button to turn on and off two LEDs The first LED should be turned on and off with a quick press of ...
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1answer
37 views

LED dimmer not fading out

I'm trying to make an LED go from no brightness to max and back down on a loop and I've encountered a problem I can't seem to crack. The LED will go to maximum brightness steadily as it should but ...
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1answer
46 views

Controlling a 5m LED strip with a Nano or Uno

I'm wanting to control a 12V LED strip (5m, 60 LEDs per meter) with a Nano or Uno. I know from Adafruit that I'll need some power transistors but I'm not sure that I have the right type. I have 6 ...
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1answer
52 views

Troubleshooting WS2812B LED strip

I am doing a project for my master thesis and I have 6 stripes of WS2812B LEDs each one containing 77 LEDs. I finished the design and now want to turn them on. I used an old power supply to power it, ...
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1answer
58 views

Red LED not turning off on Adafruit Circuit Playground Classic

When using the traditional Blink example program, the light blinks as expected. Even when writing from scratch digitalWriteing pin 13 to high and low repeatedly works fine. The problem is when I try ...
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1answer
44 views

Measure duration of LED pulse and conditional serial print [closed]

Casual Arduino user with some programming experience here. I am trying to build a system to integrate with another board which switches relays based on serial data received. I have a status LED that ...
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1answer
21 views

Press one button then another?

Let's say we have two buttons - button 1 and button 2. What I need to do is to do something (like turn LED on) when button 1 is press, then button 2 is pressed. I can do it realy simple by just using ...
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1answer
24 views

I am not able to set the correct configuration of sound module

I have been trying to make sound reactive LED lights but my sound module is detecting only very close voice the LED react only when I press it to the speaker with my hands I have tried to set the ...
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0answers
32 views

On the LEDs WS2812C

I've got a few questions about these LEDs (WS2812C). According to what I understand in the data sheet, they are adressable RGB LEDs with 4 pins: VCC, GND, DIN,DOUT. I'm working on a project that is an ...
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63 views

Programming POV Display for Arduino

I can maybe work through a php/sql and css/html method of making a website to convert an image to code, but that is currently a time consuming method (which i will be taking the challenge if doing ...
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1answer
36 views

Serial input help

Hey guys I have a LED strip with 6 LEDS (I control these through Kinect & processing. It sends 1,2,3,4,5,6 to Arduino. This seems to work fine.) In Arduino LED0,LED1,LED2,LED3,LED4 work ...
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2answers
34 views

Receive Signal from different circuit

I am an mid experienced Programmer but I have no clue about electronic circuits. I want my Arduino to do sth if he gets a signal from an external source. The external source has 5V and is 0V or 5V and ...
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1answer
22 views

Output pin low used to complete 12V LED circuit?

I have a project that (in part) will drive 3 LEDs where the LED anodes are at 12V. The thought is to drive each LED by connecting each cathode to a 650 ohm resistor, and connect that to an Arduino ...
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2answers
37 views

How many Amps can a Nano Arduino hold for LED project

I'm really new at this, and here is my doubt. What if I need to light 120x WS2812B (5v)LEDs (link: LEDs) using an Arduino Nano? if it takes 60 mAh each pixel, the total amount needed should be around ...
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1answer
22 views

Using an Android bluetooth terminal to change preset states on 8x8 LED matrixes

I'm trying to create eyes for a project, and while I have been able to properly program the different expressions, and have them triggered by commands from the COM3 terminal, I have not been able to ...
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1answer
50 views

Using 18650 batteries with a 3.7v to 5v boost converter [closed]

I'm looking to set up a 1-meter strip of WS2812B LEDs (60 LEDs) with an off-the-shelf RF LED controller with a remote. The LEDs want a 5V supply - I've tried running them off 3.7v but the colour ...
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1answer
43 views

Is SPI a good way to connect two rfid modules on separate arduino boards?

RFID access control I have two separate rfid projects on separate arduino, the first project requires 2 minutes of contact between the tag and the reader after which it turns the LED on. the second ...
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1answer
37 views

Why can't I switch off the LED immediately using this sketch?

