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AT32F435/437
Series Reference Manual
2022.11.11
Page 599
Rev 2.03
contains the beginning of the frame.
Bit 8
LS
rw
Last descriptor
When set, this bit indicates that the buffers pointed to by this descriptor are the last
buffers of the frame.
Bit 7
IPHCE
rw
IPv header checksum error
When set, this bit indicates an error in the IPv4 or IPv6 header. This error can be
due to mismatched Ethernet type filed and IP version field, IPv4 header checksum
error or an Ethernet frame lacking the desired number of IP header bytes.
Bit 6
LC
rw
Late collision
When set, this bit indicates that a late collision has occurred while receiving the
frame in half-duplex mode.
Bit 5
FT
rw
Frame type
When set, this bit indicates that the received frame is an Ethernet frame (the LT field
is greater than or equal to 1536). When this bit is cleared, it indicates that the
received frame is an IEEE802.3 frame. This bit is invalid when the received frame
is a runt frame shorter than 14 bytes.
Bit 4
RWT
rw
Receive watchdog timeout
When set, this bit indicates the receive watchdog timeout has occurred while
receiving the current frame. The current frame is truncated after the watchdog
timeout.
Bit 3
RE
rw
Receive error
When set, this bit indicates that the RX_ER signal is valid while the RX_DV is valid
during frame reception.
Bit 2
DE
rw
Dribble bit error
When set, this bit indicates that the received frame is not an integer multiple of bytes
(odd nibbles) This bit is valid only in MII mode.
Bit 1
CE
rw
CRC error
When set, this bit indicates a CRC error occurred on the received frame. This bit is
valid only when the LS bit is set.
Bit 0
PCE
rw
Payload checksum error
When set, this bit indicates that the TCP, UDP or ICMP checksum calculated by the
MAC core does not match the received TCP, UDP or ICMP checksum field. This bit
is also set when the received payload size does not match the length filed value of
the IPv4 or IPv6 datagram in the received Ethernet frame.
Table 26-7 shows the definitions of bit 5, 7 and 0.
Table 26-7
Receive descriptor 0
Bit 5:
Frame type
Bit 7:
Checksum
error
Bit 0:
Payload
checksum
error
Frame status
0
0
0
IEEE802.3 type frame (length filed value is less than
0x0600)
1
0
0
IPv4/IPv6 type frame, no checksum error detected
1
0
1
IPv4/IPv6 type frame with payload checksum error
detected (PCE bit)
1
1
0
IPv4/IPv6 type frame with an IP header checksum
error detected (IPC CE bit)
IPv4/IPv6 type frame with both IP header and
payload checksum errors detected
1
1
1
IPv4/IPv6 type frame with no IP header checksum
error detected and the payload check bypassed due
to an unsupported payload
0
0
1
A type frame is neither IPv4 nor IPv6 (the checksum
offload bypasses checksum inspection)
0
1
1
0
1
0
Reserved