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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Autoranging ohmmeter

Note: Before i explain my issue i would like to note that I am a beginner in electronics. Please pay attention to that when providing solutions and explanations. Thank you. I have succeeded at making ...
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949 views

Arduino on breadboard, and then soldered using a board made on Eagle but won't work

So I'm looking to create an arduino clone to mount on one of my robots. I started off making the arduino on a breadboard, using the instructions found on Arduino's own website and I succeeded. It ...
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How to generate true random numbers over Arduino Uno without any external hardware?

Using a 'random' function in sketch gives same pattern of numbers every-time. But, I need to generate different numbers such that any number to repeat itself should have a very less probability.
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Trouble when avoiding delays

I am new to Arduino and I am learning how to avoid using delay. I have written some code to move my servo by 20° using delays, but can only move the servo once with my current code. In setup(), I ...
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Arduino DC motor causes disturbance. What can cause it?

I tried to fix this problem the whole weekend but, after no success I decided to post it here. I would really appreciate any help. The problem The Wi-Fi module activates the DC motor and lets it run ...
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Read RC receiver channels using Interrupt instead of PulseIn

I am designing my own quadcopter control algorithm, whereby I currently read 4 RC receiver channels using PulseIn on each loop in the following manner: ch1_raw = pulseIn(rcPin1, HIGH, 25000); In ...
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2answers
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UNO analog input voltage reading not accurate

My loop code is this: // read the input on analog pin 0: int sensorValue = analogRead(A0); // print out the value you read: Serial.println(float(sensorValue*5000.0/1023)); delay(1); // delay ...
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1answer
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PWM signaling with Arduinos: What is the reason for the ground connection?

This may sound like a very dumb question and I apologise in advance. I've gone through reading about PWM and working on some example sketches to control PC fan speeds using PWM and Arduino. In all ...
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1answer
329 views

What is causing my Uno to wake up?

NOTE: this code was working perfectly fine in another program. I have a simple piece of code that puts the Arduino to sleep. When it is finished and intergrated into my project, it will only wake the ...
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2answers
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Formula / calculation of the function random() / randomSeed()

In which file can I find the calculation that is called with random()? If it is not too much could you also post the content in your answer? I am using an Arduino Uno and its standard IDE. I found ...
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Servo won't stop rotating

I have an Arduino Uno R3 board and after some time not in use it seems to have corrupted. My code is below, basically I want to rotate a servo 90 degrees every 12 hours but as soon as I plug it in the ...
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1answer
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Expected unqualified ID before numeric constant

After debugging and having some conflicting declarations about analog pins, I finally thought it was done, after compiling I got this error: 32:0, 1: 31:12: error: expected unqualified-id before ...
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Make Sure \n is the last character in serial string

I have an Arduino that I've put between a computer and an RS485 device. The job of the Arduino now is just to transmit data but will eventually do data logging and have a small user interface as time ...
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Bit shifting fails with warning: left shift count >= width of type

Given the following minimal working example. I tested this initially with uint16_t and it worked with no warnings. After that, I adjusted everything to work with uint32_t. #include <stdint.h> /*...
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LEDs: difference between common anode and common cathode?

What is the difference in using a common anode and common cathode of the 7 Segment in interfacing with the Arduino? How can you change the code if we need to add another 7 Segment display? How can ...
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Sending a value from one arduino to another

I wonder if it is possible to send a value from one arduino to another. Basically, I have one arduino measuring let's say weight, but I want to display that value using an lcd in another arduino. ...
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8answers
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Two sensors on one input

I got this question from my teacher the other day and I can't figure it out: If you have two sensors from two different outputs but want them to go into one input, what do you need, and how can you ...
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2answers
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Connecting an Arduino to a telephone line?

I would like to connect my Arduino Uno to a telephone line in order to answer a call, record a sequence of DTMF tones, generate a DTMF tone in response, and hang up. The telephone line uses a ...
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1answer
692 views

Is my ATmega broken, and would replacing it with another break that one, too?

