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Topic: Suggestions about Mega-equivalent with built-in Ethernet (Read 5 times) previous topic - next topic

Jonathan Oxer

I'm just about to go to production with a Mega version of the EtherTen (http://www.freetronics.com/etherten), but it's not too late to make last-minute changes so I'd be very interested in any suggestions. It does everything the EtherTen does (including Power-over-Ethernet, microSD slot, etc) but with more I/O and an ATmega2560 MCU. It also has a small prototyping area which should be handy for single-board sensor / control projects, and I've specifically broken out the I2C connections next to the proto area.

There are still a couple of airwires and some minor pushing and shoving to do, but it's getting quite close:

Obviously it still needs header labels etc sorted out.

Yes, the microSD slot is in a very strange location (right in the middle of the board) but I couldn't figure anywhere better to put it. The Mega has headers and other connectors all the way around the perimeter, so there's just nowhere to put it that overlaps an edge. Hopefully it won't be too much of a pain.

So, any wishlist items or suggestions before I crank out the Gerbers and start production?
Jonathan Oxer
Practical Arduino: www.practicalarduino.com


captain-slow.dk | non contagious!

Jonathan Oxer

shouldn't that be 7-20V?

No, that's deliberate. The combo of the pair of MCUs and the Wiznet Ethernet chipset draws a significant amount of current, and supplying anything more than about 12V to the onboard linear regulator can push it closer to the thermal limit than I like: particularly if you stack another shield on top that draws lots of current, such as an LCD shield with a backlight. A combination of boards like an Uno with an Arduino Ethernet Shield and an LCD shield has the same problem. If you feed it 10V it'll be quite happy. At 12V the reg gets very warm, and at 20V it would almost certainly go into thermal shutdown.

You *can* feed it more, but the 7-10V range indicated on the overlay is a recommendation that gives a bit of a safety margin.


Why not connecting it with the external memory bus?
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Dito isto, mensagens pessoais só se forem pessoais, ou seja, se já interagimos de alguma forma no passado ou se me pretendes convidar para uma churrascada com cerveja (paga por ti, obviamente).


Nice routing, Jon!  I'm sure that was a ton of work.

I might be totally wrong about this, but I have seen PCBs with a vRestrict area under crystals because a via under a crystal will be in contact with the crystal's metal case.  There is a via under one of your crystals (connected to GND I believe?).  Just thought I'd mention it in case it was not intentional.

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