This installment of Embed with Elliot begins with a crazy rant. If you want to read the next couple of paragraphs out loud to yourself with something like an American-accented Dave-Jones-of-EEVBlog whine, it probably won’t hurt. Because, for all the good Arduino has done for the Hackaday audience, there’s two aspects that really get our goat.

(Rant-mode on!)

First off is the “sketch” thing. Listen up, Arduino people, you’re not writing “sketches”! It’s code. You’re not sketching, you’re coding, even if you’re an artist. If you continue to call C++ code a “sketch”, we get to refer to our next watercolor sloppings as “writing buggy COBOL”.

And you’re not writing “in Arduino”. You’re writing in C/C++, using a library of functions with a fairly consistent API. There is no “Arduino language” and your “.ino” files are three lines away from being standard C++. And this obfuscation hurts you as an Arduino user and artificially blocks your progress into a “real” programmer.

(End of rant.)

Let’s take that second rant a little bit seriously and dig into the Arduino libraries to see if it’s Arduinos all the way down, or if there’s terra firma just beneath. If you started out with Arduino and you’re looking for the next steps to take to push your programming chops forward, this is a gentle way to break out of the Arduino confines. Or maybe just to peek inside the black box.

Arduino is C/C++

Click on the “What is Arduino” box on the front page of arduino.cc, and you’ll see the following sentence:

“ARDUINO SOFTWARE: You can tell your Arduino what to do by writing code in the Arduino programming language…”

Navigate to the FAQ, and you’ll see

“the Arduino language is merely a set of C/C++ functions that can be called from your code”.

Where we come from, a bunch of functions written in a programming language is called a library. So which is it, Arduino?

(The Language Reference page is a total mess, combining parts of standard C with functions defined in the Arduino core library.)

Maybe that’s not as sexy or revolutionary as claiming to have come up with a new programming language, but the difference matters and it’s a damn good thing that it’s just a set of libraries. Because the beauty about the Arduino libraries is that you don’t have to use them, and that you can pick and choose among them. And since the libraries are written in real programming languages (C/C++), they’re a totally useful document if you understand those languages.

C and Assembly language, on the other hand, are different languages. If you’re writing assembler, you can easily specify exactly which of the chip’s native instructions to use for any particular operation — not so in C. Storing data in particular registers in the CPU is normal in assembler, but heroic in C. So if you start out writing your code in C, and then find out that you need some of the features of assembler, you’re hosed. You stop writing in C and port all your code over to assembler. You have to switch languages. You don’t get to pick 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 language at all, and that’s a darned good thing. You’re writing in C/C++ with some extra convenience libraries on top, so where the libraries suck, or they’re just plain inconvenient, you don’t have to use them. It’s that simple.

A prime example is digitalWrite() in the Arduino’s core library, found in the “wiring_digital.c” file. It’s madness to use the ridiculously slow digitalWrite() functions when speed or timing matters. Compared to flipping bits in the output registers directly, digitalWrite() is 20-40x slower.

The scope shots here are from simply removing the delay statements from the Blink.ino example code that comes with Arduino — essentially toggling the LED pin at full speed. Upper left is using digitalWrite() to flip the pin state. Upper right is using direct bit manipulation in C: PORTB ^= (1 << LED_BIT); Because Arduino’s digitalWrite() command has a bunch of if...then statements in it that aren’t optimized away by the compiler, it runs 28 times slower.

(And worse, as you can see in the lower left, the Arduino code runs with occasional timing glitches, because an interrupt service routine gets periodically called to update the millisecond timer. That’s not a problem with digitalWrite() per say, but it’s a warning when attempting tight timing using the Arduino defaults.)

OK, so digitalWrite() is no good for timing-critical coding. If Arduino were a real language, and you were stuck with digitalWrite(), you wouldn’t be able to use the language for anything particularly sophisticated. But it’s just a convenience function. So you can feel free to use digitalWrite() in the setup() portion of your code where it’s not likely to be time critical. That doesn’t mean that you have to use it in the loop() portion when timing does matter.

And what this also means is that you’re no longer allowed to say “Arduino sucks”. Arduino is C/C++, and at least C doesn’t suck. (Zing! Take that, C++ lovers. De gustibus non disputandem est.) If you think that some of the Arduino libraries suck, you’re really going to have to specify which libraries in particular you mean, or we’ll call you out on it, because nobody’s forcing you to use them wholesale. Indeed, if you’re coding on an AVR-based Arduino, you’ve got the entire avr-libc project baked in. And it doesn’t suck.

