How to start using AvrStudio, C code and Arduino

Hello to everybody, here you will encounter a simple introduction on how to make the jump from the arduino IDE to plain simple C code with no extra grease(from all those libs made by god know who).
First we will install AvrStudio, which is the official IDE from Atmel(the maker of the micro-controllers used in the arduinos), you can do the download right here:
http://www.atmel.com/dyn/products/tools_card.asp?tool_id=2725
Then just scroll down until you see this line:
AVR Studio 4.18 (build 684) (116 MB, updated 11/09)
Thats the name of the IDE installer, you will need to register to be able to download but its fast and easy and its only a minor thing, then I recommend installing the SP3:
AVR Studio 4.18 SP3 (b716) (31 MB, updated 9/10)
And finally you will need to download the WinAvr that contains the C compiler that will be integrated into the AvrStudio.
http://sourceforge.net/projects/winavr/files/WinAVR/20100110/WinAVR-20100110-install.exe/download

After having downloaded the 3 files you can start installing then, first the AvrStudio file, the the AvrStudio SP3 file and finally the WinAvr, I recommend you to not change any install folder of any of this 3 installers or you may have problems with the compiler not being able to find some files.
And you are ready to enter the great world of embedded C programming.
If you want to follow this tutorial series without changing anything in your system I recommend you to create a folder called AVR in your root directory in C:/ or D:/, in my case I created it in C:/.

You can now start your AvrStudio, you should see this image:

After that you can click in “New Project” and the IDE should show you this window:

As you can see I already filled some of the text boxes and you should copy what I have done in  you window, as you can state the “Project Name” is blinky, tha famous hello world of the micro-controllers, its simple but its great to learn how to use the IDE and how to upload code using the avrdude, as you can also see, the “Initial File” is filled with the same text that the “Project Name” text box has inside, you should also enable the “Create initial file” and “Create folder”, this way the AvrStudio will create one folder for each new project that you create and will also create all the needed files inside that folder.
As we want to programm in C, you need to select the “AVR GCC” line in the “Project type” zone, and don’t forget to change the “Location” to your C:/AVR/ folder.
Now click “Next >>”, this will present you a new window:

As you can see in the image you should select “AVR Simulator 2 ” as the Debug platform and select the “Atmega328p” as your “Device”, because this is the chip present in the Arduino Duemilanove/Uno, after selecting this click in finish and the AvrStudio should present you with your fresh new and empty project ready to get some code in it:

Now we can just start writing down our code, but first lets do it using pseudo-code:

Infinite loop
Turn led on
wait 500ms
turn led off
wait 500ms

Pretty simple hey?
Now lets start to turn this into real code.

#include <avr/io.h>    //This contains definitions for all the registers locations and some other things, must always be included
#define F_CPU 16000000UL    //F_CPU tells the compiler that our crystal is an 16Mhz one so it can generate an accurate delay, must be declared above delay so delay knows what is the value of F_CPU
#include <util/delay.h>        //Contains some delay functions that will generate accurate delays of ms and us

int main(void){            //In ANSI C, the main function as always an int return and using void will give you an warning
while(1){            //This gives us an infinite loop, there should always be an infinite loop in your code, because micro-controllers cant return from main to anywhere and that will give you bad results and unpredicted behaviour
PORTB |= (1<<PB5);    //Turn led on, this is the led included in the arduino(digital pin 13)
_delay_ms(1000);    //Wait 1 second
PORTB &= ~(1<<PB5);        //Turn led off
_delay_ms(1000);    //Wait another second
}
return 1;
}

You can see in this image how to map the pins nomenclature used by arduino to real port names/values using this image:

There is yet one thing to do, can you see what’s missing in the code?
Well, we need to tell to our avr if the pin is an output or an input, using direct port access and the like, this is done using DDRx, where x is the port name(A,B,C or more if you have avr’s with many legs), in our case and as seen above we are using PORTB pin number 5, so the code will be:

DDRB |= (1<<PB5);

And our final code will be something just like this:

#include <avr/io.h>    //This contains definitions for all the registers locations and some other things, must always be included
#define F_CPU 16000000UL    //F_CPU tells the compiler that our crystal is an 16Mhz one so it can generate an accurate delay, must be declared above delay so delay knows what is the value of F_CPU
#include <util/delay.h>        //Contains some delay functions that will generate accurate delays of ms and us

int main(void){            //In ANSI C, the main function as always an int return and using void will give you an warning
DDRB |= (1<<PB5);        //Define digital pin13/PORTB5 as an output so we can blink our led
while(1){            //This gives us an infinite loop, there should always be an infinite loop in your code, because micro-controllers cant return from main to anywhere and that will give you bad results and unpredicted behaviour
PORTB |= (1<<PB5);    //Turn led on, this is the led included in the arduino(digital pin 13)
_delay_ms(1000);    //Wait 1 second
PORTB &= ~(1<<PB5);        //Turn led off
_delay_ms(1000);    //Wait another second
}
return 1;
}

Now you can just type in or copy and paste this code inside the AvrStudio text editor and press F7 that is the button that compiles/builds your code, this should compile without any error or warning, and as you can see in the bottom of the IDE this blinky only uses 172bytes of Flash memory, a lot less than the blinky generated by the arduino IDE.

My next tutorial will be about bitwise operators, so the |=, &=, << and other operators will soon be explained in great detail as they are very handy when you are making some embedded programming.

Now, lets upload our code, but how, there is no button that does this like the Arduino IDE does it, well you will need to use the command line and the avrdude program that is also present in the arduino IDE but its disguised.
To open you command line, and if you are using windows Vista or 7, just type Run in your Start bar, just like this(my images are in Portuguese):

Then in the Run window type “cmd” and press “Enter”/click “Ok”:

And there it is, the Command Line in all its glory:

Now, if you have created your AVR folder in the C:/ just like I advised type the following in your Command Line:

cd /
And press "Enter".
cd AVR
And press "Enter".
cd blinky
And press "Enter".
cd default
And press "Enter".

I know that you have not created the default folder, but this is an folder that is created by the AvrStudio when you compile/build your project and this is where the .hex file is located, this is done for all your projects and is always called default.
Using your Arduino IDE check what is your COM port as you will need that to use the avrdude to upload your .hex file to the arduino.
The generic command to upload code to your arduino using avrdude is this one:

avrdude -p m328p -c avrisp -P com* -b 57600 -F -U flash:w:your_hex_file.hex

In my case the com is com5 and the .hex file is called blinky.hex because the hex file that is generated as always the same name of the project, but if you are unsure just type:

dir

And press “Enter” in the command line and this will show what files are in the default folder.

If you are using an arduino that is not the duemilanove, but maybe the uno, the baud rate(-b 57600) is wrong, the same goes if you use an arduino mega the -p m328p that says what type of Avr is in the board is wrong to, but if you need help send me an email or just leave a comment.
So, to upload our fresh code type this(remember that your com port may be other than 5), and that avrdude is case sensitive, so if it throws you an error check your writing.
So the command line to upload the file in this case is:

avrdude -p m328p -c avrisp -P com5 -b 57600 -F -U flash:w:Blinky.hex

Now, when you press enter to upload your code you need to press the reset button in your Arduino because this simple command line will not activate the auto-reset feature, if you don’t press the reset button in time you will get an “Out of sync” error, but relax and just try again, you don’t need to be very fast, 1-2 seconds of delay between pushing “Enter” and pressing the reset button works fine for me and I never got an “Out of sync” error, if your upload is accomplished with success you should see this:

Now you can watch your Arduino blinking its led with a lot less code inside it and with an happy felling that you are now one step closer to be a better programmer and how things really work inside your arduino, and if you spot any error don’t hesitate about reporting it.
There will a series of tutorials covering all the common things used with an arduino: ADC, timers, interrupts, Serial comms, I2C, SPI, using flash to store big amounts of data, and some projects made by myself to show you even more things, stay tuned.