I was communicating between my computer and my Arduino Uno R3 through Bluetooth using this Bluetooth module. The connector I use has a red wire where it connects to GND, and a black wire where it ...
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1answer
149 views

How to save a state - make an arduino run a code only once/make aruduino bahave differently the next time he is on

Im building a arduino based bicycle speedometer. When the code starts the user picks his bike size (which I need to calculate the radius). Then I have a state finite machine where the user taps the ...
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How to connect Wi-Fi shield ESP-12E-ESP8266-UART-WIFI-Wireless-Shield with Arduino

I have bought this shield from ebay and now I don't know how to use it, ESP 12E ESP8266 UART WIFI Wireless Shield for Arduino UNO R3 Bouclier Sans filfr: There are no instructions in the box or ...
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2answers
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RTC MCP7940M not counting up

I'm able to set a time and to read it back without any problems but it doesn’t tick up. It stays the same. Even if I restart the serial monitor and thereby resets the buffer(?). So it seems to me that ...
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872 views

Cannot compile C++11 code via Makefile

I am building my Arduino project with a makefile: BOARD_TAG = uno ARDUINO_PORT = /dev/ttyACM0 USER_LIB_PATH = /home/prakhar/dev/alfred/arduino/libraries CPPFLAGS=-x c++ -std=c++11 -Wall -...
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Does ATMega 328/2560 chips support JTAG-type programmer and hardware debugger?

As stated in www.Arduino.cc FAQ, "Can I use an Arduino board without the Arduino software? Sure. It's just an AVR development board, you can use straight AVR C or C++ (with avr-gcc and avrdude or AVR ...
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350 views

Does the tone() generates unwanted signal?

I was trying to use the tone function for another project but I found that it also generates an undesired frequency (not the harmonics above of square wave it generates) but a lower frq square wave. ...
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How to measure resistance of TFT Touchscreen

I'm using a TFT Touchscreen shield with my Arduino UNO, and I'm running "tftpaint" example by Adafruit. I've noticed that when initializing the Touchscreen object, a resistance value must be provided....
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Programmatically Change Arduino Com Port Name

I have some devices that, when I plug in, will display a unique name, usually a serial number, as opposed to "COM #" is there any way I can have my Arduino Uno (or Mega) give itself a different name ...
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122 views

Is there any chance of fixing it?

I am new to arduino and robotic stuffs and I thought it would be a good idea to test circuits on my breadboard using arduino's R3 5V pin as power supply. The accident happened when I short circuited ...
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3answers
502 views

Not getting proper readings on Arduino from MAP Sensor

In recent project, I have to take reading from MAP sensor. So basically, we used analog pin for this. But in my case, I don't get proper result which actually I want. When I'm taking readings through ...
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How to clear FIFO buffer on MPU6050?

my MPU6050 works very unstable , the problem is unable clear excessed FIFO buffer on MPU6050, I am using Jeff Rowberg's MPU library and according to his DMP example but without using interruptions,...
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1answer
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ov7670 + Sd Card + arduino

I have three devices for making a motion activated security camera system: this is the camera : LINK OV 7670 this is the SD Card module: LINK and a basic motion Sensor: PIR with 3 pin I have an ...
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Why bootloader sizes differs from 0.5 to 8 kilo bytes for different boards?

According to official web info bootloader sizes are 0.5, 2 and 8 kilo bytes for UNO, Pro mini and ATMega2560. I believe all three boot loaders do similar job of receiving serial link data and write to ...
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Parsing JSON on the Arduino

I'm using the ArduinoJson library. There is a great example for parsing a single JSON object in the source code. I am attempting to iterate over an array of JSON objects: #include <JsonParser.h>...
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how does serial port communication work under the hood?

im just looking for how to send/ write date to pc over serial port from arduino..vice versa. I have few Question to ask after taking so much time and couldn't figure it out myself. I hope you guys ...
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LCD scrolling down problem

I have a list of set-ups and I only have 2 rows in the lcd , I'm trying to scroll down for the moment and I'm doing this by changing the row in the setcursor function to either 0 or 1. However since ...
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4answers
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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 ...
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1answer
808 views

cannot convert 'bool' to 'PinStatus' for argument '2' to 'void digitalWrite(pin_size_t, PinStatus) on Arduino Uno Rev 2 Wifi not working

I am a newbie to micro controllers and struggling to figure out how to fix this issue. When using an older Arduino micro controller it works fine, but when I use a new board (Arduino Uno Rev 2 Wifi) ...
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Power on reset with arduino uno can never happen. Can this be fixed?

When an Arduino Uno is powered on, the USB chip's DTR output pin may (is, in fact) low for a while. This means that the capacitor C5 is connected from the 328p reset pin to ground. Thus, when power ...
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1answer
235 views

How well will the Arduino Uno survive in a vacuum?

Im doing some experiments with Pocketlab and Arduino, Vacuum will get to around -30inHg. I tried with my raspberry pi and it just kept dying everytime a vacuum was pulled. The only problem I can image ...
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How to choose a transmit pin in the IRremote library for an Arduino Uno?

I am looking for a way to choose a pin on the Arduino Uno. This pin will be used to send the signal of an IR LED. I am using the IRremote library. e.g. Below is the IR send demo which uses pulse ...
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Why do my temperature sensor values become inconsistent when additional hardware is added to the board?

I have this strange problem. My TMP 36 sensor works fine when it is the only thing connected to my Arduino Uno board. The voltage measurements, and thus the temperature, are accurate and consistent. ...
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Do I need 3 voltage dividers to control ESP8266

I am buying an ESP8266 and the plan is to control it serially from an Arduino. I am going to use a voltage divider(Using a voltage divider is temporary and I know the cons of using voltage dividers). ...
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3answers
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Multiple GSM shields on one Arduino

I am looking for a way to listen for received text messages on multiple numbers. When I came across the Arduino and its shields, I thought to myself this might be the perfect way to do just that. One ...
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1answer
154 views

In Linux, how do I get this Arduino library to work

In Linux Fedora 20 Arduino I want to use the Timer library from here, from which I have downloaded the folder Timer-master.zip, but, when I try to import it, I get the Arduino message that it cannot ...
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Why digital pin not reading ON from push button switches connected to 5V and pull-down 10K resistor?

Here's my circuit: And the code: //pins const int control1 = 2; const int control2 = 3; const int enable = 9; const int pinDirection = 4; const int pinOnOff = 5; const int pot = A0; //states ...
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Explain what is meant by “Arduino core”

What is an "Arduino core"? Are there many different "Arduino cores"? such as a core that applies to LCD displays, another core that applies to servos, etc.?
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491 views

How to on/off light dimmer using another pin?

In recent project, I'm working with light dimmer. Let me explain with example of fan. In switch board, we have a fan switch which can able to ON/OFF our fan & FAN REGULATOR which vary speed of ...
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2answers
2k views

Sending uint16_t over I2C

How do you transmit and read a uint16_t over I2C? I'm trying to read two uint16_t values from a slave device, and I'm seeing nonsensical readings. This is the code on my slave Arduino Uno: #include ...
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4answers
465 views

Why/when to use IoT publish/subscribe protocols rather then RESTful HTTP?

I am sending data (GPS coordinates) from Arduino once a minute with HTTP POST request to REST API (in OpenShift PaaS). Data is then stored to MySQL db. Would so called "IoT" publish/subscribe ...
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1answer
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How to append float value of into a string ?

I have a float variable lng = 33.785469 and lat = 78.126548. Now can I convert them to String and append in a String variable "my_location" as "your location is \nlng = 33.785469 \nlat = 78.126548". I ...

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