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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votes
1answer
268 views

I can't seem to receive data to the ArduinoStudio serial monitor on ubuntu 14.04 [closed]

I'm using the Arduino Starter Kit so I have a Uno R3 and going through the examples I'm trying to read temperature data from my controller in Arduino Studio. In essence my problem can be reduced down ...
10
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1answer
15k views

How do interrupts work on the Arduino Uno and similar boards?

Please explain how interrupts work on the Arduino Uno and related boards using the ATmega328P processor. Boards such as the: Uno Mini Nano Pro Mini Lilypad In particular please discuss: What to use ...
10
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4answers
23k views

Why is my real time clock getting the wrong time from my PC?

I want my real-time clock to set its time as the time on my PC. However, when I run the following sketch, the real-time clock reports the time as being 32-33 seconds earlier than my PC says the time ...
10
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2answers
23k views

Difference between /dev/ttyACM0 and /dev/ttyS0 (Arduino IDE ports under Linux)

I use the Arduino IDE to upload sketches to my Arduino Uno. My OS is Linux Ubuntu 14.04 LTS. The Arduino IDE has two ports by default for communication with the Arduino Uno: /dev/ttyACM0 /dev/ttyS0 ...
10
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2answers
721 views

Arduino Uno R2 and Ethernet Shield R3 compatibility

I bought an Ethernet Shield R3 for my Arduino Uno R2, but since R3 has extra pins it does not fit. Can I use the shield? Should I cut off the extra pins. What do I need to do to make it work?
10
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1answer
13k views

Both red and blue led of ESP8266 stays on

I've connected ESP8266 to Arduino UNO. After a getting a huge trouble I successfully managed to run some AT commands. I have also tested AP mode. Then I got some trouble with software serial ...
10
votes
1answer
2k views

Update Dynamically Tkinter Widget Scale from Arduino Ports using python and firmata

I'm having trouble trying to get Arduino digital ports values and set these values into a Python Tkinter Widget Scale. I'm using Python and Arduino with Firmata. I'm able to access my arduino board ...
9
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6answers
31k views

Very long delay() possible?

I'm trying to make an opening and closing little door that should open or close every 12 hours. I was wondering if I could just make a small looping script with a delay() for 12 hours, delay(43 200 ...
9
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2answers
26k views

Increase PWM bit resolution

I would like to increase the PWM bit resolution of the Arduino Uno. At this moment it is 8-bit which I consider too low. Is this possible without losing the ability of interrupts and delays? Koen ...
9
votes
3answers
73k views

Why is my LCD 16*2 is not displaying any characters, although all the wiring is correct?

Recently I have linked up a typical 16*2 LCD (Liquid Crystal Display) display to my Arduino Uno and have linked all the pins up. Here is my connection:(LCD pin first) 1=GND, 2=+5v, 4=11, 6=12, 11=5, ...
9
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1answer
2k views

Why connect a diode between the reset pin of Arduino and 555 timer?

I am trying to create a watchdog timer using 555 IC and I am following this. I do not understand why a 1N4148 diode is connected between the reset pin of Arduino and the output of the 555 timer. As ...
9
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4answers
41k views

How do functions outside of void loop work?

I am used to Arduino sketches with a void setup() part that runs once, and a void loop() part that keeps looping. What happens when you have void functions outside of the main void loop()? Will these ...
9
votes
5answers
11k views

How can an Arduino output a specific (i.e. 56 kHz) carrier frequency?

I'm working on a free space optics project to send data wirelessly between two points. To accomplish this I'm using an IR LED connected to an Arduino Uno that pulses with a 56 kHz carrier ...
9
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2answers
4k views

Does the Arduino Uno have two crystals?

Take a look at this picture: I think most of use agree that the "big silvery" thing on the board (red) is the famous 16 MHz crystal of the Arduino. That's what I've believed until very recently. ...
9
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3answers
12k views

How to call C functions from Arduino sketch?

I would like to know if there is a way to call functions that are contained within C files using an Arduino sketch? My C file declares and defines a function. To save putting the messy function ...
9
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3answers
24k views

Arduino time keeping using millis() is not accurate or correct?

