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Questions tagged [arduino-uno]

The Arduino Uno is a microcontroller board based on the ATmega328 and created by Massimo Banzi.

The Arduino Uno is a microcontroller board based on the ATmega328 and created by Massimo Banzi. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a USB-to-serial converter.

Revision 2 of the Uno board has a resistor pulling the 8U2 HWB line to ground, making it easier to put into DFU mode.

Revision 3 of the board has the following new features:

  • 1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible with both the board that uses the AVR, which operates with 5V and with the Arduino Due that operates with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
  • Stronger RESET circuit.
  • Atmega 16U2 replace the 8U2.

"Uno" means one in Italian and is named to mark the upcoming release of Arduino 1.0. The Uno and version 1.0 will be the reference versions of Arduino, moving forward. The Uno is the latest in a series of USB Arduino boards, and the reference model for the Arduino platform; for a comparison with previous versions, see the index of Arduino boards.

Quick summary

Microcontroller               ATmega328
Operating Voltage             5V
Input Voltage (recommended)   7-12V
Input Voltage (limits)        6-20V
Digital I/O Pins             14 (of which 6 provide PWM output)
Analog Input Pins             6
DC Current per I/O Pin       40 mA
DC Current for 3.3V Pin      50 mA
Flash Memory                 32 KB (ATmega328) of which 0.5 KB used by bootloader
SRAM                          2 KB (ATmega328)
EEPROM                        1 KB (ATmega328)
Clock Speed                  16 MHz

Detailed specifications: http://arduino.cc/en/Main/arduinoBoardUno#.Uyqh84X-tqc

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What is the constant ARDUINO for? it used to be 22 but is now 100

I am using thermocouples and downloaded the MAX6675 library. I wondered what the value of the ARDUINO constant in the following lines is for. #if ARDUINO >= 100 lcd.write((byte)0); #else lcd.print(0, BYTE); #endif lcd.print("C "); …
Eugene
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Arduino UNO, C3300 + PHP Webservice challenge

I'm working on an Arduino UNO project with a CC3000 WiFi shield. I've come to the point where I, without a problem can post to a locally hosted webserver (tested with MAMP), but I can't seem to find the right way to post to a remote server - I've…
Thomas
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where is the Serial.println() defined ..? can i see source code for it?

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 can guid me please. First, i found i can use…
denis_choe
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Stepper Motor not rotating properly/precisely

I would like to control a tray to move back and forth automatically between several positions automatically. Hardware: arduino nano / mega, TMC2209 and TB6600 stepper motor drivers, stepper motor 23HS84830. Power Supply: 12V/5A Problem: I wrote the…
LDS
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serial.serialutil.SerialException: could not open port 'COM3': FileNotFoundError(2, 'The system cannot find the file specified.', None, 2)

i'm making a web server that can contro an arduino with python and i get this error: serial.serialutil.SerialException: could not open port 'COM3': FileNotFoundError(2, 'The system cannot find the file specified.', None, 2) from flask import…
MMCH
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Arduino POST request to Laravel API

Hi couple of days I'am trying to start working simple project with Arduino Uno Wifi rev2. The scope is to read rfid data from card or chip, send rfid code to webserver and read response from it. Response will contain name of user which is assigned…
Johny
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How to control the Led's in a 5*5 Led - Matrix with the help of 5*5 push-button

I want two Led's ( Led 1 and Led 3 ) in a 5*5 Led - Matrix to light up and when the corresponding buttons in the 5*5 push-button are pressed the Led's turns off and another two Led's ( Led 3 and Led 5 ) should light up and when the corresponding…
Paulson Raja L
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Is there a way to use Arduino CLI to compile sketch.ino to a .bin file?

I want to upload a sketch on my Wemos D1 mini, via OTA using Arduino CLI or any other solution, but not using Arudino IDE, because i need to make the process self running. (1. get the code from web / 2. save it to a sketch.ino file / 3. compile it…
Nyikita Ciprian
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Is there any way to have an Arduino Server send an existing .html file to the Arduino client?

I am building a Single Page Application for Arduino. It graphically displays analog pin values on a wifi connected tablet. I have built the sketch but want to clean it up. I have been able to upload a sketch to my (Uno Wifi Rev 2) Arduino,…
Alan
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RC522 with ESP8266 not working Arduino uno

I have written below code for Arduino Uno to scan an RFID card using a RC522 module and an ESP8266 module to connect to my router. Now when I scan any card it should read the card number and send a request to my server's IP address and get the…
user3997016
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Serial communication between RPi and Arduino using C++

I've written two pieces of code, to create a serial communication between Arduino and a Raspberry Pi using C++. The codes are: void setup() { Serial.begin(9600); // opens serial port, sets data rate to 9600 baud } void loop() { …
MadHer
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Why does my Arduino serial port gives me semi-random numbers?

I have a basic problem with my Arduino Uno. My example code gets a number over Serial port and should print it back. int incomingByte = 0; void setup() { Serial.begin(9600); Serial.println("Hello World"); } void loop() { if…
Kim
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Sending multiple values through serial port

I am using an Arduino UNO for a project, however I don't know how to go about achieving what I want. I'm also a beginner therefore I sometimes don't know how to use some functions to do what I want. I basically want to send 3 values through the…
Lisa
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Arduino temperature sensor counting back

I am trying to get my new velleman vma320 to work with my arduino. It doensn't work at all, the temperature goes down its heated up. I've tried everything. Can somebody help me? Here is my code... int SensorPin = A0; void setup() { …
Jens Van den Eede
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12 MHz crystal speed

So I just noticed that my Chinese Arduino Uno has a 12 MHz crystal instead of the original 16Mhz. I made calculations and that turned out to be a quarter millisecond's difference. My questions: Does this affect servos or tone(), or any other…
Wadaane
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