Default MAC Address
When starting an Interface, µC/TCP-IP can automatically use a MAC address either defined in the configuration or already loaded in MAC controller. As specified in Network Interface Configuration each device configuration contains which specify if the MAC address must be load from the MAC, null string, or must load a custom MAC address, string that contain a valid MAC address.
Getting MAC Address
Many types of network interface hardware require the use of a link layer protocol address. In the case of Ethernet, this address is sometimes known as the hardware address or MAC address. In some applications, it may be desirable to get the current configured hardware address for a specific interface. This may be performed by calling NetIF_AddrHW_Get() with the appropriate arguments.
Setting MAC Address
Some applications prefer to configure the hardware device’s hardware address via software during run-time as opposed to a run-time auto-loading EEPROM as is common for many Ethernet devices. If the application is to set or change the hardware address during run-time, this may be performed by calling NetIF_AddrHW_Set() with the appropriate arguments. Alternatively, the hardware address may be statically configured via the device configuration structure and later changed during run-time.
Note: In order to set the hardware address for a particular interface, it must first be stopped. The hardware address may then be set, and the interface re-started.
Getting a Host MAC Address on the Network
In order to determine the MAC address of a host on the network, the Network Protocol Stack must have an ARP cache entry for the specified host protocol address. An application may check to see if an ARP cache entry is present by calling NetARP_CacheGetAddrHW().
If an ARP cache entry is not found, the application may call NetARP_CacheProbeAddrOnNet() to send an ARP request to all hosts on the network. If the target host is present, an ARP reply will be received shortly and the application should wait and then call NetARP_CacheGetAddrHW() to determine if the ARP reply has been entered into the ARP cache.
The following example shows how to obtain the Ethernet MAC address of a host on the local area network: