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This chapter of Embed with Elliot begins with a crazy rant. If you appetite to apprehend the abutting brace of paragraphs out loud to yourself with article like an American-accented Dave-Jones-of-EEVBlog whine, it apparently won’t hurt. Because, for all the acceptable Arduino has done for the Hackaday audience, there’s two aspects that absolutely get our goat.

(Rant-mode on!)

First off is the “sketch” thing. Listen up, Arduino people, you’re not autograph “sketches”! It’s code. You’re not sketching, you’re coding, alike if you’re an artist. If you abide to alarm C cipher a “sketch”, we get to accredit to our abutting watercolor sloppings as “writing buggy COBOL”.

And you’re not autograph “in Arduino”. You’re autograph in C/C , application a library of functions with a adequately constant API. There is no “Arduino language” and your “.ino” files are three curve abroad from actuality accepted C . And this obfuscation hurts you as an Arduino user and artificially blocks your advance into a “real” programmer.

(End of rant.)

Let’s booty that additional bluster a little bit actively and dig into the Arduino libraries to see if it’s Arduinos all the way down, or if there’s terra firma aloof beneath. If you started out with Arduino and you’re attractive for the abutting accomplish to booty to advance your programming chops forward, this is a affable way to breach out of the Arduino confines. Or maybe aloof to blink central the atramentous box.

Click on the “What is Arduino” box on the advanced folio of arduino.cc, and you’ll see the afterward sentence:

“ARDUINO SOFTWARE: You can acquaint your Arduino what to do by autograph cipher in the Arduino programming language…”

Navigate to the FAQ, and you’ll see

“the Arduino accent is alone a set of C/C functions that can be alleged from your code”.

Where we appear from, a agglomeration of functions accounting in a programming accent is alleged a library. So which is it, Arduino?

(The Accent Reference folio is a absolute mess, accumulation genitalia of accepted C with functions authentic in the Arduino amount library.)

Maybe that’s not as adult or advocate as claiming to accept appear up with a new programming language, but the aberration affairs and it’s a abuse acceptable affair that it’s aloof a set of libraries. Because the adorableness about the Arduino libraries is that you don’t accept to use them, and that you can aces and accept amid them. And back the libraries are accounting in absolute programming languages (C/C ), they’re a absolutely advantageous certificate if you accept those languages.

C and Assembly language, on the added hand, are altered languages. If you’re autograph assembler, you can calmly specify absolutely which of the chip’s built-in instructions to use for any accurate operation — not so in C. Storing abstracts in accurate registers in the CPU is accustomed in assembler, but ballsy in C. So if you alpha out autograph your cipher in C, and again acquisition out that you charge some of the appearance of assembler, you’re hosed. You stop autograph in C and anchorage all your cipher over to assembler. You accept to about-face languages. You don’t get to aces and choose.

(Yes, there is inline assembler in GCC.  That’s cheating.)

This is not at all the case with Arduino: it’s not a programming accent at all, and that’s a accursed acceptable thing. You’re autograph in C/C with some added accessibility libraries on top, so area the libraries suck, or they’re aloof apparent inconvenient, you don’t accept to use them. It’s that simple.

A prime archetype is digitalWrite() in the Arduino’s amount library, begin in the “wiring_digital.c” file. It’s carelessness to use the ridiculously apathetic digitalWrite() functions back acceleration or timing matters. Compared to flipping $.25 in the achievement registers directly, digitalWrite() is 20-40x slower.

The ambit shots actuality are from artlessly removing the adjournment statements from the Blink.ino archetype cipher that comes with Arduino — about toggling the LED pin at abounding speed. Upper larboard is application digitalWrite() to cast the pin state. Upper adapted is application absolute bit abetment in C: PORTB ^= (1 << LED_BIT); Because Arduino’s digitalWrite() command has a agglomeration of if...then statements in it that aren’t optimized abroad by the compiler, it runs 28 times slower.

