Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Data Sheet

 735

SAM9M10 [DATASHEET]

6355F–ATARM–12-Mar-13

An Ethernet encoded 802.1Q VLAN tag looks like this:

The VLAN tag is inserted at the 13

th

 

byte of the frame, adding an extra four bytes to the frame. If the VID (VLAN

identifier) is null (0x000), this indicates a priority-tagged frame. The MAC can support frame lengths up to 1536
bytes, 18 bytes more than the original Ethernet maximum frame length of 1518 bytes. This is achieved by setting
bit 8 in the network configuration register.

The following bits in the receive buffer descriptor status word give information about VLAN tagged frames:

• Bit 21 set if receive frame is VLAN tagged (i.e. type id of 0x8100)

• Bit 20 set if receive frame is priority tagged (i.e. type id of 0x8100 and null VID). (If bit 20 is set bit 21 is set also.)

• Bit 19, 18 and 17 set to priority if bit 21 is set

• Bit 16 set to CFI if bit 21 is set

The receive block supports Wake-on-LAN by detecting the following events on incoming receive frames:

• Magic packet

• ARP request to the device IP address

• Specific address 1 filter match

• Multicast hash filter match

If one of these events occurs Wake-on-LAN detection is indicated by asserting the 

wol

output pin for 64 

rx_clk

cycles. These events can be individually enabled through bits[19:16] of the Wake-on-LAN register. Also, for Wake-
on-LAN detection to occur, receive enable must be set in the network control register, however a receive buffer
does not have to be available. 

wol

assertion due to ARP request, specific address 1 or multicast filter events

occurs even if the frame is errored. For magic packet events, the frame must be correctly formed and error free.

A magic packet event is detected if all of the following are true:

• magic packet events are enabled through bit 16 of the Wake-on-LAN register

• the frame’s destination address matches specific address 1

• the frame is correctly formed with no errors

• the frame contains at least 6 bytes of 0xFF for synchronization

•

there are 16 repetitions of the contents of specific address 1 register immediately 

following the synchronization

An ARP request event is detected if all of the following are true:

• ARP request events are enabled through bit 17 of the Wake-on-LAN register

• broadcasts are allowed by bit 5 in the network configuration register

• the frame has a broadcast destination address (bytes 1 to 6)

• the frame has a type ID field of 0x0806 (bytes 13 and 14)

• the frame has an ARP operation field of 0x0001 (bytes 21 and 22)

•

the least significant 16 bits of the frame’s ARP target protocol address (bytes 41 

and 42) match the value 

programmed in bits[15:0] of the Wake-on-LAN register

802.1Q VLAN Tag 

0x8100

First 3 bits priority, then CFI bit, last 12 bits VID