swordfishBob:
[quote author=Jonathan Oxer link=topic=67714.msg498419#msg498419 date=1311804407]
@bubulindo:Why not connecting it with the external memory bus?
I don't understand. What external memory bus? Care to elaborate?
Guessing he means connect the ethernet feature via address/data port A (D22-29) with D39 ALE, D40 Rd, D41 Wr, rather than using the SPI port. I don't know if there's any existing Arduino ethernet kits that do this. Using SPI means compatibility with existing ethernet shields and EtherTen.
Or have I misunderstood what bubulindo was suggesting?
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Yes, that was exactly it. Plus an interrupt connection from the W5100 to the ATmega so you wouldn't have to poll the chip to know if someone was connected there. The reason for that is that with a big memory chip like the 1280 or 2560, there is a lot more space to put in a webpage and act as a server and not a client. Although I believe that this is also in the Ethernet shields so should be here too.
Although the current library wouldn't work, I remember seeing the application note from Wiznet and the code they had (which is used in the library) was prepared to handle both interface situations.
This would add bulk to the board as you would need a latch and a lot more vias going around, so you wouldn't have such a compact PCB as you do now.
Also, have a look and see if it's possible to place two connections on the TOSC pins in the chip. That way you could place a 32,768kHz crystal and run a clock in software on the board. Since this is most likely to be used connected to the internet at almost all times, you wouldn't need an external RTC and just have a crystal to keep time and synchronize time from the internet.