I am new to Arduino and just purchased my first two boards. The boards are both Arduino Uno R3, where on of them is with a standard microcontroller with leaded pins and the other board is with a SMD type micro.
When I ordered the boards one of them was mentioned with the text "with long pin's". I didn't pay to close attention to this at the time of ordering.
I also bought an ethernet shield and now I suddently see some differences. The UNO R3 with the long pins doesn't have the standart ICSP connector to interface with the ethernet shield. On this board the ICSP connector faces downward from the solder side of the board.
What is the purpose of having this ICSP connector facing downwards?
As they are both UNO R3 boards I anticipated that they where compatible. I have googled various sited but can't find an answer to this yet.
So you can put a shield onto the board and still use the ISP headers even when the shield covers it up on the top, I think. Most shields don't actually use the ISP header, but instead, if they connect to it, just act as pass-through. Does the ethernet shield actually need those pins? I'd be surprised if it did.
DrAzzy:
Does the ethernet shield actually need those pins? I'd be surprised if it did.
It does, because it's the only way to connect to the SPI interface on the UNO, MEGA, and Leonardo with one set of pins. On the UNO those pins are connected to Pins 11-13. On the MEGA they are connected to Pins 51-53, and on the Leonardo they are the only pins connected to the SPI interface.
The "long pin" UNO R3 is an official Arduino, part number A000099 (the 'normal' UNO R3 is A000066). It seems to be available from various european distributors: Farnell.com, TME.eu, Amazon.co.uk, uk.rs-online.com, etc. It makes sense to use long pins if you want to put the UNO on top of a shield but in most cases it doesn't make sense to put the ICSP pins on the bottom.
You COULD put the Ethernet Shield on the bottom of a Long Pin UNO if you moved the ICSP connector socket from the bottom of the Ethernet Shield to the top (assuming the pins are long enough).
I believe that the ethernet shield makes use of the ICSP connector. At least I couldn't get it to work with the UNO long pin version, but with the same code it worked flawless on my other "standard" UNO. That's why I guess the ICSP connection to the ethernet shield makes the difference.
JSDK:
I believe that the ethernet shield makes use of the ICSP connector.
Yes, it does. That is why you would have to put the ICSP socket on the TOP of the Ethernet Shield if you wanted to use it on the bottom of a long-pin UNO.