Does shield stacking order matter?

[SunnyBoy]

Hello everyone,

I have a project with an arduino UNO, a proto shield with some electronics on it and the official ethernet shield.

The ethernet functions work only when the ethernet shield is directly stacked on top of the arduino. When the protoshield is stacked between the arduino and the ethernet shield, I can't connect it to ethernet, I can't ping, I cant post data... nada!

Can someone explain to me why it is like this?

Thanks

[robtillaart]

The new ethershield (think version 5) needs to be on top because of the ICSP  header needs to be connected to the ethershield.

If you are using an older shield, there might be an unintended shortcut due to some components on the middle shield,

[SunnyBoy]

The new ethershield (think version 5) needs to be on top because of the ICSP  header needs to be connected to the ethershield.

If you are using an older shield, there might be an unintended shortcut due to some components on the middle shield,

Thanks... that's probably it. But why does the ethernet shield need to be connected to the ICSP ?

[robtillaart]

Thanks... that's probably it. But why does the ethernet shield need to be connected to the ICSP ?

Check the schematics - http://arduino.cc/en/uploads/Main/arduino-ethernet-shield-05-schematic.pdf - and you see the ICSP header on the right.
The names MISO MOSI and SCK indicate the SPI bus, which is used by both Ethernetchip and the SD card.

Rob

[SunnyBoy]

Thanks... that's probably it. But why does the ethernet shield need to be connected to the ICSP ?

Check the schematics - http://arduino.cc/en/uploads/Main/arduino-ethernet-shield-05-schematic.pdf - and you see the ICSP header on the right.
The names MISO MOSI and SCK indicate the SPI bus, which is used by both Ethernetchip and the SD card.

Rob

I see... this is strange because usually SPI pins are D11, D12,D13 plus D10 for selection.
Anyway, thanks a lot Rob.

[robtillaart]

That are the pins on the Arduino board, but are they also teh pins on the ethershield ?  I have none around to look...., sorry ..

[SunnyBoy]

Yes, on the ethernet shield the D 10,11,12,13 are marked as used.
It is something really strange.

[fafabio]

Hello all,

I have a problem with this too. I got an Mega with and ethershield that uses the 10-13 pins, but also the ICSP header.

can someone explain me this? what is the really useful pins? the header on the right ( with the 6 pins) or the 10-13 pins? or, in my case, on the MEGA, should I use the 10-13 or the 50-53 or even the 50-52 and leave the 10 put?

this is driving me nuts, because I cannot figure out how have worked in the past and is sort of random...