Functional Description
898
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
Ethernet Controller
Table 15-8. Enhanced Receive Descriptor 0 (RDES0) (continued)
Bit
Description
3
RE: Receive Error
When set, this bit indicates that an error occurred during frame reception.
2
DE: Dribble Bit Error
When set, this bit indicates that the received frame has a non-integer multiple of bytes (odd nibbles). This bit is valid
only in MII Mode.
1
CE: CRC Error
When set, this bit indicates that a Cyclic Redundancy Check (CRC) Error occurred on the received frame. This field is
valid only when the Last Descriptor bit (RDES0[8]) is set.
0
Extended Status Available/RX MAC Address
When set, this bit indicates that the extended status is available in descriptor word 4 (RDES4). This is valid only when
the Last Descriptor bit (RDES0[8]) is set. This bit is invalid when Bit 30 is set.
lists the frame information conveyed in bits 7, 5, and 0 of RDES0 when the Checksum Offload
Engine is enabled and disabled through the IPC bit in the EMACCFG register.
Table 15-9. RDES0 Checksum Offload Bits
Bit 5: Frame
Type
Bit 7: IPC
Checksum
Error
Bit 0: Payload
Checksum
Error
IPC Bit Value
in EMACCFG
Register
Frame Status
0
0
0
X
IEEE 802.3 Type frame (Length field value is less than 1536).
This status definition is valid even when the Checksum Offload
engine is disabled.
1
0
0
0
IPv4/IPv6 Type frame in which no checksum error is detected.
1
0
0
1
The frame is an IEEE 802.3 Type frame (Length field value is
greater than or equal to 1536).
1
0
1
1
IPv4/IPv6 Type frame with a payload checksum error detected
1
1
1
1
IPv4/IPv6 Type frame with both IP header and payload
checksum errors detected
0
0
1
1
IPv4/IPv6 Type frame with no IP header checksum error and
the payload check bypassed, due to an unsupported payload
0
1
1
1
A Type frame that is neither IPv4 or IPv6 (the Checksum
Offload engine bypasses checksum completely.)
0
1
0
X
Reserved
Table 15-10. Enhanced Receive Descriptor 1 (RDES1)
Bit
Description
31
Disable Interrupt on Completion
When set, this bit prevents the setting of the Receive Interrupt (RI) bit in the EMACDMARIS register and prevents the
receive interrupt from being asserted.
30:29
Reserved
28:16
RBS2: Receive Buffer 2 Size
These bits indicate the second data buffer size. The buffer size must be a multiple of 4, even if the value of RDES3
(buffer 2 address pointer) is not aligned to the bus width. When the buffer size is not a multiple of 4, the resulting
behavior is undefined. This field is not valid if RCH bit (RDES1[14]) is set.
15
RER: Receive End of Ring
When set, this bit indicates that the descriptor list reached its final descriptor. The DMA returns to the base address of
the list, creating a Descriptor Ring.
14
RCH: Second Address Chained
When set, this bit indicates that the second address in the descriptor is the Next Descriptor address rather than the
second buffer address. When this bit is set, RBS2 (RDES1[28:16]) is a "don't care" value. RDES1[15] takes
precedence over RDES1[14].
13
Reserved