Questions tagged [arduino-uno]

The Arduino Uno is the most common of the Arduino boards. It is based on the ATmega328P microcontroller.

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5answers
25k views

How to have an Arduino communicate with 3 other Arduinos?

I was wondering how I can get 4 Arduinos in total to communicate with each-other through a wired connection. The goal is to have the master Arduino send a number 0-100 to each of the other Arduinos. ...
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5answers
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Inappropriate ioctl for device

I am using an Arduino Uno and a Mac and trying to upload my code into the board. I tried uploading the program from different computers(MacBook Air and Pro) and I still have this problem. How do I fix ...
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2answers
30k views

How to send numbers to Arduino UNO via Python 3 and the module serial

I am new to Arduino (and computer programming in general), so I apologize if this question looks silly. Once I set up a basic arduino-LED connection, I have problems sending INTEGERS to arduino ...
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2answers
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Male header pins on Arduino Uno

On my board, there are 12 (2 groups of 6, each group consistent of 3 rows of 2 pins) weird male header pins. What are these, and how would you use them?
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2answers
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How to detect the direction of a rotary encoder?

I'm trying to detect the direction of rotation for an incremental rotary encoder. I'm supposed to get +1 for clockwise and -1 for counter-clockwise. However, I receive random values. Any help ...
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2answers
122 views

How to re-solder the resistor in order to reprogram the Atmega8U2

As I see here I need to reprogram the ATMEGA8u2: https://www.arduino.cc/en/Hacking/DFUProgramming8U2 I need to solder a 10k resistor into a specific place. In a previous attempt I did that and ...
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2answers
9k views

Why can't I upload a sketch while other components/devices are connected to my Uno?

I wanted to make a fairly simple circuit which would flash a series of LEDs in sequence, using my Arduino Uno (more specifically, a SainSmart clone). I wrote my sketch and it compiled fine. After that,...
5
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1answer
1k 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 ...
3
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1answer
286 views

Change Servo Speed With RedBearLabs BLE Shield

I recently got the RedBearLabs BLE shield to use it to control two high spped continuous rotation servos. I have the BLE example sketch loaded and the ios controller app works. The problem is that the ...
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2answers
6k views

Sets of Ultrasonic frequencies using arduino uno

Is it possible to create a set of ultrasonics frequencies using only the Arduino? What code to be used? And how am I going to do for it to work? For this project I need to focus in the emitter side; ...
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2answers
11k views

SIM900a Mini Modem, IMEI 0, help with TX RX pins

I have Simcom SIM900a GSM (SIM900a Mini DEV Board v3.9.2) and I am interfacing it with Arduino UNO. I have no idea how to connect SIM900a to Arduino UNO. What I did now is: I connect the following ...
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1answer
6k views

How to convert a String number Into a int value?

I want to convert a string into a int value. in my real code, I receive a string "Slider 255" the number after slider changes from 0 to 255, so I want a int value to be equal to that number. This is a ...
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2answers
5k views

Problem with sending a POST request using the WiFiEsp library [closed]

I'm using an ESP8266 version 1 with the WiFiEsp library to connect to WiFi, and that works just fine. I'm setting up the device using the same code as in the example WebClientRepeating. I need to ...
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0answers
2k views

Programming an Arduino over the air using an ESP8266

This question stems from this article (Originally in Spanish/English) which Hack a Day summarizes (Includes link to partial English translation). These articles show that it is possible to update an ...
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4answers
26k views

ESP8266 + Arduino Uno: Can't send AT Commands

I'm trying to get the ESP8266 up and running without a FTDI chip, just my Arduino Uno. But it seems really difficult. What I did: attach the ESPs VCC directly to Arduino Uno 3.3V; RX->TX; TX->RX ...
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1answer
2k views

Webserver on Arduino: Refresh issues

I am using W5100 Ethernet Shield Network Module with arduino Uno as a webserver to trigger four relays connected to it. The relays may be toggled through the four buttons attached to it physically, ...
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1answer
1k views

Storing latitude and longitude floats as chars with specified precision

I am receiving lat and long data from a GPS and want to store these numbers in the middle of a sequence of chars. E.g. lat = -23.123456 long = 135.123456 I am after something like "Your coordinates ...
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1answer
218 views

