Used to configure the CS (chip select) pin for the Ethernet controller chip. The Ethernet library has a default CS pin, which is usually correct, but with some non-standard Ethernet hardware you might need to use a different CS pin.
Ethernet.init(sspin)
Nothing
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
IPAddress ip(10, 0, 0, 177);
void setup() {
Ethernet.init(53); // use pin 53 for Ethernet CS
Ethernet.begin(mac, ip);
}
void loop () {}