Questions tagged [arduino-uno]
The Arduino Uno is the most common of the Arduino boards. It is based on the ATmega328P microcontroller.
8,121
questions
105
votes
3
answers
114k
views
Have I bricked my Arduino Uno? Problems with uploading to board
I can't upload sketches to my Arduino Uno.
Have I "bricked" it?
What steps can I take to work out what is wrong?
What can I do to fix it?
- 38.5k
82
votes
9
answers
188k
views
How can I create multiple running threads?
Is there a way I can have multiple parts of the program running together without doing multiple things in the same code block?
One thread waiting for an external device while also blinking a LED in ...
- 943
67
votes
2
answers
227k
views
How do you use SPI on an Arduino?
With reference to the Arduino Uno, Mega2560, Leonardo and similar boards:
How does SPI work?
How fast is SPI?
How do I connect between a master and a slave?
How do I make an SPI slave?
Please note: ...
- 38.5k
65
votes
13
answers
83k
views
Is there a way to have more than 14 Output pins on arduino?
Is it possible to have more than 14 output pins on the Arduino, I am working on a project in which I need to light up several LEDs individually. I only have an Arduino Uno, and I don't want to get a ...
- 1,903
54
votes
2
answers
69k
views
What happens if I power the Arduino with both the USB and external power voltage simultaneously?
I am a new Arduino user. I am not sure whether I can connect both USB and external supply through power adaptor to Arduino simultaneously. Would this burn the controller?
Basically, I want to ...
- 563
49
votes
11
answers
14k
views
Is an Arduino capable of running 24/7?
I'm making a simple Arduino web server and I want to keep it turned on all the time. So it must endure to stay working continuously.
I'm using an Arduino Uno with a Ethernet Shield.
It's powered ...
- 802
47
votes
11
answers
151k
views
Mac OSX Yosemite no serial ports showing for Uno R3
I have a MacBook Pro running OS X Yosemite (10.10.3). I connected my Arduino UNO R3 to my computer for the first time after the Yosemite upgrade - it worked fine before this!
When I opened the ...
- 571
35
votes
12
answers
165k
views
How can I connect to an Arduino using WiFi?
I'm working on building a solar powered, Arduino based weather station. The weather station consists of a temperature sensor and a photoresistor, and I plan to add an anemometer in the future. I would ...
- 978
34
votes
2
answers
71k
views
What are the AREF, IOREF, and the unlabeled pin next to IOREF on the Uno R3?
There are some pins on the Arduino which I haven't been able to find out anything about:
IOREF
AREF
An unlabeled one next to IOREF
What are they?
- 443
33
votes
14
answers
58k
views
Most compact method of powering Arduino from wall socket
There are a lot of methods to power an Arduino from a large range of voltages:
USB cable from PC or from a phone charger or an USB hub
step down converters
step up converters
switching power supply
...
- 729
30
votes
2
answers
67k
views
Arduino as USB HID
Is it possible to build a HID device (like a keyboard) using an Arduino uno?
At the time being, I have button inputs on the Arduino giving outputs on the serial line. So, how can I transform my ...
- 435
29
votes
3
answers
128k
views
What is Serial.begin(9600)?
I know that this is to initialize something:
Serial.begin(9600);
But I want to know what it really means?
- 541
29
votes
8
answers
38k
views
How can I get a unique ID for all my Arduino boards?
Once you have uploaded a sketch to one of your Arduino boards, it is hard to know exactly what source code led to that sketch.
Indeed, you may change the source code of your sketch on your PC without ...
- 9,142
27
votes
2
answers
10k
views
Arduino USB Power vs External Power Supply
Why is the Arduino able to accept ~5V from the USB, but requires a min of 7V when using an external power supply?
- 1,409
23
votes
2
answers
10k
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,...
- 11k
22
votes
2
answers
28k
views
Why do some pins have a different PWM frequency?
According to the Arduino reference for analogWrite(), the PWM frequency on most pins is ~490 Hz. However, it's ~980 Hz for pins 5 and 6 on the Uno, and for pins 3 and 11 on the Leonardo.
