Incorporating an Arduino Mega 2560 into finished project?

Hi,

I normally develop my projects using an Arduino Uno and a breadboard or two. For the final project, I use a standalone ATmega328 directly on the project’s PCB. (For example, see here: Arduino - Lithium Battery Load Tester )

My current project is going to need an Arduino Mega 2560 which means I’ll need to incorporate an actual Arduino board onto my PCB.

The PCB will be much larger than the Arduino board so using something based on the “shield” approach isn’t really an option.

My question is what’s the best way to connect lots of individual IO pins from the Arduino mega 2560 board to the main PCB without it becoming a rat’s nest.

The ideal solution would, I think, be if the Arduino mega 2560 had header pins pointing downwards instead of the header sockets pointing upwards but I assume that it doesn’t exist?

Thanks,

John.

vwlowen:
The ideal solution would, I think, be if the Arduino mega 2560 had header pins pointing downwards instead of the header sockets pointing upwards but I assume that it doesn't exist?

Why does the Mega need to be facing upwards? The only parts you may need to see/use is the LED and reset button, both of which can be duplicated on your main board.
Just put pins on your main board at same pitch & spacing as used on a shield and plug the Mega in upside down.

Why don't you just use ribbon cables? I think they are quite "clean"...

Just make a custom board with the Mega2560 chip. SMD soldering isn't as scary as you may think.

Ian.

Thanks for the replies.

I can only make single-sided PCBs using the laser-printer toner etch resist method which isn't really up to such close pin-spacing. And for a PCB without a solder mask, I doubt I'd manage the soldering.

I did think about ribbon cables but part of the circuit involves an SD card with the signal lines passing through a two-way switching IC so it would be useful to keep the wiring as short as possible, I think. But it is something to keep in mind as the project progresses.

It's a shame that one of the inexpensive clone manufacturers doesn't produce a bare breakout board without the headers. It looks like mounting the Arduino mega2560 upside down is going to be the best option.

Thanks again for the suggestions,

John.

vwlowen:
It's a shame that one of the inexpensive clone manufacturers doesn't produce a bare breakout board without the headers. It looks like mounting the Arduino mega2560 upside down is going to be the best option.

Not cheap https://www.sparkfun.com/products/11007
Cheaper but non standard footprint http://www.ebay.co.uk/itm/Mega2560-CORE-mini-2560-Arduino-compatible-3-3V-5V-for-Arduino-mega-2560-/251635670387?pt=LH_DefaultDomain_3&hash=item3a96a79d73

Or something like this.

Ian.

Riva:
Not cheap https://www.sparkfun.com/products/11007
Cheaper but non standard footprint http://www.ebay.co.uk/itm/Mega2560-CORE-mini-2560-Arduino-compatible-3-3V-5V-for-Arduino-mega-2560-/251635670387?pt=LH_DefaultDomain_3&hash=item3a96a79d73

Ah, thanks. The Sparkfun one would be ideal as the single-row headers are easier to do the PCB artwork for but the $:£ exchange rate is about 1:1 which, as you say, makes it expensive.

I might send for the eBay one after the Christmas holiday.

John.

ian332isport:
Or something like this.

http://www.robotshop.com/en/cytron-qfp-breakout-board-100-pins.html

Ian.

Oooo, that one would call my bluff about being able to solder to a breakout board as long as it has solder mask :slight_smile:

John.