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AT32F435/437
Series Reference Manual
2022.11.11
Page 594
Rev 2.03
when all the data in the buffer are read completely. The own bit of the frame’s first
descriptor can be set only after subsequent descriptors for the same frame have
been set.
Bit 30
IC
rw
Interrupt on completion
When set, this bit sets the transmit interrupt bit (EMAC_DMASTS bit [0]) after the
present frame has been transmitted. This bit is valid only when the LS bit is set
Bit 29
LS
rw
Last segment
When set, this bit indicates that the buffer contains the last segment of the frame.
When this bit is set, neither TBS1 nor TBS2 cannot be cleared in the TDES1.
Bit 28
FS
rw
First segment
When set, this bit indicates that the buffer contains the first segment of the frame
Bit 27
DC
rw
Disable CRC
When set, the MAC does not append a CRC field to the end of the transmitted
frame. This bit is valid only when the FS bit is set (TDES0[28]=1).
Bit 26
DP
rw
Disable pad
0: The MAC automatically adds padding to a frame shorter than 64 bytes, and the
CRC field is added despite the state of the DC (TDES0[27]). This bit is valid only
when the FS bit is set (TDES0[28]).
1: The MAC does not automatically add padding to a frame shorter than 64 bytes.
Bit 25
TTSE
rw
Transmit time stamp enable
When this bit is set, the IEEE1588 hardware time stamp is activated for the transmit
frame described the descriptor. This bit is valid only when both the TSE
(EMAC_PTPTSCTRL[0]) and FS bits (TDES0[28]) are set.
Bit 24
Reserved resd
Kept at its default value.
Bit 23: 22 CIC
rw
Checksum insertion control
These two bits control the checksum calculation and insertion, as shown below:
00: Checksum insertion disabled
01: Only IP header checksum calculation and insertion are enabled
10: IP header checksum and data checksum calculation and insertion are enabled,
but pseudo-header checksum is not calculated.
11: IP header checksum and data checksum calculation and insertion are enabled,
and pseudo-header checksum is calculated.
Bit 21
TER
rw
Transmit end of ring
When set, it indicates that the descriptor list reached its final descriptor. The DMA
returns to the start address of the list, creating a descriptor ring.
Bit 20
TCH
rw
Second address chained
When set, it indicates that the TBS2 bit in the TDES1 refers to the second descriptor
address rather than the second buffer address. TDES0[21] takes precedence over
TDES0[20]. This bit is valid only when the TDES0[28] is set.
Bit 19: 18 Reserved resd
Kept at its default value.
Bit 17
TTSS
rw
Transmit time stamp status
This bit is used as a status bit to indicate that a time stamp is captured for the
described transmit frame. When this bit is set, it indicates the time stamp of the
transmitted frame described by the descriptor has been captured, which are stored
in the TDES2 and TDES3. This bit is valid only when the LS bit is set (TDES0[29]).
Bit 16
IHE
rw
IP header error
When set, it indicates that the MAC transmitter detected an error in the IP data
packet header. For IPv4 frames, the MAC checks whether the length field in the
IPv4 datagram does match the number of he received IPv4 data. If there is a
mismatch, an error is given. For IPv6 frames, an error is reported when the header
length is not 40 bytes. Furthermore, the length/type field value for an IPv4 or IPv6
frame must match the IP header version. For IPv4 frame, an error is reported and
this bit is set if the header length field value is shorter than 0x5.
Bit 15
ES
rw
Error summary
This bit indicates the logical OR of the following bits:
TDES0[14]: Jabber timeout
TDES0[13]: Frame flush
TDES0[11]: Loss of carrier
TDES0[10]: No carrier
TDES0[9]: Late collision
TDES0[8]: Excessive collision
TDES0[2]: Excessive deferral
TDES0[1]: Underflow error
TDES0[16]: IP header error