4WD rover not moving

I am trying to make a 4WD vehicle. I have uploaded the code, all connections are OK and I have used L298N and HC-05. But when running the Bluetooth app, the motors do not rotate. I tried with both an ...
0
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1answer
237 views

Unable to tell if error is from receiving or transmitting end

so I am having trouble sending data using software serial's write function. TX Code: #include <SoftwareSerial.h> SoftwareSerial TX(2,3); void setup() { // put your setup code here, to ...
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1answer
2k views

Why does my Arduino seem to reboot every time that I open Serial Monitor? [duplicate]

Every time that I open the Serial Monitor, my Arduino Uno, seems to go back to void setup(). Is it a normal thing?
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2answers
1k views

Why is my SRAM so quickly filled? There are not more than 60 bytes

I have just gone through all my code. At max I use 60 bytes. I have done everything in order to minimize its usage - I even store booleans as bits, not bytes! What could be happening here? The only ...
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4answers
9k views

Timer2 does not work as it should

I am currently playing with Arduino timers (on UNO currently) and I am building a library that has a function that must be called every millisecond. There is plenty of code samples on Internet so I ...
4
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3answers
4k views

Arduino shield stacking

I have an Arduino GSM Shield mounted on an Arduino Uno. Can I stack this GPS shield above Arduino GSM shield? Will there be any pin configuration problem? In GSM Shield hardware pin’s configuraton ...
4
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2answers
4k views

How to increment and decrement an output voltage by using two buttons?

I'm trying to create a code using an Arduino Uno board to increment and decrement the output voltage of the Arduino Uno which is 5 volts and I need to step it up to 10 volts which I have done below. ...
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3answers
5k views

The exact time for functions or CPU cycles for any function

I'm trying to read input data from the parallel port of a PC and send it to another device. For this purpose the input data is saved, when it's available and is sent if a flag is set. The whole ...
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2answers
5k views

Arduino Power - DC adapter

I have a 12V 2.5 ampere Dc adapter.Can i use it to power arduino uno board? It says on the arduino website that i can use 9-12V and upto 1 ampere. I am concerned with current limit here..
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3answers
10k views

Access denied when Uploading

I went to upload my sketch to my Uno (r3), but unusually, the Upload Console returned this error: avrdude: ser_open(): can't open device "\\.\COM4": Access is denied. Just started seeing this, ...
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2answers
878 views

Interface with mux-controlled LED rope

I'm working on using a GUI in Processing to control some LED rope from Adafruit, and using this multiplexer. I've gotten the following Arduino code working the way I want to cycle through the various ...
2
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3answers
1k views

Motor shield leaves no pins accessible

I just bought a motor shield for my UNO, in the pic below: Plugging it into the uno leaves no pins accessible on the board. I’d like to use it to build a robot car, but there’s nowhere to plug in the ...
2
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3answers
11k views

Integrating an analog signal using Arduino Uno SMD

I need to integrate an analog signal using my Arduino Uno. I am sampling the input signal at 1 KHz using a delay command in my void loop() and adding up the values at the analog read at that ...
2
votes
1answer
91 views

Why doesn't pin 3 blink? It blinks in another program

I used toneMelody example code (sketch sample 02.Digital->toneMelody) on an Arduino UNO. Then I wanted to blink an LED with the melody. Here's the code: #include "pitches.h" #define BLUE 3 // pin 3 ...
2
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1answer
197 views

Arduino Standalone - photo shows incorrect pin wired to MOSI

I have been building a standalone Arduino on a breadboard following the guide, Building an Arduino on a Breadboard. The guide is generally very good, however, I have yet to get the Arduino working, ...
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3answers
994 views

Why connect arduino with Rasberry pi?

