SPRUII0F May 2019 – June 2024 TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S
This format is applicable only to the last descriptor of a packet.
31 | 30 | 29 | 28 | 27:24/22:18 | 23 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7:4 | 3 | 2 | 1 | 0 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
OWN | CTXT | FD | LD | Rsvd | DE | TTSS | EUE | ES | JT | FF | PCE | LoC | NC | LC | EC | CC | ED | UF | DB | IHE |
Bit | Name | Description |
---|---|---|
31 | OWN | Own Bit |
When this bit is set, the bit indicates that the Ethernet module DMA owns the descriptor. The DMA clears this bit when the DMA completes the packet transmission. After the write-back is complete, this bit is cleared to 0. | ||
30 | CTXT | Context Type |
This bit can be cleared to 0 for Normal descriptor. | ||
29 | FD | First Descriptor |
This bit indicates that the buffer contains the first segment of a packet. | ||
28 | LD | Last Descriptor |
This bit is set 1 for last descriptor of a packet. The DMA writes the status fields only in the last descriptor of the packet. | ||
27-24 | Rsvd | Reserved |
23 | DE | Descriptor Error |
When this bit is set, the bit indicates that the descriptor content is incorrect. The DMA sets this bit during write-back while closing the descriptor. | ||
Descriptor Errors can be: | ||
Note 1: When Descriptor Error occurs due to All 1s or CTXT, LD, and FD bits set to 1, the Transmit DMA closes the transmit descriptor with DE and LD bits set to 1. When IOC bit in TDES2 of corresponding first descriptor is set to 1, Transmit DMA sets the TI bit in the DMA_CH#_Status register | ||
Note 2: Based on CTXT, LD, and FD bits of the transmit descriptor, the subsequent descriptor can be considered as the First Descriptor (even if FD bit is not set) and partial packet is sent. | ||
22-18 | Rsvd | Reserved |
17 | TTSS | Tx Timestamp Status |
This status bit indicates that a timestamp has been captured for the corresponding transmit packet. When this bit is set, TDES0 and TDES1 have timestamp values that were captured for the Transmit packet. This field is valid only when the Last Segment control bit (TDES3[28]) in a descriptor is set. This bit is valid only when IEEE1588 time-stamping feature is enabled; otherwise, the bit is reserved. | ||
16 | EUE | ECC Uncorrectable Error Status |
Indicates the ECC uncorrectable error in the TSO memory. | ||
Note: Uncorrectable error in Transmit FIFO memory is reported with (Bit 13) FF = 1. This is because, all such packets are flushed by Ethernet module. | ||
15 | ES | Error Summary |
This bit indicates the logical OR of the following bits: | ||
TDES3[0]: IP Header Error | ||
TDES3[14]: Jabber Timeout | ||
TDES3[13]: Packet Flush | ||
TDES3[12]: Payload Checksum Error | ||
TDES3[11]: Loss of Carrier | ||
TDES3[10]: No Carrier | ||
TDES3[9]: Late Collision | ||
TDES3[8]: Excessive Collision | ||
TDES3[3]: Excessive Deferral | ||
TDES3[2]: Underflow Error | ||
This bit is also set when EUE (bit 16) is set. | ||
14 | JT | Jabber Timeout |
This bit indicates that the MAC transmitter has experienced a jabber time-out. This bit is set only when the JD bit of the MAC_Configuration register is not set. | ||
13 | FF | Packet Flushed |
This bit indicates that the DMA or MTL flushed the packet because of a software flush command given by the CPU. | ||
12 | PCE | Payload Checksum Error |
This bit indicates that the Checksum Offload engine had a failure and did not insert any checksum into the encapsulated TCP, UDP, or ICMP payload. This failure can be either because of insufficient bytes, as indicated by the Payload Length field of the IP Header or the MTL starting to forward the packet to the MAC transmitter in Store-and-Forward mode without the checksum having been calculated yet. This second error condition only occurs when the Transmit FIFO depth is less than the length of the Ethernet packet being transmitted to avoid deadlock, the MTL starts forwarding the packet when the FIFO is full, even in the store-and-forward mode. | ||
This error can also occur when Bus Error is detected during packet transfer. When the Full Checksum Offload engine is not enabled, this bit is reserved. | ||
11 | LoC | Loss of Carrier |
This bit indicates that Loss of Carrier occurred during packet transmission (that is, the gmii_crs_i signal was inactive for one or more transmit clock periods during packet transmission). This is valid only for the packets transmitted without collision and when the MAC operates in the half-duplex mode. | ||
10 | NC | No Carrier |
This bit indicates that the carrier sense signal form the PHY was not asserted during transmission. | ||
9 | LC | Late Collision |
This bit indicates that packet transmission was aborted because a collision occurred after the collision window (64 byte times including Preamble in MII mode). This bit is not valid if Underflow Error is set. | ||
8 | EC | Excessive Collision |
This bit indicates that the transmission was aborted after 16 successive collisions while attempting to transmit the current packet. If the DR bit is set in the MAC_Configuration register, this bit is set after first collision and the transmission of the packet is aborted. | ||
7-4 | CC | Collision Count |
This 4-bit counter value indicates the number of collisions occurred before the packet was transmitted. The count is not valid when the EC bit is set. | ||
3 | ED | Excessive Deferral |
This bit indicates that the transmission ended because of excessive deferral of over 24,288 bit times (155,680 bits times in 1000Mbps mode or Jumbo Packet enabled mode) if DC bit is set in the MAC_Configuration register. | ||
When TBS is enabled in full-duplex mode and this bit is set, the bit indicates that the frame has been dropped after the expiry time has reached. | ||
2 | UF | Underflow Error |
This bit indicates that the MAC aborted the packet because the data arrived late from the system memory. The underflow error can occur because of either of the following conditions: | ||
The DMA encountered an empty Transmit Buffer while transmitting the packe.t | ||
The application filled the MTL Tx FIFO slower than the MAC transmit rate. | ||
The transmission process enters the suspended state and sets the underflow bit corresponding to a queue in the MTL_Interrupt_Status register. | ||
1 | DB | Deferred Bit |
This bit indicates that the MAC deferred before transmitting because of presence of carrier. This bit is valid only in the half-duplex mode. | ||
0 | IHE | IP Header Error |
When IP Header Error is set, the bit indicates that the Checksum Offload engine detected an IP header error. This bit is valid only when Tx Checksum Offload is enabled. Otherwise, the bit is reserved. If COE detects an IP header error, it still inserts an IPv4 header checksum if the Ethernet Type field indicates an IPv4 payload | ||
In full-duplex mode, when EST/Qbv is enabled and this bit is set, the bit indicates the frame drop status due to Frame Size error or Schedule Error. |