Dear all,
as far as I know, the Ethernet Library does not support the Interrupt.
So on EthernetShield R3 you can enable the /INT signal from W5100 Chip to Pin 2 of Arduino Uno by a solder bridge on the top side, but the Library does not support this.
In a first shot I found a solution to enable the /INT signal coming out of the W5100.
It is not finally tested, but it seems to work in the first
Note: The Interrupt handler has to be programmed separately
void setup ()
{
...
//SPI_Write (IMR,0xFF); // enable all interrupts in w5100
// IMR = Interrupt Mask = 0x0016
//SPI_Write (0x0016,0xFF); // enable all interrupts in w5100
// initialize SPI:
SPI.begin(); // Starte die SPI Library
SPI.setBitOrder(MSBFIRST); // Für W5100 gilt MSB first
digitalWrite(chipSelectPin, LOW); // Set Pin10 to LOW = enable CS for W5100 device
// MSB first, LSB Last
SPI.transfer(0xF0); // opcode 0xF0 = Write Operation // opcode 0x0F = read operation
SPI.transfer(0x00); // Adress field
SPI.transfer(0x16); // Adress field
SPI.transfer(0xFF); // Data field
digitalWrite(chipSelectPin, HIGH); // Set Pin10 to HIGH = disable CS for W5100 device
. . .
} // END of Setup