5 Myths Everyone Believes about Arduino (that aren’t true)

Having spent the past 6 years writing code for the Arduino platform, I’ve noticed a trend in myths from both new-comers and veteran users. Here are the Top 5 Myths I see come up on forums, in classes, and on IRC.

1. The Arduino uses its own Language

This myth isn’t helped by the Arduino.cc home page which says

“The microcontroller on the board is programmed using the Arduino programming language.

While it is true that the structure of an Arduino sketch looks unique, it is really just C++ with a tiny bit of preprocessing. Users writing “Arduino Code” are actually writing C++ with, what I call, the Arduino Library. Functions like digitalWrite() are just that, C++ functions.

So while the Arduino Library does a great job of making microcontroller programming very simple, it is not its own language.

2. Pin 13 Has a Resistor

Countless tutorials have lulled newbies into this trap. The very first Arduino board, of which something like 200 were produced, had a LED and series resistor on Pin 13. That’s the only board which did. So you should never never never connect a LED to Pin 13, without a resistor!

Update: Clarification. There *is* a resistor on Pin 13. However, it is only connected to the LED that is in series with it to ground. So that resistor does *nothing* to protect anything you attach to the pin, like your own LED.

3. Commercial products don’t use Arduino

Corollary: “real” engineers don’t use Arduino!

Okay. I try not to toot this horn, but I’m a “real engineer.”  You already know that: it’s in my twitter name and URL. Here’s a top secret piece of information:  I use Arduino. Now it is true. You aren’t going to go to Best Buy or your local big-box electronics store and find any products that have an “Arduino Inside” sticker. However, Arduino is a prototyping platform. You aren’t going to ship an Uno with every product. You might, however, develop a product with an Arduino and embed the ATmega328 inside of it. Or, more likely, you’ll prototype the idea, run it through a crowd funding effort and then redesign.

You have to define what “commercial” means, but there are plenty of products out there that started with an Arduino in the early stages.

Ever hear of 3D printers?

4. analogWrite() is Analog

This one catches a lot of people who don’t really understand Pulse-Width Modulation. With the exception of the “Due”, Arduino boards do not output “analog” signals. (Note, you might want to watch this video on the difference between Analog and Digital.)

PWM signals are actually digital signals, where you change the length of time between the “on” and “off” states.

5. The Header Spacing was a mistake (or it wasn’t.)

If you know anything about the Arduino pinout, you should know that the spacing between pins 7 and 8 isn’t 0.1″ (or 2.54mm). At one point the Arduino web site had this in the FAQ as an “eleventh hour” mistake. Then there was the explanation that it prevented shields being plugged in backwards. Now, I’m not sure if it was intentional, but it is true that a benefit of the spacing is that you can’t plug in a shield backwards.

The perceived downside to this decision is that it makes the board difficult to plug into a breadboard, or a shield into a breadboard. However, magic jumper wires do exist which solve this “problem.”

Okay, so those are the 5 Myths I encounter most.

Question: What other myths have you heard or helped to dispel? You can leave a comment by clicking here.

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62 thoughts on “5 Myths Everyone Believes about Arduino (that aren’t true)

  1. Strictly speaking, I think the Arduino language is based on the Processing language, which itself is a simplified form of C++. /nitpick 🙂

  2. #2 is wrong. I have 3 Arduino boards. A Duemilanove, an Uno and a Mega and ALL of them have an LED and series resistor tied to pin 13.

    • I can confirm that the Arduino Uno schematics show a 1k resistor on the SCK (pin 13). However, I think it’s for the LED that’s also linked to the pin.. not for additional loads.

    • Yes, but that resistor is ONLY limits current to the LED onboard. It does nothing to protect additional loads connected to the pin.

      The resistor and LED is in parallel with the pin header.

      • That’s a good clarification – the onbord LED DOES have a current limiting resistor, but this resistor is NOT in series with the off-board connector.

  3. One of the biggest myths I’ve encountered is the assumption that you have to use one whole Arduino board for a project. In my experience it’s better to use the board for testing and debugging and then flash an atmega chip with your sketch. Then you can integrate the chip into your design on a perf board. It may be a little more work and you lose the ability to use shields but it makes for a cleaner and smaller profile. (Plus it’s cheaper)

    • I’ve seen that a lot, you can get ATMega328 chips flashed with the Arduino Bootloader for just under £3. I’ve done several projects where I’ve prototyped with an Arduino and then etched my own PCB.

      You don’t really need much to get an ATMega328 to run, all you need is a couple of capacitors, a crystal and a datasheet with the pinouts of the 328 and you are sorted. I have built arduino ‘clones’ on stripboard with a 5V regulator, the process is trivial and inexpensive and shouldn’t really cost more than £5 to achieve.

  4. Dose anyone has an information about how to move from Arduino to real commercial product? I’ve been searching for a long time but it seems not much clue on it.

    • You might be over thinking it. Im not sure such leap exist.
      You design a product with an atmega chip inside and program it with any other programmer . You can even order hundreds of chips preprogrammed.
      You can even cheat and load the arduino bootloader and run the same code you already created i believe this is known as a arduino clone. Same skills you just use the exact amount of hardware you need. No extra headers no shields
      This should be faster end cheaper.

      • I have done this quite a few times as part of my learning process of arduino and electronics.

        I prototype on arduino, then make a custom board with a 328 inside and good old soldering.

        My latest project, I burn my own bootloader on a 328 chip and put it on a breadboard and load my programs from the arduino software directly via a usb-serial adaptor or directly through icsp.
        Once my dev work was done, I soldered everything on a prototype pcb board (hours of soldering).

        If I wanted to comercialize the product I would make a PCB design and send it to a pcb fab.


  5. Can confirm, am engineering student, have used arduino to prototype a setup with Atmega328 for use in my Sr. Design project.

  6. I have taken stage equipment apart before and been surprised to find an atmega 328 as the microprocessor, the product was a dmx hazer, that was a commercial application

        • There is really no way of knowing.

          Arduino requires the bootloader to be programmed first.

          So if the bootloader is not there, the Arduino IDE will not work.

          Also, if the 328p is soldered down, there will be a small chance to get the bootloader programmed into that chip.

          • > Arduino requires the bootloader to be programmed first. So if the bootloader is not there, the Arduino IDE will not work.

            That’s not true. For one thing, the Arduino IDE works whether or not an Arduino is connected in any way. Second, you can program “via an ICSP” (see File Menu -> Upload Using Programmer).

            Alternatively, you can take the .hex file from an Arduino IDE compile, and upload that using other methods (eg. avrdude).