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[on:]

Could someone explain how to do so? Which pins would connect to a ceramic resonator ect?

[Reply #1 on:]

Just look at the datasheet for the TQFP-pinout ATmega640/1280/2560:

10: VCC
11: GND

30: Reset
31: VCC
32: GND
33: XTAL2
34: XTAL1

61: VCC
62: GND

80: VCC
81: GND

98: AREF
99: GND
100: AVCC

[Reply #2 on:]

I'd do it like this.

You can get a breakout board from schmartboards.com, solder the chip in place, then add the few components needed.

[Reply #3 on:]

If you don't like the soldering aspect this guy will do it for you:

http://jkdevices.com/ATMEGA2560

If you do like the soldering aspect, you can get these boards on eBay and do it yourself.  You can probably get the chip from Atmel for free if you can do a little song and dance on the samples request page.

http://www.ebay.com/itm/TQFP-100-TQFP100-0-5mm-pitch-Adapter-PCB-PIC24-PIC32-

[Reply #4 on:]

I am in the process of of designing a custom PCB for the 2560 using Eagle.  I may have an issue though, I have ran the DRC and the Itead DRC check advised that the pins on the 2560 have a clearance issue.  I am probably just going to finish the board and send it too Itead and see if they will still fab it.

[Reply #5 on:]

The '2560 on a breakout board looks like a pretty good deal, but there is only 1 hole/pin.
I like the schmartboard as it gives two holes/pin and I think would make assembling a standalone board a little easier.
I have a couple of 2560 chips & schmartboards, will see if the wife will let me do some playing today.

http://www.schmartboard.com/index.asp?page=products_qfp&id=70

Re: the custom PCB, try this eagle symbol, it has thinned down pads that itead will accept.
The standard one does not have enough clearance between pads for soldermask.
I have used this one before with itead.

[Reply #6 on:]

Thanks Crossroads.  Hate having to rip up all of my traces..  But I guess every designer had to do it at least once..  lol

[Reply #7 on:]

Rip them up because the symbol placement is different?
Can you just drop the new footprint where the old one was, and the let the autorouter take care of the little disconnect at the end?

[Reply #8 on:]

The 2560 I was using had the IO pins and VCC/GND on separate symbols.  The one you gave me was also bigger.  It's ok, I didn't like how I had the traces ran anyway..

[Reply #9 on:]

In the schematic only? The board symbol was okay?
Most of the time, I don't run many traces on the schematic, just names.

[Reply #10 on:]

Yea, the schematic.  The package on the board is the same.  The new symbol you gave me was bigger and had the VCC and GNDs on one symbol so I had to reorganize everything.  I use the naming process to do mine as well.  Just had to line everything up in the schematic.  Like I said before, I didn't like how the traces were coming out on the board so I ripped them up and going to see if I can make it look more professional. 

[Reply #11 on:]

I would start with the Arduino MEGA Schematic and Board files (or maybe the Seeeduino MEGA files) and start deleting the pieces I didn't want.  Possibly just having the board made as-is and partially-populating it rather than doing a new design...

[Reply #12 on:]

What's the fun in that?  I am also here to learn. 

[Reply #13 on:]

I like that style of thinking!

White Christmas for us tomorrow, couple inches of snow on the way ...

[Reply #14 on:]

What's the fun in that?  I am also here to learn. 

You can learn a lot in the process of figuring out someone else's design.
Also, you weren't the original poster...