I am working on a project based on Atmega 128 Microcontroller. It is a 64 pin chip, square in shape and has 16 pins on each side.
But when I select it from Atmel's library in Eagle, it comes out rectangular in shape as shown in figure. I do not have any idea for how can I make it exactly as shown in the Figure 2.
The schematic symbol is different than the one used for PCB layout and uses a different image as such (The later being the actual pattern, the symbol being an interpretation). What you need to do is check the pattern, and probably look through all of the Eagle tutorials to get a better idea as to how it all works.
I found these fairly helpful: Cadsoft EagleCad Tutorial Lesson 1 - YouTube
If you want to layout a PCB in eagle you have to create a new project, then a new schematic, then a new board, and click "yes" to making the board track changes to the schematic.
You then add parts in the schematic only, the board will be handled automatically (apart
from arranging the layout)
Many parts in libraries come with a choice of different packages - the schematic symbol
is the same and abstract, the package is the part that goes on the board and is the
physical layout of the solder pads. Always check when selecting a part that you have the
correct package (switch to board window to check if necessary).
Yes - don't want the leadless (-MU) package vs the leaded TQFP (-AU) for example.
If you right click, select Properties, if often has the package info listed.
You can find 2x8 headers in 0.1" spacing under con-lstb library section.