Atmel Xplained Pro Evaluation Kit ATSAM4E-XPRO ATSAM4E-XPRO Hoja De Datos

SAM4E [DATASHEET]

Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14

1198



There is a transmit error such as too many retries or a transmit underrun.

To set TXGO, write TSTART to the bit 9 of the Network Control Register. Transmit halt does not take effect until
any ongoing transmit finishes.

If the DMA is configured for internal FIFO mode, transmission will automatically restart from the first buffer of the
frame. 

If a used bit is read mid way through transmission of a multi buffer frame this is treated as a transmit error.
Transmission stops, GTXER is asserted and the FCS will be bad.

If transmission stops due to a transmit error or a used bit being read, transmission will restart from the first buffer
descriptor of the frame being transmitted when the transmit start bit is rewritten.

31:0

Byte address of buffer

31

Used—must be zero for the GMAC to read data to the transmit buffer. The GMAC sets 
this to one for the first buffer of a frame once it has been successfully transmitted. 
Software must clear this bit before the buffer can be used again.

30

Wrap—marks last descriptor in transmit buffer descriptor list. This can be set for any 
buffer within the frame.

29

Retry limit exceeded, transmit error detected

28

Transmit underrun—occurs when the start of packet data has been written into the FIFO 
and either HRESP

 

is not OK, or the transmit data could not be fetched in time, or when 

buffers are exhausted. 

27

Transmit frame corruption due to AHB error—set if an error occurs while midway through 
reading transmit frame from the AHB, including HRESP errors and buffers exhausted mid 
frame (if the buffers run out during transmission of a frame then transmission stops, FCS 
shall be bad and GTXER asserted). 

26

Late collision, transmit error detected. 

25:23

Reserved

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