The “.ino” is a Lie

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

“The Arduino environment performs a few transformations to your main sketch file (the concatenation of all the tabs in the sketch without extensions) before passing it to the avr-gcc compiler.”

True C/C++ style requires you to declare (prototype) all functions that you’re going to use before you define them, and this is usually done in a separate header “.h” file. When C compiles your code, it simply takes each function and turns it into machine code. In a philosophically (and often practically) distinct step, references to a function are linked up with the compiled machine code representing them. The linker, then, only needs to know the names of each function and what types of variables it needs and returns — exactly the data in the function declaration.

Long story short: functions need prior declaration in C, and your “.ino” code defines setup() and loop() but never declares them. So that’s one thing that the Arduino IDE does for you. It adds two (or more, if you define more functions in your “.inos”) function prototypes for you.

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

(And then, for some mysterious reason, it also deletes all comments from your code, making it harder to debug later on. Does anyone out there know why the Arduino IDE does this?)

So that’s it. Three lines (or maybe a few more) of very simple boilerplate separate a “sketch” from valid C/C++ code. This was presumably done in the interest of streamlining the coding experience for newbies, but given that almost every newb is going to start off with the template project anyway, it’s not clear that this buys much.

On the other hand, the harm done to the microcontroller newbie is reasonably large. The newb doesn’t know that it’s actually C/C++ underneath the covers and doesn’t learn anything about one of the most introductory, although mindless, requirements of the language(s): function declarations.

When the newb eventually does want to include outside code, the newb will need to learn about #include statements anyway, so hiding #include "Arduino.h" is inconsistent and sets up future confusion. In short, the newb is blinded from a couple of helpful learning opportunities, just to avoid some boilerplate that’s templated out anyway.

Write C++ Directly in the Arduino IDE

And if you don’t believe that Arduino is C/C++, try the following experiment:

1. Save a copy of the example Blink project.
2. Go into the “sketch’s” directory and copy Blink.ino to Blink.cpp.
3. Re-open the project in Arduino and delete everything from Blink.ino
4. Add the required boilerplate to Blink.cpp. (One include and two function declarations.)
5. Verify, flash, and whatever else you want.

You’ve just learned to write C/C++ directly from within the Arduino IDE.

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

main.cpp

So if Blink.ino turns into Blink.cpp, what’s up with the setup() and loop() functions? When do they ever get called? And wait a minute, don’t all C and C++ programs need a main() function to start off? You are on the path to enlightenment.

Have a look at the main.cpp file in hardware/arduino/avr/cores/arduino.

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

The init() function is called before any of your code runs. It is defined in “wiring.c” and sets up some of the microcontroller’s hardware peripherals. Included among these tasks on the AVR platform is configuring the hardware timers for the milliseconds tick and PWM (analogOut()) functions, and initializing the ADC section. Read through the init() function and the corresponding sections of the AVR datasheet if you’ve never done any low-level initializations of an AVR chip; that’s how it’s done without Arduino.

And then we get to the meat. The setup() function is called, and in an endless for loop, the loop() function is continually called. That’s it, and it’s the same code you’d write in C/C++ for any other microcontroller on the planet. That’s the magic Arduino setup() and loop(). The emperor has no clothes, and the Wizard of Oz is just a pathetic little man behind a curtain.

If you want to dig around more into the internals of the Arduino core library, search for “Arduino.h” on your local install, or hit up the core library on Github.

The Arduino Compile Phase

So we’ve got C/C++ code. Compiling it into an Arduino project is surprisingly straightforward, and it’s well-documented in the Arduino docs wiki. But if you just want to see for yourself, go into Preferences and enable verbose logging during compilation. Now the entire build process will flash by you in that little window when you click “Verify”.

It’s a lot to take in, but it’s almost all repetitive. The compiler isn’t doing anything strange or unique at all. It’s compiling all of the functions in the Arduino core files, and putting the resulting functions into a big (static) library file. Then it’s taking your code and this library and linking them all together. That’s all you’d do if you were writing your own C/C++ code. It’s just that you don’t know it’s happening because you’re pressing something that looks like a play button on an old Walkman. But it’s not rocket science.

