Compiling and Code Generation using Xcode

Kok Chen, W7AY [w7ay (at) arrl (dot) net]
Last updated: March 12, 2013

Using Xcode with the AVR Tool Chain

Be sure to install the CrossPack AVR tool chain by following the instructions here.

The CrossPack package includes the gcc compiler and library to support the AVR.

If you intend to develop programs with the Mac OS X Xcode IDE, you will need to have installed Xcode. Xcode usually comes as an optional Developer installation on the Mac OS X installation DVD that comes with the Macintosh computer. You can also install the Developer package from the Apple Developer site.

After installation, the Xcode application can be found in the /Developer/Applications folder.


AVR Project Template for Xcode

There are various Xcode templates that you can use with the AVR tool chain to do all of your code development (edit, compile, flagging errors, etc). I have included a set of Xcode templates that blends neatly with AVR Tools.

Currently, the set includes templates for the ATtiny45, ATtiny85, ATmega168, ATmega328p, ATmega32u4, and the ATmega2560.

In pretty much all instances, all you will need to do to create a new Xcode template for a different AVR device is to make a copy of one of the above folders, give the folder the name of the new device (e.g., "ATmega323"), and change the definition for the MCU variable for the Makefile that is present in the template folder:



Or, you can simply tell Xcode to create a new project for the ATmega168 when you start a new project, and then locally editing the above line ("MCU=") in the copy of the Makefile that Xcode generates for your project. You can change the MCU in the makefile at any time to build a hex file for a different processor.

The avr-libc manual has a list of supported AVR devices (MCU).

The set of templates that is provided by AVR Tools assumes that there is a single file called program.c. If your program contains other files, you will need to add other dependencies into the Makefile manually. For example, the following will include a file uart.c as part of your project:



To install this set of Xcode templates, download the disk image from here and then copy the AVR folder from the disk image into the following folder (which should already be on your hard disk):

/Developer/Library/Xcode/Project Templates/

Once the AVR templates are installed into Xcode's Project Template folder, you should see the AVR folder listed under Mac OS X on the left whenever you ask Xcode to create a New Project.



You can simply choose the project template by clicking on the Choose... button.

When you add more templates for other Atmel devices into the AVR template folder, they will appear in the panel on the right of the New Project window.


Building an AVR Project

When you create a new ATtiny85 Project, you should see something like this:



As seen above, a program.c file appears in the project, so does the Makefile.

Note the Make Executable item in the Active Target popup menu at the top left of the project window. This selects the Make Executable target that you can see in the list view below the popup menu. When you click on the Build button (the hammer icon in the Xcode window's shelf), Xcode will execute this target.

If you double click on the Make Executable target (the concentric red circles) itself, you will find that Make Executable simply runs the Makefile ("/usr/bin/make"):



If you double click on the Clean target, you will find this:



Thus, if you were to change the Active Target menu to select Clean, clicking on Build will execute the "clean" objective in the makefile (i.e., "/usr/bin/make clean") . In the Makefile, you will notice that "clean" runs the Unix command "rm -f *.o *.hex *.elf *.map *~", which you can see when you open the Makefile in the Xcode editor:



i.e., if you select Clean as your Active Target and click on the Build button, Xcode will run the Unix command to remove all the files that Make Executable has created.

You can add other targets that you want, adding more entries to the Makefile and save the Project as an Xcode template in the Developer folder. Once you have a usable Xcode template, adding other templates is as easy as making changes and saving the Project and name and use it as a template.