I hope the LED can fade out a period of time. Also, I hope I can switch off the LED immediately when it is fading, but I only can fade out. const int buttonPin = 2; const int ledPin = 9; const int ...
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1answer
64 views

Is there a way to have the LED switch on after 10 readings or say a minute?

I am using Arduino for a RFID project where the LED must switch on after either 12 readings of the tag or 2 minute, the tag reading happen every 10 seconds. I can't seem to figure out a way to have ...
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1answer
49 views

PWM Control, How to stop LED from Flickering?

What is required is controlling the brightness of an LED using both Buttons and a Potentiometer, Button A: Increase Button B: Decrease /Dim Potentiometer: Increase and Decrease, This however must ...
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1answer
61 views

AtTiny analog read always 1023

I am trying to replicate Low power LED firefly project. So what I'm trying to do is to do an analog read from a LED, to detect light. To simplify it a bit, I am using different pins and different leds ...
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4answers
692 views

changing state of an LED using a pushbutton leads to unstable result

I am trying to run this code: const int buttonPin = 7; const int ledPin13 = 13; int buttonState = 0; int lastButtonState = buttonState; bool flag = true; void setup() { // ...
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2answers
64 views

How to hook up led matrix 1088AS to a PCA 9685 servo controller? there is a way? [closed]

I'm confused about the pinout, I can't figure out which physical pin of 1088as red led matrix must to hook up to the PCA9685, if there is a way to do this I found this image the final target is to ...
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2answers
113 views

LED on same Pin as Toggle Switch, not illuminating

I am trying to do something I think should be relatively simple. I would like to read an input from a toggle switch, and have a red 5mm LED indicate the state of the switch. Rather, however, than have ...
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0answers
30 views

Using a 48 characters char[] for PROGMEM

I am trying to create a charliplexed display of 6x8 LEDS using a Arduino Nano with the ATMega328p chip. Because of the limited storage I am trying to use PROGMEM. I did my research and found some ...
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1answer
63 views

MAX7219 and Arduino

I am getting started in running this 8x8 led on an Arduino. Regardless of which tutorial sketch I attempted, I never got a scrolling text that I expect. What happens seems to be only a single (out of ...
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1answer
41 views

connection of led with dht and code combination

Hi again? I saw my last question did not come out well, so let me rephrase it. Ideally, my project is composed of 3 sensors: 2 dht-22 sensors and an mq-7 sensor. For the dht22 sensors, I am using ...
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2answers
59 views

7 LED Number Display

I need to write a string of number such as 1234567 on a 7 LED display. For example 1 will be lit up on display for 0.5 seconds, it will turn off then 2 will light up and so on. In the end I need to ...
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0answers
92 views

Multiple Servo motors with an ultrasonic sensor

I am building a robot arm with 6 servo motors that works with an ultrasonic sensor. The purpose of the program is when an object is detected at 20 cm (fixed position) from the sensor, the buzzer and ...
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2answers
52 views

Reading Digital Pins and Outputing on entire Ports

I'm very new to coding so please don't grill me. I'm working on a scientific project where I am using a NI-DAQ to digitally trigger mosfets to trigger 300us - 3ms pulses on two high powered LED ...
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1answer
40 views

1st LED turn ON when 1st button is pressed and other LEDs remaining OFF

I have 2 LEDs and 2 buttons. What I want to code is when first button pressed the 1st LED turn on (stay on for 5 seconds) and 2nd LED remain off, and same if 2nd button pressed the 2nd LED turn on and ...
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0answers
33 views

Cannot give battery through USB cable

I just make a simple circuit with uno and breadboard ,that connected 4 LED and 4 IR sensor. The arduino program is simple that makes the light on or off with the determination of IR sensors . However ...
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1answer
51 views

Problem with SPI when using rf24 NRF24L01 transceiver with LED matrix MD_MAX72xx

I am currently using Arduino Mega to use a LED matrix and a NRF24L01 transceiver. for LED matrix, I use MD_MAX72xx library. While for the transceiver I use the RF24 library. I am already able to ...
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1answer
43 views

Data type problem

I have a program I would like to ask:   I use the Bluetooth control LED to light up. In the picture, the serial port window shows r, but the LED does not light up. What went wrong? Ask everyone, thank ...