There is one more detail here. If you include a library file through the menu, and it’s not part of the core Arduino libraries, the IDE locates its source code and compiles and links it in to the core library for you. It also types the #include line into your “.ino” file. That’s nice, but hardly a deal-breaker.

If you’d like to see this build process in the form of a Makefile, here’s (our) primitive version that’s more aimed at understanding, and this version is more appropriate for production use.

Next Steps

If the Arduino is the embedded electronics world’s gateway drug, what are the next steps that the Arduino programmer should take to become a “real” embedded programmer slash oil-burning heroin junkie? That depends on you.

Are you already good at coding in a lower-level language like C/C++? Then you need to focus on the microcontroller-specific side of things. You’re in great shape to just dive into the Arduino codebase. Try to take a few of the example pieces, or even some of your own “sketches” and look through the included Arduino library’s source code. Re-write some simple code outside the IDE and make sure that you can link to the Arduino core code. Then replace bits of the core with your own code and make sure it still works. You’ll spend half of your time looking into the relevant micro’s datasheet, but that’s good for you.

Are you comfy with electronics but bewildered by coding? You might spend a bit of time learning something like C. Learn C the Hard Way is phenomenal, and although it’s aimed at folks working on bigger computers, it’s got a lot of the background that you’ll need to progress through and beyond the Arduino codebase. You’re going to need to learn about the (relatively trivial) language conventions and boilerplatey stuff to get comfortable in straight C/C++, and then you can dig in to the Arduino source.

Wherever you are, remember that Arduino isn’t a language: it’s a set of libraries written in C/C++, some of them really quite good, and some of them (we’re looking at you EEPROM) simply C++ wrappers on the existant avr-libc EEPROM library. And that means that for every Arduino project you’ve written, you’ve got the equivalent source code sitting around in C/C++, ready for you to dig into. Thank goodness they didn’t invent their own programming language!

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I recently recieved lots of Cybot parts from my friend who collected the parts of eBay, no longer wanting them he kindly gave them to me, my plan was to convert it to an Arduino based robot.

If you are not aware what a Cybot looks like here is a picture I took before the dismantling process:

The Cybot had some good features; line following, IR remote control, speech recognition and even the ability to find its IR ball and shoot goals into an IR goal.

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This Legos robotic project uses JAVA sockets to communicate to an onboard Arduino which controls servomotors, LED's, and drive motors. It features a wireless IP Camera and was a lot of fun to build.

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This is my version of the "start here" robot. For me this was a programming exercise. I had written an obstacle avoiding sketch for my Rover 5. It worked but I was never really happy with it. Most code that I've seen online uses lots of delays in the code. Some time ago I swore to myself to never use the delay function in void loop ever again. There are various reasons for it, once you start writing more advanced code the delay function can cause lots of trouble. I also use a library (RF24network) in another project where I can not use the delay function.

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The Arduino IDE is extremely similar to C++, but judging from the sketches you can find on the Internet, you’d never know it. Simpler Arduino projects can make do with just toggling IO pins, reading values, and sending serial data between two points. More complex builds fall into the category of real software development, and this is where the standard Arduino IDE falls miserably short.

[Andy] saw this lack of proper libraries for more complicated pieces of software as a terrible situation and decided to do something about it. He ported the SGI Standard Template Library to bring all those fun algorithms and data structures to any AVR chip, including the Arduino.

Going over what’s included in [Andy]‘s port reads just like a syllabus for an object-oriented programming class. Stacks, queues, and lists make the cut, as do strings and vectors. Also included is just about everything in the   and headers along with a few Arduino-oriented additions like a hardware serial and liquid crystal streams.

With all these objects floating around, [Andy] says it will make an impact on Flash and SRAM usage in an AVR. Still, with all the hullabaloo over faster and larger ARM micros, it’s nice to see the classic 8-bit microcontroller becoming a bit more refined.

It’s about right time to release one more “remix” for one of my blog, published almost a year ago. I haven’t got much comments, not many as I was expecting, on a topic. There are some reasons, that would explain this phenomenon, but I would better to start outlining what I did in new release, and some of you who tried old version would be impressed by progress I’ve made!

