24. Gigabit Ethernet MAC (GMAC)

The GMAC module implements a 10/100/1000 MBit/s Ethernet Gigabit MAC compatible with the IEEE 802.3 standard using an address checker, statistics and control registers, receive and transmit blocks, and a DMA interface.

The address checker recognizes four specific 48-bit addresses and contains a 64-bit hash register for matching multicast and unicast addresses. It can recognize the broadcast address of all ones, copy all frames, and act on an external address match signal.

An individual 48-bit MAC address (ETHERNET hardware address) is allocated to each product. This number is stored in flash memory. It is recommended not to change the MAC address in order to comply with IEEE Ethernet standards.

To completely implement ethernet an additional physical layer interface is needed (PHY). Only RGMII is supported on on the StampA5D3x series The GMAC is not present on all variations of the StampA5D3x series. Compare Table 2.1, “SAMA5D3X Device Differences”.