Arduino
I have just taken possession of one Arduino Uno R3. This is the fancy Make: magazine version so all components are SMD. It has an ATmega328P as its main controller and an ATMega16 to talk to the USB port.
Here's its schematic. https://www.arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf
I have a littleBits kit around too but this is my first genuine Arduino.
Arduino as AVR development board
This board arrived at a convenient time for me, but what I really want to do with it is develop code that can be pushed into my FutureKit Temperature Controller, which is based on an Atmel AVR controller.
Writing programs for Arduino
I know I can use the official Arduino IDE but I also want to know more about [Atmel Studio http://www.atmel.com/tools/atmelstudio.aspx]. Are there advantages for me to use one or the other since I intend to develop for both the Arduino and just plain Atmel AVR controllers.
Atmel Studio
It looks like Atmel Studio is Windows only? How can this be? How sad! Here are instructions to use it on Mac: http://www.thinkcreate.org/index.php/avr-studio-on-mac-os/ There is a toolchain supported for Linux, but no IDE: http://www.atmel.com/tools/ATMELAVRTOOLCHAINFORLINUX.aspx but I am more inclined to try Parallels with Windows 7 first.
Maybe I don't care, if the Arduino IDE works for me. Anyway, I am removing old crud from a W7 machine and that could take several more hours! So, later for Studio.
Arduino IDE
So far it starts up on Mac OS/X, more than I can say for Microchip's MPLAB X!
Arduino has a simple IDE that works. I did indeed write a little program using the Make: Getting Started With Arduino book while sitting at the patio table at California Flora Nursery in Fulton. What a lovely place it is.
Now I wonder if the IDE works with a plain vanilla ATmega328P.
Loading programs into Arduino
Apparently the Arduino model is to put code into EEPROM and then use a bootloader in flash to load it? Where does it get loaded? Flash or RAM?
I am used to working directly with Microchip PIC controllers, programming them with a PicKit3. I find this to be very convenient. Using an ICSP programmer is also possible with Arduino.