I have been using the Arduino to record some data. In my Arduino sketch I also used the millis() function so I can keep track of the time at which each value I am measuring is taken. However, I ...
9
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2answers
43k views

How do I convert a float into char*?

Asked this question on Electrical Engineering Stack Exchange and was directed here: Pretty self explanatory; how would I go about converting a float into a char*? I have code in which the float '...
9
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3answers
4k views

Sending colours to vga monitor

I'm looking for a simple way to send a signal from my arduino to a vga monitor. What would be the easiest method, and what components would be needed? I don't need to display an image, just a ...
9
votes
1answer
24k views

ICSP pin, what is it actually?

What is an ICSP pin. I have read that it is a AVR and a tiny programming header for the Arduino, but what is an AVR and what does an ICSP pin do?
9
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2answers
2k views

Can the 2nd MCU on the UNO R3 be used for keyboard emulation?

Following on from What's the 2nd ICSP header for in Arduino Uno R3? I was wondering how this could be hacked to our advantage. For example, could that firmware be rewritten to have the UNO ...
9
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3answers
2k views

Digital Read Serial tutorial - calculating the resistor value

The Arduino Digital Read Serial tutorial guides you through the wiring of a simple button. My questions are centered around the resistor. Why is the resistor necessary? I think I understand this, ...
9
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3answers
23k views

nRF24L01 pipe question

I am looking through the example code found here. I know there are 6 pipes that the nRF24L01 module can use but I've been searching the internet for the address designations and have been able to find ...
9
votes
1answer
3k views

How can a 5v Uno talk to a 3.3v Due?

I currently have an Uno (which operates at 5v), and I'm looking at buying a Due (which only operates at 3.3v). I'd like to make them communicate via Serial or SPI or similar, but presumably connecting ...
9
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3answers
81k views

Use all pins As digital I/O

Increase the number of digital pins There are many post that explain how to use more than just the standard pins on the various arduinos but none of them explain the limitations and the proplems ...
9
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2answers
27k 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 ...
9
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2answers
1k views

RFID/NFC (13.56 MHz), is it possible to send raw bytes and receive response?

I'm trying to implement a card reader (i.e. credit cards) for shopping purposes, and AFAIK those cards are ISO 14443-A compliant (Mifare Classic 1K). I already made an Android app that can send custom ...
8
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9answers
9k views

Different ways (and the fastest) to compute sines (and cosines) in Arduino

I am using an Arduino Uno board to compute the angles of my system (robotic arm). The angles are actually 10 bit values (0 to 1023) from the ADC, using the full range of the ADC. I am only going to be ...
8
votes
2answers
4k views

Arduino interruption (on pin change)

I use the interrupt function to fill an array with values received from digitalRead(). void setup() { Serial.begin(115200); attachInterrupt(0, test_func, CHANGE); } void ...
8
votes
5answers
14k views

Reasons why it is not OK to connect a relay directly from an Arduino digital pin

After looking into various schematics on controlling a relay via an Arduino, I have noticed that, most of the time, transistors are used to switch the separate supply into the relay coil rather than ...
8
votes
4answers
3k views

How to move from arduino to physical prototype

I've been reading a bit about moving from Arduino to PCB and it seems a bit daunting. For now, all I really want to do is take something I've built, and make a few changes so that I can actually ...
8
votes
6answers
94k views

Send AT commands to ESP8266 from Arduino Uno via a SoftwareSerial port

GOAL From Arduino UNO, send AT commands to ESP8266 via a SoftwareSerial port and receive results. CURRENT STATUS I either send AT commands and get nothing back (wiring scheme 1) or I send AT ...
8
votes
3answers
5k views

Is it possible to program an Arduino Pro Mini using an Arduino Uno R3?

I've recently received an Arduino Pro Mini as a gift, and I don't have an external USB programmer to program the Pro Mini. However, I do own an Arduino Uno R3, and I think it would be possible because ...
8
votes
1answer
770 views

Can I program a 3.3v chip on a 5v board?

