I read through several thread and datasheets but I can't understand yet the situation.
I have a Arduino 2009 board and the Ethernet shields (the old version, w/ the large SD footprint).
I know the SD connector is not supported (why place it then?) but I don't understand if I connect an external SD connector to the female connector on the side of the shields. In this case what wires I need?
The goal is to store web pages into the SD card.
Thank you in advance
For data you need three of the SPI pins (D11, D12, and D13) and an unused data pin to act as the Slave Select pin. You also need 3.3v power and Ground. You should provide some voltage dividers between the Arduino's 5V outputs (MOSI, SCK, Slave Select) and the SD card's 3.3V inputs. I've used two 1k resistors in series between the Arduino output and Ground and connected the SD pin to the connection between the resistors. This provides a (roughly) 2.5V logic signal which is plenty for a 3.3V device. The 3.3V output of the SD card (MISO) will work fine with the 5V input of the Arduino.