I have a question about connecting a Arduino with Raspberry Pi. What is the benefit of connecting the two?
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1answer
193 views

Usbasp Arduino Uno Bootloader Flash Error - Win 10

I'm trying to flash an Arduino Uno using usbasp but i'm getting the following error,I have checked all the connection and voltage using multimeter but still this error: Arduino: 1.8.8 (Windows 10), ...
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3answers
4k views

Programatic FOTA (Firmware-Over-The-Air) upgrades with Uno R3

I have been searching for a way to upgrade the sketch on my Arduino Uno wirelessly (preferable WiFi, but not a must). Does the Uno support such function? If not - are there any other boards that might ...
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2answers
714 views

Uniform timing when using Arduino for data acquisition

I am using Arduino UNO together with a SPI ADC (LTC1859) and SRAM (23CL1024) to record a series of data points at approx 2 kHz sampling rate (let's say a few thousand data points). I have some ...
1
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1answer
1k views

SoftwareSerial error

I have arduino , upon arduino I have Arduino GSM shield (Tx-2, Rx-3, Modem reset-7) and upon it, I have the Adafruit GPS Logger shield. I am trying to send sms of Latitude from the GPS Logger shield ...
1
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1answer
3k views

Adding data to an SD card file

I'm reading data from the Shinyei PPD42 particle sensor unit. Everything seems to work, but I'm encountering two problems When I restart Arduino, the file is not being extended, nor overwritten. It ...
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1answer
2k views

DHCP Failing on Arduino Uno [closed]

I have an Arduino Uno with and Ethernet shield. There was a project which had it connecting to the network. It no longer does. Through debugging, it seems that Ethernet.begin(mac) == 0 never returns, ...
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1answer
1k views

Analog inputs showing value even there is nothing connected to it [duplicate]

After watching something weird on the serial monitor I wrote a simple code to monitor the analog pin input values. There was nothing connected to the analog pins still they where showing decimal ...
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1answer
1k views

Webserver on Arduino: How to 307 temporary redirect

I originally asked this question. Regarding a webserver Refresh issue on arduino. I am totally new to web development and ethernet. The answer from @Majenko is correct, but I do not understand how ...
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2answers
4k views

What is the proper way to turn an Arduino UNO into an ISP?

I have a bricked Arduino Uno and I want to try to flash the bootloader. I'm trying to figure out how to do it. On this tutorial from SparkFun you can see this diagram: They also show this table of ...
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1answer
620 views

How to add Ultrasonic Sensor to the board?

I am making an RC car , have combined the Arduino UNO R3 with the AR 293d, and pluged in the HC-SR04 sensor to the SRO4 hole at the left top corner in the below graph. However, besides one sensor I ...
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1answer
878 views

Demultiplexing Arduino with C++ code

I have been working on a small project recently. I have a circuit like in the image below: Hardware Setup Demultiplexer IR Test As you can see I have 8 IR LEDs, which are driven by an MC14051B ...
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2answers
3k views

how can i generate square pulse at 50khz frequency to drive two mosfets at a duty ratio .6 [closed]

I have to switch 2 MOSFET IRF640 at a duty ratio of .6 and the frequency of switching is 50khz how can I generate it with a single aurdino
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0answers
942 views

Analog Input not going to Zero

Arduino Uno user here I am building a project with 4 analog inputs A0 dose not work. A1 A2 and A3 work perfectly fine! But for last input when I connect to A4 or A5, then they do not go to zero. They ...
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1answer
168 views

Accessing Values From Array Within a Library

There are many great examples of how to access information from an array on the net. I ran into a specific case that has me confused. I am using a library for attiny 85 TinyPpmReader.h. This is a ...
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3answers
62 views

RGB and Potentiometer

How do I start this program??? int x=0; int P1=A5; int P2=A4; int P3=A3; int R1=3; int G1=5; int B1=6; int R2=9; int G2=10; int B2=11; int sValue1; int sValue2; int sValue3; int oValue1; int oValue2; ...
0
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2answers
280 views

How to interface ESP8266-01 Wifi Module with Arduino Uno

I have an Arduino Uno and ESP8266-01 Wifi module with me currently. So I'm going to use ESP8266 to connect to the MQTT broker to allow me publish data to other devices. However, I have a problem with ...
0
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1answer
41 views

How to connect accelerometer, GPS, microphone and a GSM module to a Arduino? [closed]

I am a noob in the Arduino world and have only started reading about it. I have zero experience with Arduino some suggestions to increase my level will also be highly appreciated. But I have a lot of ...

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