Arduino library that reads stores network settings to EEPROM. This is useful to associate a network configuration with a specific Arduino board which can then be read by many sketches without having to be set in each sketch.

This library stores to EEPROM:

• the MAC address of the interface
• whether DHCP should be used to configure IP settings
• if DHCP is not used, then the manual IP settings for the interface

The library also contains a function to configure the Ethernet adapter from the configuration stored in EEPROM. If network configuration has not been stored in EEPROM then the following configuration will apply:

• A random MAC address in the form DE:AD:BE:EF:xx:xx (where xx is a random number between 0 and 255) will be generated and stored in EEPROM.
• The IP address will be configured using DHCP, and this configuration will be stored in EEPROM

To use the the NetEEPROM library the sketch will need to contain the following includes:

#include <EEPROM.h>
#include <SPI.h>
#include <Ethernet.h>
#include <NetEEPROM.h>

To set a MAC address with DHCP configuration, use the following code:

byte mac[6] = { 0xCA, 0xFE, 0xBA, 0xBE, 0x00, 0x00 };
NetEeprom.writeDhcpConfig(mac);

To set a MAC address with manual IP configuration, use the following code:

byte mac[6] = { 0xCA, 0xFE, 0xBA, 0xBE, 0x00, 0x00 };
byte ip[4] = { 192, 168, 1, 100 };
byte dns[4] = { 8, 8, 8, 8 };
byte gw[4] = { 192, 168, 1, 1 };
byte subnet[4] = { 255, 255, 255, 0 };
NetEeprom.writeManualConfig(mac, ip, dns, gw, subnet);

To set up the Ethernet adapter with configuration from EEPROM, use the following line:

NetEeprom.begin();

If you wish to configure the start address in EEPROM where the network configuration resides, call the setEepromOffset() following method before calling any other methods. If you do not call this method, then the default EEPROM location set set to 0. To set the network configuration at a custom EEPROM offset, use the following code.

NetEeprom.setEepromOffet(128);
byte mac[6] = { 0xCA, 0xFE, 0xBA, 0xBE, 0x00, 0x00 };
NetEeprom.writeDhcpConfig(mac);

To read network configuration at a custom EEPROM offset, use the following code:

NetEeprom.setEepromOffset(128);
NetEeprom.begin();