K60P100M100SF2RM Datasheet, PDF (1217/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Chapter 44 10/100-Mbps Ethernet MAC (ENET)
Table 44-85. Receive Buffer Descriptor Field Definitions (continued)
Word
Offset + A
Field
15–6
Description
Reserved, must be cleared.
Offset + A
5
IP header checksum error. This is an accelerator option. This bit is written by the
ICE
uDMA. Set when either a non-IP frame is received or the IP header checksum
was invalid. An IP frame with less than 3 bytes of payload is considered to be an
invalid IP frame. This bit is only valid if the L bit is set.
Offset + A
4
PCR
Protocol checksum error. This is an accelerator option. This bit is written by the
uDMA. Set when the checksum of the protocol is invalid or an unknown protocol
is found and checksumming could not be performed. This bit is only valid if the L
bit is set.
Offset + A
3
Reserved, must be cleared.
Offset + A
Offset + A
2
VLAN
1
IPV6
VLAN. This is an accelerator option. This bit is written by the uDMA. This bit
means that the frame has a VLAN tag. This bit is valid only if the L bit is set.
IPV6 Frame. This bit is written by the uDMA. This bit indicates that the frame
has a IPv6 frame type. If this bit is not set it means that an IPv4 or other protocol
frame was received. This bit is valid only if the L bit is set.
Offset + A
0
FRAG
IPv4 Fragment.This is an accelerator option.This bit is written by the uDMA.This
bit indicates that the frame is an IPv4 fragment frame. This bit is only valid when
the L bit is set.
Offset + C
15–11
Header length
Header length. This is an accelerator option. This field is written by the uDMA.
This field is the sum of 32 bit words found within the IP and its following protocol
headers. If an IP datagram with an unknown protocol is found the value is the
length of the IP header. If no IP frame or an erroneous IP header is found, the
value is 0. The following values are minimum values if no header options exist in
the respective headers:
• ICMP/IP: 6 (5 IP header, 1 ICMP header)
• UDP/IP: 7 (5 IP header, 2 UDP header)
• TCP/IP: 10 (5 IP header, 5 TCP header)
Offset + C
Offset + C
Offset + E
Offset + 10
Offset + 10
Offset + 12
Offset + 14
Offset + 16
This field is only valid if the L bit is set.
10–8
Reserved, must be cleared.
7–0
Protocol type
Protocol type. This is an accelerator option. The 8-bit protocol field found within
the IP header of the frame. Only valid if ICE is cleared. This bit is only valid if the
L bit is set.
15–0
Payload
checksum
Internet payload checksum. This is an accelerator option. The one's complement
sum of the payload section of the IP frame. The sum is calculated over all data
following the IP header until the end of the IP payload. This field is valid only
when the L bit is set.
15
BDU
Last buffer descriptor update done. Indicates that the last BD data has been
updated by uDMA. This bit is written by the user (=0) and uDMA (=1).
14–0
Reserved, must be cleared.
15–0
Reserved, must be cleared.
15–0
This value is written by the uDMA. It is only valid if the L bit is set.
1588 timestamp
Table continues on the next page...
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
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