Cypress S6J3200 Series, Manual

Page: 588 / 1355

CHAPTER 21:Ethernet MAC
S6J3200 Series Hardware Manual Document Number: 002-04852 Rev. *G 587
Bit Function
27
Transmit frame corruption due to AXI error - set if an error occurs whilst midway through reading
through reading transmit frame from the AXI, including RRESP/BRESP errors and buffers
exhausted mid frame (if the buffers run out during transmission of a frame then transmission
stops, FCS shall be bad and
TX_ER
asserted). Also set if single frame is too large for the
transmit packet buffer memory size.
26 Transmit error detected.
25:24 Reserved
23
For Extended Buffer Descriptor Mode this bit indicates a timestamp has been captured in the
BD. Otherwise unused.
22:20
Transmit IP/TCP/UDP checksum generation offload errors:
000 - No error
001 - The Packet was identified as a VLAN type, but the header was not fully complete, or had
an
error in it.
010 - The Packet was identified as a SNAP type, but the header was not fully complete, or had
an
error in it.
011 - The Packet was not of an IP type, or the IP packet was invalidly short, or the IP was not
of
type IPv4/IPv6
100 - The Packet was not identified as VLAN, SNAP or IP.
101 - Non supported packet fragmentation occurred. For IPv4 packets, the IP checksum was
generated and inserted.
110 - Packet type detected was not TCP or UDP, TCP/UDP checksum was therefore not
generated. For IPv4 packets, the IP checksum was generated and inserted.
111 - A premature end of packet was detected and the TCP/UDP checksum could not be
generated.
19:17 Reserved
16
No CRC to be appended by MAC. When set this implies that the data in the buffers already
contains a valid CRC and hence no CRC or padding is to be appended to the current frame by
the MAC.
This control bit must be set for the first buffer in a frame and will be ignored for the subsequent
buffers of a frame.
Note that this bit must be “0” when using the transmit IP/TCP/UDP checksum generation offload,
otherwise checksum generation and substitution will not occur.
Note this bit must also be “0” when TX Partial Store and Forward mode is active.
15 Last buffer, when “1” this bit will indicate the last buffer in the current frame has been reached.
14 Reserved
13:0 Length of buffer.
When Descriptor Timestamp Capture mode is enabled, the following table identifies the added descriptor
words.
Bit Function
Word 2
31:30 Timestamp seconds [1:0] (see Note1)
29:0 Timestamp nanoseconds [29:0] (see Note1)