Why are ...
- 11k
22
votes
2
answers
36k
views
Is there a limit on how much current a pin can sink?
I've been experimenting with an 8x8 LED matrix controlled by an Arduino Uno. As I think is typical, the matrix uses a common anode for each row, and a common cathode for each column.
At the moment, ...
- 11k
22
votes
2
answers
75k
views
Reset an Arduino Uno in code
Is it possible to reset an Arduino (i.e., to reboot it) from code (i.e from the sketch itself)? I know that is possible with a special circuit but is there a chance to make it just with code?
Below ...
- 551
22
votes
3
answers
187k
views
How to check my Arduino board is working or dead?
When you have a board in your hand but you don't know is it working or not, how to verify if it's working or dead?
- 1,407
21
votes
2
answers
53k
views
How many interrupt pins can an Uno handle?
I am looking at using a 7 channel RC receiver with the Arduino Uno R3. In the documentation, there are mentions of a maximum of 2 interrupt pins, whereas on certain other blogs I have seen mentions of ...
- 3,847
20
votes
3
answers
25k
views
Arduino program only works when run as root
Uploading simple sketches seems to work when I run the Arduino program as root (sudo). I would like to run it as a regular user. Has anyone faced the same problem before and fixed it?
Here is what I ...
- 301
20
votes
4
answers
24k
views
Parse JSON with arduino to turn on LED
Hi i'm trying to parse JSON resposne from webserver in my arduino in order to turn on and off a LED light. I'm using the wifi client repeating example to make a get request to my server:
http://...
- 397
20
votes
2
answers
4k
views
Does Arduino Uno R3 require cooling in a closure?
I was looking at getting an enclosure to house my Arduino Uno R3, but I'm not sure if I should also attach a fan. Does anyone have experience with this? It doesn't look like much heat is being ...
- 311
19
votes
6
answers
22k
views
Smaller and cheaper alternative to Arduino Uno for permanent projects
I have played a bit around with a Arduino Uno that came in a kit with a breadboard and components. Soon I would like to make some more permanent things.
I would prefer a smaller and cheaper unit than ...
- 293
19
votes
1
answer
12k
views
What's the 2nd ICSP header for in Arduino Uno R3?
Looking at my Arduino Uno R3 board and its reference design schematic I noticed that there's a second ICSP 6-pin header. In the schematic, the connector I'm referring to is named ICSP1.
What's that ...
- 3,380
18
votes
2
answers
27k
views
What happens when I call exit() from my program?
In either of setup or loop, if I were to add an exit(0) call, where would control be passed to? What would the next state of the microcontroller be? Would it stop execution and power down?
I am using ...
- 3,847
18
votes
2
answers
6k
views
Should all unused analog input ports be tied to ground for accurate A2D measurements?
I am using the A0 port on my Arduino Uno to read the voltage output from an LM35 temperature sensor. I observed that the reading fluctuates a lot if I leave the remaining analog input ports A1 to A5 ...
anon
18
votes
4
answers
30k
views
How to get weight data from glass electronic bathroom scale sensors?
I am doing a small project with a bathroom scale but I run into some problems. I am using an Arduino Uno V3, HX711 module amp and a scale.
Scale:
HX711 amplifier:
I disassembled the scale to get ...
- 193
17
votes
7
answers
133k
views
How do I know the sampling frequency?
I am beginning to get a bit confused about sampling rates and baudrates etc. I have this Arduino code:
#include <eHealth.h>
extern volatile unsigned long timer0_overflow_count;
float fanalog0;...
- 543
17
votes
1
answer
27k
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 ...
- 38.5k
17
votes
6
answers
189k
views
How do I resolve "avrdude: stk500_recv(): programmer is not responding"?
Whenever I try to program my Arduino UNO Rev.3, I'm seeing the following error
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
...
- 455
17
votes
1
answer
102k
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 '...
- 173
16
votes
2
answers
10k
views
How many times can I upload a program or sketch to my Arduino Uno Clone Board?
