Arduino Stack Exchange: Questions and Answers

761 Pages·2016·15.54 MB·English

by  Duckett

Table of Contents
About this book
Arduino Uno (85 questions)
Programming (37 questions)
Serial (36 questions)
C++ (21 questions)
Sensors (19 questions)
Pins (15 questions)
Uploading (14 questions)
Library (14 questions)
Timers (13 questions)
Power (12 questions)
ATMega328 (12 questions)
Compile (11 questions)
Shields (11 questions)
Arduino Mega (11 questions)
Arduino Ide (10 questions)
Interrupt (10 questions)
LED (9 questions)
PWM (9 questions)
C (9 questions)
Avrdude (9 questions)
Battery (8 questions)
IDE (8 questions)
Motor (8 questions)
Voltage Level (8 questions)
Attiny (8 questions)
Arduino Yun (7 questions)
Safety (7 questions)
Arduino Nano (7 questions)
AnalogRead (7 questions)
LCD (6 questions)
Arduino DUE (6 questions)
Sketch (6 questions)
Hardware (6 questions)
Bootloader (5 questions)
Time (5 questions)
Software (5 questions)
I2c (5 questions)
Button (5 questions)
Memory Usage (5 questions)
Linux (4 questions)
Clones (4 questions)
Variables (4 questions)
Flash (4 questions)
EEPROM (4 questions)
Sram (3 questions)
Arduino Uno SMD (3 questions)
Temperature Sensor (3 questions)
PROGMEM (3 questions)
Electricity (3 questions)
GSM (3 questions)
Emulation (2 questions)
Enclosure (2 questions)
Tcpip (2 questions)
Oscillator Clock (2 questions)
IR (2 questions)
Web Service (1 question)
Project (1 question)
RFID (1 question)
Osx (1 question)
Copyright
About this book
This book has been divided into categories where each question belongs to one
or more categories. The categories are listed based on how many questions they
have; the question appears in the most popular category. Everything is linked
internally, so when browsing a category you can easily flip through the questions
contained within it. Where possible links within questions and answers link to
appropriate places within in the book. If a link doesn't link to within the book,
then it gets a special icon, like this .
Arduino Uno
Questions
Q: Is an Arduino capable of running 24/7?
Tags: arduino-uno (Next Q)
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 with a simple
outlet power supply 5V @ 1A.
My Questions:
Will I have any problems leaving the Arduino turned on all the time?
Is there some other Arduino board better recommended for this?
Are there any precautions that I need to heed regarding this?
Tags: arduino-uno (Next Q)
User: butzke
Answer by sachleen
You shouldn't have any issues keeping it on all the time, however, some thing to
consider is any counters you may have, like the use of millis().
From the Arduino docs on millis :
This number will overflow (go back to zero), after approximately 50 days.
So for projects that are on for long periods of time, you may not see an issue
immediately but something like this could pop up and cause errors down the
road.
Answer by matthew-g.
A couple of things to keep in mind (outside of @Sachleen's mention of Milli's):
Like any electronics, heat can be disruptive. The microcontroller itself isn't
likely going to be a huge issue from the perspective of heat, but other
components like the power supply might cause issues.
If your code uses EEPROMWrite , be aware that the EEPROM is only
rated for something in the neighbourhood of 100,000 writes.
Answer by thedoctor
Keep in mind that the flash and EEPROM have limited lifetimes (about 10,000
read/write cycles) so if you're doing a lot of reading and writing to those, they
may become corrupted. In a test I did, an external EEPROM took about 3 days
to start becoming corrupted.
Tags: arduino-uno (Next Q)
Q: How to pause Arduino for 1 millisecond through MATLAB?
Tags: arduino-uno (Prev Q) (Next Q)
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 synchronize all the
components [like the Arduino].
I am able to send pulses to my stepper-motor just by using:
void loop() {
digitalWrite(2, HIGH);
delay(1);
digitalWrite(2, LOW);
delay(1);
}
This works fine, and will make the motor move about once every 2 milliseconds.
My problem is that I cannot find a way to produce this same delay through
MATLAB's interface. I do know that MATLAB has a pause() function, but
when I set up a loop in MATLAB like this:
a = arduino('COM4');
for m = 1:400
a.digitalWrite(2, 1);
pause(0.001);
a.digitalWrite(2, 0);
pause(0.001);
end
Each step takes WAY longer - about 200 milliseconds each.
What are other options for creating the pause between digital High / Low being
sent to the Arduino? It would be nice if I could control the outcome from
Matlab, through Arduino.
Tags: arduino-uno (Prev Q) (Next Q)
User: radical-fanatic
Answer by mpflaga
The increased in observed delay is due to the time it takes to send the command
from MATLAB to the Arduino have its code execute the requested command. In
your case the a.digitalWrite. So actual time between pulses using MATLAB's
delay is 0.001 pause plus the time of baud rate times the packet size and
decoding then execution.
I would recommend not pursuing this solution of the MATLAB controlling the
timing of Step Motors, remotely. As this latent coupling will be a frustrating