Basic structure was left almost intact. Essential parts of the project: Filtering 2D and Cross-Correlation are the same, so please read my old post, if you come across this one w/o seen it first. What differs is “preprocessing”, before we get to the filtering stage. In first, I ported a code on Leonardo board.  The easiness of connecting electret mic to Leonardo, just didn’t give me a choice!  I played already with Leonardo ADC – electret mic’s in my previous post, and would assure you, that this guys were designed to work as a team. Uno followers have to solder a pre-amplifier, not big deal, the same time not really interesting.  Code would run on Uno, except Timer and ADC settings, which you could always “copy/paste” from the old version. Feel free, be my guest.

Analog front-end is absolutely the same as I used in Sound Localization project. You would need only one mic here, just reduce the number of electrical components down.

Sampling subroutine based on Timer 4, and arduino Leonardo internal PGA set to gain x40. There are a comments in the code, so you could adjust gain up or down depends on the sensitivity of mic you have.

Windowing LUT is slightly modified Hamming/Hann cosine function,  I’d say my table is an “intermediate” version of both mention inventors.

FFT is my best achievements of this year, RADIX-4.  Compare to old code, about 3x faster. This is why I was able to increase FFT_SIZE up to 128,  still having plenty of time.  Magnitude calculation is based on approximation, very fast, because no square root extraction required. Accuracy, in the worst case scenario ~95%, which is more than enough in this project.

I changed Non-Linear compression algorithm, as now there are more Bins – 64 to pack in 16 Bands. Math is simple, and hope doesn’t need an extensive comments. Packing is necessary due memory limits, 1 sec password in current configuration (16 bands with sampling rate 4 kHz) occupied 1 kByte, full size of EEPROM on Leonardo or Uno boards.

Command Line Interface is preserved. Here is the instructions, how to set everything up and running.

And here how spectrogram looks like in LibreOffice, test phrase “Front right”, (OS Linux Ubuntu, 12.04):

Instructions.

 Get your microphone wired / connected? All checked at least a couple times with multimeter, voltages looks o’k? Good, now you are ready to start! ( Don’t forget to upload a sketch to your arduino / Leonardo -);

1. X. First of all, open serial monitor window, and check boadrate.
Should be 115200. Next, type “x” and Enter. Get some response? Does
it look like a table? Excellent, data you are looking at is “raw” 
sampling data. Probably, just noise, acoustical or electrical. 

2. F. Second test, type “f” - Enter. Again, arduino would print out 
a table. This time data represent “processed” by FFT analog signal. 
Each bin corresponds to frequency range 32 Hz. If you have a signal
generator , it's right time to do a detailed check up microphone, 
wiring, and software. If don't have, you can use your computer's 
sound card and some program, there are plenty of them available 
on-line free of charge. Connect generator to PC USB speackers, and
run a single tone, anything in audible range 16 – 2000 Hz. Check 
again using “f” command, if arduino registers a signal, and it's in
right bin. Due “windowing” function, even pure single tone would 
show up at least in 2-3 neighboring bins. Amplitude depends on 
sensitivity of the mic, and volume of the sound. Sending “x” you can 
confirm, that there is no “clipping” too many “– 511” or “+511”.

3. S. Next, if all goes well till this step, you probably already
notice, that whenever a mic picking-up a sound – yellow on-board LED
lights up. Now, it's better shutdown your TV, iPad, radio. 
Make your environment as quite as possible. Try to say something 
with your own voice, and see if led lighting up when you start 
talking, and than after ~1 sec it goes off. Repeat a few times, 
adjusting a volume and / or distance to the mic, so led goes “on/off”
reliable. Send “s” command when led is off. Don't worry, it should 
be no report on screen, till you say a word. Procedure is simple, 
send “s” - say something. After you talk, and get a printing, look 
carefully. Your objective, is get a “spectrogram” which consist of 
a few spots / blobs of digits, randomly distributed all over the 
“surface”. Repeat a few times with one word, than try another one 
and so on. With short words, very likely reporting data would be 
concentrated at the top ( you may need to scroll up to see the 
beginning), if this is a case, better to choose longer words or talk
in slower tempo. Just remember, there are three dimension, time, 
frequency and volume. You can use a signal generator here again, 
spectrogram should looks like a vertical line, may be 2 - 3 parallel
lines on low frequencies test tones. 
 Changing a frequency, you can even get some curves. What is 
important, the must be no negative numbers. If you see them – 
"overloading" happens, Decrease a volume. Dynamic range is limited 
by 127, more close you can get to this value w/o negatives, 
the better. And last dimension is a frequency. For man, it would 
be a little bit hard to “detach” a spectrogram from the left border.
It's true for everyone, who is not opera singer, me no exceptions.... 