I'm about to work on my very first project using arduino (I'm just about to buy one next week), and one of our professor says that we can only upload a program or sketch in an Arduino Uno Board for ...
- 161
16
votes
4
answers
14k
views
Is my Arduino dead or is it just its processor?
I have a problem with my Arduino. I can't upload any sketches to it (it gives me the error avrdude: verification error; content mismatch), but the LEDs are still blinking. Do you think that the whole ...
- 335
15
votes
6
answers
71k
views
How do I erase the memory of the Arduino Uno?
I'm just a tinkerer learning Arduino with my son and I was surprised that when I plugged the USB cord back in to the Arduino the program was still running and I thought to myself, "it's a good thing I ...
- 311
15
votes
1
answer
59k
views
What is an ICSP pin?
What is an ICSP pin? I have read that it is an AVR and a tiny programming header for the Arduino, but what is an AVR and what does an ICSP pin do?
- 353
15
votes
1
answer
5k
views
What happens when code is uploaded using the bootloader?
When I upload a new sketch to my Arduino Uno using the Optiboot bootloader, what really happens?
What is sent to the Arduino?
How does it respond?
What does "not in sync mean"?
What is "in sync" ...
- 38.5k
15
votes
3
answers
100k
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 ...
- 431
15
votes
2
answers
14k
views
What is the difference between the revisions of the Arduino Uno board?
There are three different revisions of the Arduino Uno. What changed in each revision?
- 729
15
votes
2
answers
24k
views
Controlling Floppy Disk Drive with Arduino
I am having problems controlling a 3.5" Floppy Disk Drive with an Arduino Uno.
I have the floppy disk drive powered with a computer power supply that is switched on, and the Arduino powered by my ...
- 153
15
votes
3
answers
20k
views
Can tx and rx pins on the uno be used like regular digital pins?
The uno has digital pins marked 0-13.
0 is marked as rx and 1 is marked as tx.
Can these two pins be used as regular digital pins if i am short of digital pins?
- 349
15
votes
2
answers
37k
views
What are the fundemental differences of different Bluetooth modules for beginners?
I'm a beginner to microcontrollers and electronics, albeit not really to computers and programming.
Starting out with the Arduino, I came to a point whereby I'm really interested in getting my ...
- 435
15
votes
2
answers
53k
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
...
- 281
14
votes
4
answers
39k
views
What's the deal with Uno's pin 13 LED?
(I have a Sparkfun RedBoard, but this question seems to apply to R3 Unos and Uno-compatible boards.) As I was building the first circuit in my SIK guidebook (add a resistor, LED, hook it up and make ...
- 313
14
votes
4
answers
2k
views
Some Arduino components seem ridiculously cheap
My project is an Arduino-based device, packed into a box.
It will need to use Speed, Latitude, Longitude and Altitude data to log hills it detects on to an SD. On the press of a button, it will need ...
- 273
14
votes
5
answers
5k
views
How to connect two Arduino without shields?
I'm planning an Arduino system that consists of several Arduino boards. The maximum distance between the boards is about 50 meters. I want to send basic data between these, like short strings or ...
- 2,919
14
votes
2
answers
842
views
Installing a different firmware on Arduino
Is it possible to upgrade the firmware on an Arduino so that it can do more things such as change undervolting/ overvolting in order to provide more processing power. To do this you would have to most ...
- 1,903
14
votes
2
answers
763
views
How do I figure out if my board is approaching end of life?
I have a uno that I have been using for 3 years now. I will be using it again in a rather critical project in which failure on the part of the board could be rather expensive and dangerous. So, I ...
- 3,847
13
votes
5
answers
20k
views
Reducing lag between the arduino and a processing sketch on my computer
I'm currently on project #14 of the Arduino project book.
I'm trying to control a processing sketch on my laptop using my Arduino. This is accomplished by using a potentiometer to control the ...
- 393
13
votes
6
answers
34k
views
How to output a true analog voltage at output pin
Regarding my program, it is a program that does some calculations and then outputs a voltage based on the result using analogWrite function. However my problem is that I had done my programming based ...
- 133