Functional Description
900
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Ethernet Controller
Table 15-13. Enhanced Received Descriptor 4 (RDES4) (continued)
Bit
Description
11:8
Message Type
These bits are encoded to give the type of the message received:
• 0x0 = No PTP message received
• 0x1 = SYNC (all clock types)
• 0x2 = Follow_Up (all clock types)
• 0x3 = Delay_Req (all clock types)
• 0x4 = Delay_Resp (all clock types)
• 0x5 = Pdelay_Req (in peer-to-peer transparent clock)
• 0x6 = Pdelay_Resp (in peer-to-peer transparent clock)
• 0x7 = Pdelay_Resp_Follow_Up (in peer-to-peer transparent clock)
• 0x8 = Announce
• 0x9 = Management
• 0xA = Signaling
• 0xB to 0xE = Reserved
• 0xF = PTP packet with Reserved message type
7
IPv6 Packet Received
When set, this bit indicates that the received packet is an IPv6 packet. This bit is updated only when the IPC bit of the
EMACCFG register is set.
6
IPv4 Packet Received
When set, this bit indicates that the received packet is an IPv4 packet. This bit is updated only when the IPC bit of the
EMACCFG register is set.
5
IP Checksum Bypassed
When set, this bit indicates that the checksum offload engine is bypassed.
4
IP Payload Error
When set, this bit indicates that the 16-bit IP payload checksum (that is, the TCP, UDP, or ICMP checksum) that the
core calculated does not match the corresponding checksum field in the received segment. It is also set when the TCP,
UDP, or ICMP segment length does not match the payload length value in the IP Header field. This bit is valid when
either Bit 7 or Bit 6 is set.
3
IP Header Error
When set, this bit indicates that either the 16-bit IPv4 header checksum calculated by the core does not match the
received checksum bytes, or the IP datagram version is not consistent with the Ethernet Type value. This bit is valid
when either Bit 7 or Bit 6 is set.
2:0
IP Payload Type
These bits indicate the type of payload encapsulated in the IP datagram processed by the Receive Checksum Offload
Engine (COE). The COE sets this field to 0x0 if it does not process the IP datagram's payload due to an IP header
error or fragmented IP packet.
• 0x0 = Unknown or did not process IP payload
• 0x1 = UDP
• 0x2 = TCP
• 0x3 = ICMP
• 0x4 to 0x7 = Reserved
This bit is valid when either Bit 7 or Bit 6 is set.
Table 15-14. Enhanced Receive Descriptor 6 (RDES6)
Bit
Description
31:0
RTSL: Receive Frame Timestamp Low
This field is updated by the DMA with the least significant 32 bits of the timestamp captured for the corresponding
receive frame. This field is updated by the DMA only for the last descriptor of the receive frame which is indicated by
Last Descriptor status bit (RDES0[8]).