TM4C129DNCPDT Datasheet, PDF (1582/1946 Pages) Texas Instruments – Tiva Microcontroller

Ethernet Controller
Bit/Field
27
26
25
24
23
22
Name
TWOKPEN
reserved
CST
reserved
WDDIS
JD
Type
RW
RO
RW
RO
RW
RW
Reset
0x0
Description
IEEE 802.3as Support for 2K Packets
When set, the MAC considers all frames, up to 2,000 bytes in length,
as normal packets. This bit is only valid when the JFEN bit is set to 0.
When JFEN is set, configuring TWOKPEN has no effect on Giant Frame
status.
Value Description
0 If the JFEN bit is clear, the MAC considers all received frames
larger than 1,518 bytes (1,522 byes tagged) as Giant Frames.
1 Frames up to 2 KB are considered normal packets.
If the JFEN bit is clear, the MAC considers all received frames
larger that 2K bytes as Giant frames.
0x0
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x0
CRC Stripping for Type Frames
When set, the last four bytes (Frame Check Sequence FCS) of all frames
of Ether type ((Length/Type field greater than or equal to 0x0600) are
removed before forwarding the frame to the application.
Value Description
0 No bytes are removed.
1 The last four bytes are removed before forwarding.
0x0
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation.
0x0
Watchdog Disable
When this bit is set, the MAC disables the internal watchdog counter on
the receiver. The MAC can receive frames of up to 16,384 bytes.
When this bit is cleared, the MAC does not allow more than 2,048 bytes
(10,240 if JFEN is set to 1) of the frame being received. The MAC cuts
off any bytes received after 2,048 bytes.
Value Description
0 Watchdog counter enabled.
1 Watchdog counter disabled.
0x0
Jabber Disable
When this bit is set, the MAC disables the jabber counter on the
transmitter. The MAC can transfer frames of up to 16,384 bytes.
When this bit is clear, the MAC stops transmission if the application
sends out more than 2,048 bytes of data (10,240 if JFEN is set to 1).
Value Description
0 Jabber counter enabled.
1 Jabber counter disabled.
1582
Texas Instruments-Production Data
June 18, 2014