SAM3X8E Atmel Corporation, SAM3X8E Datasheet - Page 1276

• Manufacturer Part Number: SAM3X8E
• Manufacturer: Atmel Corporation

41.4.10
41.4.11
41.4.12
1276
1276
SAM3X/A
SAM3X/A
Type ID Checking
VLAN Support
PHY Maintenance
rx_er asserted during reception are discarded and all others are received. Frames with FCS
errors are copied to memory if bit 19 in the network configuration register is set.
The contents of the type_id register are compared against the length/type ID of received frames
(i.e., bytes 13 and 14). Bit 22 in the receive buffer descriptor status is set if there is a match. The
reset state of this register is zero which is unlikely to match the length/type ID of any valid Ether-
net frame.
Note:
An Ethernet encoded 802.1Q VLAN tag looks like this:
Table 41-4.
The VLAN tag is inserted at the 13
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:
The register EMAC_MAN enables the EMAC to communicate with a PHY by means of the MDIO
interface. It is used during auto-negotiation to ensure that the EMAC and the PHY are config-
ured for the
The PHY maintenance register is implemented as a shift register. Writing to the register starts a
shift operation which is signalled as complete when bit two is set in the network status register
(about 2000 MCK cycles later when bit ten is set to zero, and bit eleven is set to one in the net-
work configuration register). An interrupt is generated as this bit is set. During this time, the MSB
of the register is output on the MDIO pin and the LSB updated from the MDIO pin with each
MDC cycle. This causes transmission of a PHY management frame on MDIO.
Reading during the shift operation returns the current contents of the shift register. At the end of
management operation, the bits have shifted back to their original locations. For a read opera-
tion, the data bits are updated with data read from the PHY. It is important to write the correct
values to the register to ensure a valid PHY management frame is produced.
The MDIO interface can read IEEE 802.3 clause 45 PHYs as well as clause 22 PHYs. To read
clause 45 PHYs, bits[31:28] should be written as 0x0011. For a description of MDC generation,
see the network configuration register in the
• 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
• Bit 19, 18 and 17 set to priority if bit 21 is set
• Bit 16 set to CFI if bit 21 is set
TPID (Tag Protocol Identifier) 16 bits
set bit 21 is set also.)
A type ID match does not affect whether a frame is copied to memory.
same speed and duplex configuration.
802.1Q VLAN Tag
0x8100
th
byte of the frame, adding an extra four bytes to the frame. If
First 3 bits priority, then CFI bit, last 12 bits VID
“Network Control Register” on page
TCI (Tag Control Information) 16 bits
11057A–ATARM–17-Feb-12
11057A–ATARM–17-Feb-12
1283.