(And worse, as you can see in the lower left, the Arduino cipher runs with casual timing glitches, because an arrest account accepted gets periodically alleged to amend the millisecond timer. That’s not a botheration with digitalWrite() per se, but it’s a admonishing back attempting bound timing application the Arduino defaults.)

OK, so digitalWrite() is no acceptable for timing-critical coding. If Arduino were a absolute language, and you were ashore with digitalWrite(), you wouldn’t be able to use the accent for annihilation decidedly sophisticated. But it’s aloof a accessibility function. So you can feel chargeless to use digitalWrite() in the setup() allocation of your cipher area it’s not acceptable to be time critical. That doesn’t beggarly that you accept to use it in the loop() allocation back timing does matter.

And what this additionally agency is that you’re no best accustomed to say “Arduino sucks”. Arduino is C/C , and at atomic C doesn’t suck. (Zing! Booty that, C lovers. De gustibus non disputandem est.) If you anticipate that some of the Arduino libraries suck, you’re absolutely activity to accept to specify which libraries in accurate you mean, or we’ll alarm you out on it, because nobody’s banishment you to use them wholesale. Indeed, if you’re coding on an AVR-based Arduino, you’ve got the absolute avr-libc activity broiled in. And it doesn’t suck.

So if Arduino is aloof C/C , what’s up with the “.ino” filetype? Why is it not “.c” or “.cpp” like you’d expect? According to the Arduino body action documentation,

“The Arduino ambiance performs a few transformations to your capital account book (the chain of all the tabs in the account after extensions) afore casual it to the avr-gcc compiler.”

True C/C appearance requires you to acknowledge (prototype) all functions that you’re activity to use afore you ascertain them, and this is usually done in a abstracted attack “.h” file. Back C compiles your code, it artlessly takes anniversary action and turns it into apparatus code. In a philosophically (and generally practically) audible step, references to a action are affiliated up with the aggregate apparatus cipher apery them. The linker, then, alone needs to apperceive the names of anniversary action and what types of variables it needs and allotment — absolutely the abstracts in the action declaration.

Long adventure short: functions charge above-mentioned acknowledgment in C, and your “.ino” cipher defines setup() and loop() but never declares them. So that’s one affair that the Arduino IDE does for you. It adds two (or more, if you ascertain added functions in your “.inos”) action prototypes for you.

The added affair the IDE’s preprocessor does is to add #include "Arduino.h" to the top of your code, which pulls in the amount Arduino libraries.

(And then, for some abstruse reason, it additionally deletes all comments from your code, authoritative it harder to alter after on. Does anyone out there apperceive why the Arduino IDE does this?)

So that’s it. Three curve (or maybe a few more) of actual simple boilerplate abstracted a “sketch” from accurate C/C code. This was apparently done in the absorption of streamlining the coding acquaintance for newbies, but accustomed that about every newb is activity to alpha off with the arrangement activity anyway, it’s not bright that this buys much.

On the added hand, the abuse done to the microcontroller newbie is analytic large. The newb doesn’t apperceive that it’s absolutely C/C beneath the covers and doesn’t apprentice annihilation about one of the best introductory, although mindless, requirements of the language(s): action declarations.

When the newb eventually does appetite to accommodate alfresco code, the newb will charge to apprentice about #include statements anyway, so ambuscade #include "Arduino.h" is inconsistent and sets up approaching confusion. In short, the newb is addled from a brace of accessible acquirements opportunities, aloof to abstain some boilerplate that’s templated out anyway.

And if you don’t accept that Arduino is C/C , try the afterward experiment:

You’ve aloof abstruse to address C/C anon from aural the Arduino IDE.

(Note: for some reason, the Arduino IDE requires a Blink.ino book to be present, alike if it’s absolutely empty. Don’t ask us.)

So if Blink.ino turns into Blink.cpp, what’s up with the setup() and loop() functions? Back do they anytime get called? And delay a minute, don’t all C and C programs charge a main() action to alpha off? You are on the aisle to enlightenment.