I bought a Gertboard a while ago, and one of the features it has on-board is an ATMega328 (DIP). However, since the Gertboard is designed for use with the Raspberry Pi, it only operates at 3.3v, so ...
8
votes
1answer
5k views

What are the SVG pins for on the SainSmart Uno clone?

I bought a SainSmart clone board which is compatible with the Arduino Uno R3. Alongside each of the standard IO pins, there is a row of 3 additional pins (male). They are arranged in columns, marked S,...
8
votes
2answers
9k views

Basic makefile for avr-gcc

I would like to make a makefile for compiling c programs for the arduino. I am somewhat familiar with make but have never used it with avr-gcc. What is the simplest way I could put the commands below ...
8
votes
4answers
32k views

What is the work of pulseIn?

I have code for an ultrasonic sensor which I found from a site. Here is the code: #define trigPin 12 #define echoPin 13 void setup() { Serial.begin (9600); pinMode(trigPin, OUTPUT); pinMode(...
8
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2answers
5k views

How to pause Arduino for 1 millisecond through MATLAB?

I have been able to connect MATLAB to my Uno with this line of code: a = arduino('COM4'); through this package: Matlab support package for Arduino. Right now, MATLAB is my main script that will ...
8
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2answers
1k views

Performance of internal vs external resistors

Is there any significant performance trade-off between buttons wired with the internal vs external pull-up/down resistors? I see a lot of tutorials demonstrating the use of external resistors when ...
8
votes
2answers
813 views

Arduino ADC Reference Voltage if it is Battery Powered

I am looking to possibly monitor battery power to the Arduino using its ADC. This is fairly straight forward and simple (especially if using the Arduino API); however, if the battery is powering the ...
8
votes
1answer
2k views

How can the Arduino Uno support up to 12 servos if it only has 6 digital PWM pins?

According to this: The Servo library supports up to 12 motors on most Arduino boards and 48 on the Arduino Mega. On boards other than the Mega, use of the library disables analogWrite() (PWM) ...
8
votes
2answers
2k views

Burning sketch with I2C

Not a pure Arduino question really. I'm actually using a standalone ATmega168. So far I've been using AVR-ISP programmer (working from AVR Studio) to program the chip. After everything is done, the ...
8
votes
1answer
281 views

Will the arduino power autoselection logic short the regulated 5V and the USB 5V?

From the reference design of the Arduino UNO r3, I find that USBVCC will be connected to +5V via mosfet T1 if Vin is below 6.6V. Doesn't this short the two sources if Vin is just below 6.6V? The ...
7
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5answers
2k views

When Raspberry Pi is preferred over Arduino

We are doing some projects in class. One of my friends is doing a weather and humidity station using raspberry Pi with a couple of sensors and LCD. I have a little experience in Arduino. So I asked ...
7
votes
3answers
925 views

Using Arduino for Industrial process

I was wondering if the Arduino is applicable for Industrial monitoring, I want to make a real time status of the presses in our company. I haven't seen or read much about people using Arduino at an ...
7
votes
5answers
31k views

How to expand program memory on an arduino?

Sometimes I run out of space of the program size for the embedded C program that I want to put on an arduino. So what chip do I need to expand the program memory of the arduino so that I can use ...
7
votes
5answers
290 views

Extremely cheap “Arduino” for single tasks?

I have been thinking of a million things to do with my Arduino, but those things are extremely simple and it would leave my Arduino as a $25 waste. For example, programming Arduino to control my ...
7
votes
3answers
1k views

How to increase life of EEPROM?

I want to store a few (8 as of now) IR codes into my Board's EEPROM. It would be great if someone could suggest a few tips to maximize the lifetime. The IR codes in my sketch are saved in array of ...
7
votes
2answers
3k views

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?
7
votes
6answers
12k views

Is it possible to press a button from Arduino and my computer will get a key event?

My idea seems easy: I connect a button with arduino, then write some code and upload it to arduino. Then I open the notepad(or any other editor) on my computer. When I press the button, there will ...
7
votes
2answers
1k views

Convert a Bitstring into an integer value

I have got a String filled up with 0 and 1 and would like to get an Integer out of it: String bitString = ""; int Number; int tmp; bitString = ""; for (i=1;i<=10;i++) { tmp= analogRead (...