The MAC address of Ethernet Shield

The MAC address of Ethernet Shield(5100&5200)

People ask me question about the MAC address of the Ethernet shield, but the the Ethernet Shield within a 5100&5200 interchip does not have a steady(sole) MAC address. When using the Ethernet shield with Arduino, we need modify the program:

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

Modify the MAC address randomly, you can run the program while the MAC address you input has not been used by other people.
The reason why we can’t provide a sole MAC address to you, just because of the supplier. Sorry for that. And more information you can refer to the specification of Ethernet shield.

Jacket Chen
W5100_Datasheet_v1.2.4.pdf (1.36 MB)