Datasheet

...........continued
Bit Function
23:22 This bit has a different meaning depending on whether RX checksum offloading is enabled.
With RX checksum of
floading disabled: (bit 24 clear in Network Configuration)
Type ID register match. Encoded as follows:
00: Type ID register 1 match
01: Type ID register 2 match
10: Type ID register 3 match
11: Type ID register 4 match
If more than one Type ID is matched only one is indicated with priority 4 down to 1.
With RX checksum offloading enabled: (bit 24 set in Network Configuration Register)
00: Neither the IP header checksum nor the TCP/UDP checksum was checked.
01: The IP header checksum was checked and was correct. Neither the TCP nor UDP checksum was
checked.
10: Both the IP header and TCP checksum were checked and were correct.
11: Both the IP header and UDP checksum were checked and were correct.
21 VLAN tag detected—type ID of 0x8100. For packets incorporating the stacked VLAN processing feature, this
bit will be set if the second VLAN tag has a type ID of 0x8100
20 Priority tag detected—type ID of 0x8100 and null VLAN identifier. For packets incorporating the stacked
VLAN processing feature, this bit will be set if the second VLAN tag has a type ID of 0x8100 and a null
VLAN identifier.
19:17 VLAN priority—only valid if bit 21 is set.
16 Canonical format indicator (CFI) bit (only valid if bit 21 is set).
15 End of frame—when set the buffer contains the end of a frame. If end of frame is not set, then the only valid
status bit is start of frame (bit 14).
14 Start of frame—when set the buffer contains the start of a frame. If both bits 15 and 14 are set, the buffer
contains a whole frame.
13 This bit has a different meaning depending on whether jumbo frames and ignore FCS modes are enabled. If
neither mode is enabled this bit will be zero.
With jumbo frame mode enabled: (bit 3 set in Network Configuration Register) Additional bit for length of
frame (bit[13]), that is concatenated with bits[12:0]
With ignore FCS mode enabled and jumbo frames disabled: (bit 26 set in Network Configuration Register
and bit 3 clear in Network Configuration Register) This indicates per frame FCS status as follows:
0: Frame had good FCS
1: Frame had bad FCS, but was copied to memory as ignore FCS enabled.
12:0 These bits represent the length of the received frame which may or may not include FCS depending on
whether FCS discard mode is enabled.
With FCS discard mode disabled: (bit 17 clear in Network Configuration Register)
Least significant 12 bits for length of frame including FCS. If jumbo frames are enabled, these 12 bits are
concatenated with bit[13] of the descriptor above.
With FCS discard mode enabled: (bit 17 set in Network Configuration Register)
Least significant 12 bits for length of frame excluding FCS. If jumbo frames are enabled, these 12 bits are
concatenated with bit[13] of the descriptor above.
SAM E70/S70/V70/V71 Family
GMAC - Ethernet MAC
© 2019 Microchip T
echnology Inc.
Datasheet
DS60001527D-page 578