4. R and G. After you practice enough, and received Manny nice 
looking spectrograms, it's time to check with arduino, if it's 
agree with you / thinks similar. Send “r” - recording, and say 
a word you've get your best spectrum with. Wait a few seconds, 
writing to EEPROM takes time. Now send a “g” and say the same word.
In the same manner, tonality and volume. See on the outputs, what 
is the cross-correlation factor you received. More than 50% - very 
good for beginning. Less – try again a few more times sending “g” and
repeating same word, maybe slightly varying pronunciation. Try to 
reach best recognition, “crack” your own password code! 
( note: Negatives number on “G” reports-form must be present.)
If no luck try another password code. Now you know the drill: 
S – repeat, repeat, repeat....., R, G – repeat, repeat, repeat..... 
(joke). Can't get good match? Try your computer's test sounds, 
beeps, horns, clicks, barks – whatever your OS has. It doesn't have
to be shorter than 1 sec, but only 1 second in the beginning 
would be stored / compared. My computer is able to repeat the same 
sound track (speakers test - "front right") with enormously high 
cross-factor 99 % ! I'm not a computer, my best short 86 % so far...

5. P. This command is simply reading the content of the EEPROM, 
so you always can verify, what you stored last time. 
Editing / formatting this data you can store a table in the arduino 
FLASH memory using PROGMEM. About 10 – 15 commands. Of course, 
storing data in external SD card or EEPROM, could greatly increase
the “vocabulary”, the same time design of fast cross-correlation 
algorithm with multiple “pattern”s would be another brain teasing
puzzle -);.

Have fun!

Link to arduino sketch, VOR (VOice Recognition).

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This is BrutBot.

He is my first robot and is based on the Arduino UNO with the Adafruit motor shield and a Parallax ping))) sensor.  I started with a "start here" kit but grew impatient with fried picaxe chips and infrared sensors, so I decided to try Arduino with an ultrasonic sensor instead.  

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Hamster tracker is a project that came from a hamster forum, my GF reads. A guy there had put a bike computer on his the hamster wheel to measure the speed.

I thought that I could do that in a bit more complicated way. So I started to figure out, what we needed and the speed would just not do it for me. So I thought that the proper way to it, would be to store all the runs in a database, for later analysis. This would also make it possible to display some info on the internet.

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Still lots to do, but I finally got this guy printed and assembled. He has 3DOF per leg using cheap 9g servos :( I'm using Inverse kinematics for his movement. I just started programming him and got the IK working for one leg. The ping((( is just stuck in the mega2560 for now. I'll be adding a tilt/pan head when I get more servos, and the wiring needs some cleaning up :p I just found out about LMR last week and so far it's awesome! Hopefully by the end of next weekend I'll have some walk sequence video to show off.

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In Insert Coin, we look at an exciting new tech project that requires funding before it can hit production. If you'd like to pitch a project, please send us a tip with "Insert Coin" as the subject line.

What does microcontroller programming have in common with Tetris? Quite a bit if you're doing it with Modkit Micro from a Kickstarter project out of Cambridge, MA., which allows almost anyone to visually set up their hardware using graphical blocks to write the code. The partially-hooded trio behind it promises that the software is ideal for use with protyping boards from Arduino, Evil Mad Science, Lilypad, Seeed Studio, Wiring and SparkFun, and they even claim that elementary school students have used it to "take their projects from concept to reality in just a few hours." Purists should have no fear either: you can still get into a code view to see what's going on behind the scenes. A web-based Modkit Micro is being offered online starting June 1st for $25, and there'll be a desktop variant for Windows, OSX, and Linux as early as July if they reach their funding target. Check out the video after the break and then try to get your kids to wait for college before inventing version 2.0 of this.

Continue reading Insert Coin: Modkit Micro asks us if we're ready for six-year-olds coding Arduino boards

Insert Coin: Modkit Micro asks us if we're ready for six-year-olds coding Arduino boards originally appeared on Engadget on Tue, 29 May 2012 10:01:00 EST. Please see our terms for use of feeds.