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1  Development / Suggestions for the Arduino Project / Re: Ethernet shield 3.3V conflict on: January 31, 2011, 03:32:40 pm
You are right RuggedCircuits   smiley  : the file SPI.zip, downloadable from this page

http://www.wiznet.co.kr/Sub_Modules/en/product/product_detail.asp?Refid=99&page=1&cate1=5&cate2=7&cate3=26&pid=1011&cType=2#tab

describes exactly what you said about the w5100 SPI.

Thanks again.

Marco
2  Development / Suggestions for the Arduino Project / Re: Ethernet shield 3.3V conflict on: January 31, 2011, 01:56:02 pm
Thanks for your answer, RuggedCircuits.

Changing subject, by the way can you explain me why in the ethernet shield there is an inverter to enable the SPI interface ony when it is selected, i.e. when SS is low?
In other words, why SEN is not just pullupped?

Thanks in advance.

Marco
3  Development / Suggestions for the Arduino Project / Re: Ethernet shield 3.3V conflict on: January 31, 2011, 11:27:04 am
I appreciate your optimistic view of the issue.

Anyway, do you think there is same reason to adopt a design technique that relies on the values of pcb's tracks resistance? 
4  Development / Suggestions for the Arduino Project / Ethernet shield 3.3V conflict on: January 31, 2011, 06:47:42 am
Hi everybody,

I see in the ethernet shield diagram, http://arduino.cc/en/uploads/Main/arduino-ethernet-shield-05-schematic.pdf, that the 3.3V generated by the on board linear regulator is also connected to the power supply connector.

This cause two voltage regulators (one on the ethernet shield an the other on the cpu board (either Mega or Uno)) to be connected in parallel, and it seems to me this is not a good thing !

Wath do you think?

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