Have a attending at the main.cpp book in hardware/arduino/avr/cores/arduino.

There’s your main() function! And although we’ve automated the book a little bit for presentation, it’s aloof about this straightforward.

The init() action is alleged afore any of your cipher runs. It is authentic in “wiring.c” and sets up some of the microcontroller’s accouterments peripherals. Included amid these tasks on the AVR belvedere is configuring the accouterments timers for the milliseconds beat and PWM (analogOut()) functions, and initializing the ADC section. Apprehend through the init() action and the agnate sections of the AVR datasheet if you’ve never done any low-level initializations of an AVR chip; that’s how it’s done after Arduino.

And again we get to the meat. The setup() action is called, and in an amaranthine for loop, the loop() action is always called. That’s it, and it’s the aforementioned cipher you’d address in C/C for any added microcontroller on the planet. That’s the abracadabra Arduino setup() and loop(). The emperor has no clothes, and the Wizard of Oz is aloof a affecting little man abaft a curtain.

If you appetite to dig about added into the internals of the Arduino amount library, chase for “Arduino.h” on your bounded install, or hit up the amount library on Github.

So we’ve got C/C code. Accumulation it into an Arduino activity is decidedly straightforward, and it’s well-documented in the Arduino docs wiki. But if you aloof appetite to see for yourself, go into Preferences and accredit bombastic logging during compilation. Now the absolute body action will beam by you in that little window back you bang “Verify”.

It’s a lot to booty in, but it’s about all repetitive. The compiler isn’t accomplishing annihilation aberrant or different at all. It’s accumulation all of the functions in the Arduino amount files, and putting the consistent functions into a big (static) library file. Again it’s demography your cipher and this library and bond them all together. That’s all you’d do if you were autograph your own C/C code. It’s aloof that you don’t apperceive it’s accident because you’re acute article that looks like a comedy button on an old Walkman. But it’s not rocket science.

There is one added detail here. If you accommodate a library book through the menu, and it’s not allotment of the amount Arduino libraries, the IDE locates its antecedent cipher and compiles and links it in to the amount library for you. It additionally types the #include band into your “.ino” file. That’s nice, but hardly a deal-breaker.

If you’d like to see this body action in the anatomy of a Makefile, here’s (our) archaic adaptation that’s added aimed at understanding, and this adaptation is added adapted for assembly use.

If the Arduino is the anchored electronics world’s aperture drug, what are the abutting accomplish that the Arduino programmer should booty to become a “real” anchored programmer carve oil-burning heroin junkie? That depends on you.

Are you already acceptable at coding in a lower-level accent like C/C ? Again you charge to focus on the microcontroller-specific ancillary of things. You’re in abundant appearance to aloof dive into the Arduino codebase. Try to booty a few of the archetype pieces, or alike some of your own “sketches” and attending through the included Arduino library’s antecedent code. Re-write some simple cipher alfresco the IDE and accomplish abiding that you can articulation to the Arduino amount code. Again alter $.25 of the amount with your own cipher and accomplish abiding it still works. You’ll absorb bisected of your time attractive into the accordant micro’s datasheet, but that’s acceptable for you.

Are you adequate with electronics but addled by coding? You ability absorb a bit of time acquirements article like C. Apprentice C the Hard Way is phenomenal, and although it’s aimed at association alive on bigger computers, it’s got a lot of the accomplishments that you’ll charge to advance through and above the Arduino codebase. You’re activity to charge to apprentice about the (relatively trivial) accent conventions and boilerplatey being to get adequate in beeline C/C , and again you can dig in to the Arduino source.

Wherever you are, bethink that Arduino isn’t a language: it’s a set of libraries accounting in C/C , some of them absolutely absolutely good, and some of them (we’re attractive at you EEPROM) artlessly C wrappers on the existant avr-libc EEPROM library. And that agency that for every Arduino activity you’ve written, you’ve got the agnate antecedent cipher sitting about in C/C , accessible for you to dig into. Thank advantage they didn’t ad-lib their own programming language!

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