limitation. Noting that for step motors the timing can not afford such latent
execution. Hence all the 3D printers and many CNC with Step Motors use
Arduino's which get G-Code (motor move commands with destinations) and the
Real-time firmware handles the stepping, within tolerances.
I would suggest using something like grbl firmware with step motor shield and
then have the MATLAB send the needed G-code. Where there are others with
much more features but tailored to 3d Printing. grbl is simpler and straight to the
point of moving motors.
Tags: arduino-uno (Prev Q) (Next Q)
Q: How do I figure out if my board is approaching end of life?
Tags: arduino-uno (Prev Q) (Next Q), safety (Next Q)
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 would like to be sure that the board is not
approaching end of life or going to fail anytime soon. Is there any reliable way to
figure out how long the board will function without failing or reduction in
performance?
Tags: arduino-uno (Prev Q) (Next Q), safety (Next Q)
User: asheeshr
Answer by connor-wolf
Unfortunately, there isn't much way to really determine "wear" in the context of
solid-state electronics.
Probably the things that are most likely to fail are the electrolytic capacitors and
the connectors.
First, if you're using an ATmega CPU for something that could possibly injure
someone CONTACT ATMEL AND TALK ABOUT SAFETY
PRECAUTIONS. The ATmega CPU used in most of the arduino models is not
rated for use in such situations.
In EVERY datasheet:
Atmel products are not intended, authorized, or warranted for use as
components in applications intended to support or sustain life.
Now, realistically, this is probably mostly lawyer repellent, but you should still
take appropriate precautions.
Really, while there isn't anything on a common arduino board that really wears
out except the connectors, why are you trying to save $30 at a potential huge
cost? Just buy a new board.
I'd also strongly reccomend you chose a board with a SMT ATmega328P, since
that removes the IC socket contacts from the list of concerns. If possible, also
remove the pin-headers, and solder wires to the board directly. Try to minimize
connectors, since they are frequent points of failure.
Answer by asheeshr
One of the sections of the Arduino that is likely to become unreliable over time
is its memory. There are three pools of memory in the microcontroller used on
avr-based Arduino boards:
Flash memory (program space), is where the Arduino sketch is stored.
SRAM (static random access memory) is where the sketch creates and
manipulates variables when it runs.
EEPROM is memory space that programmers can use to store long-term
information.
The memory is one part of the board that can be checked and verified, and thus
evaluated for reliability/health. A very basic way to check memory would be to
write a certain 8-bit pattern (byte character) over every address in the memory
and then read the value present from every address. If the value that was written
matches the value that is read, then that specific 8 bit block in memory is
functioning correctly at the present moment.
Wear in ROM memory usually occurs in a blockwise pattern i.e. n*8-bit blocks
become degraded over time. So, for a 2K byte ROM chip, the health of the chip
can be estimated by writing and reading from every byte on the chip, and
calculating the percentage of correctly functioning blocks. If the percentage of
failed blocks is significant (15%-20%), that means that the memory is likely to
fail soon.
The test code can be written using separate methods for each of the memory
sections.
SRAM
Any variables declared statically or dynamically are allocated on the SRAM. So,
Any variables declared statically or dynamically are allocated on the SRAM. So,
we could declare a large character array (~2000) and fill every element with 255
(all bits 1). Then, we could attempt to read each of those elements and see if the
value being read is indeed 255.
EEPROM
The EEPROM can be manipulated using the EEPROM library . The library
provides functions to read and write from specific locations in the EEPROM. So,
all memory addresses can be tested by simply looping over the entire memory
space. This operation will require 500 writes and reads.
Depending on the board usage, EEPROM is most likely to fail first but is not
critical to board operation.
Flash
Data can be stored on the flash memory using the PROGMEM directive. Similar
to SRAM, a large array can be declared and initialized here. Then, values can be
read and checked.
Tags: arduino-uno (Prev Q) (Next Q), safety (Next Q)
Q: Does Arduino Uno R3 require cooling in a closure?
Tags: arduino-uno (Prev Q) (Next Q), enclosure (Next Q)
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 generated, but with no ventilation except
some slits in the enclosure, there won't be much air circulation without a fan. My
concern with adding a fan was the fact that I'd need to power it.
Tags: arduino-uno (Prev Q) (Next Q), enclosure (Next Q)
User: b.k.
Answer by jippie
The only times I had an AVR run hot was when I applied reverse power to it.