Data Sheet

Programming Interface — Ethernet Controller I210
455
8.12.2 Transmit Control Extended - TCTL_EXT (0x0404; R/W)
This register controls late collision detection.
The COLD field is used to determine the latest time in which a collision indication is considered as a
valid collision and not a late collision. When using the internal PHY, the default value of 0x40 provides a
behavior consistent with the 802.3 spec requested behavior. However, when using an SGMII connected
external PHY, the SGMII interface adds some delay on top of the time budget allowed by the
specification (collisions in valid network topographies even after 512 bit time can be expected). In order
to accommodate this condition, COLD should be updated to take the SGMII inbound and outbound
delays.
8.12.3 Transmit IPG Register - TIPG (0x0410; R/W)
This register controls the Inter Packet Gap (IPG) timer.
Reserved 23 0b Reserved.
RTLC 24 0b
Re-transmit on Late Collision.
When set, enables the I210 to re-transmit on a late collision event.
Note: RTLC configures the I210 to perform re-transmission of packets when a late
collision is detected. Note that the collision window is speed dependent: 64
bytes for 10/100 Mb/s and 512 bytes for 1000 Mb/s operation. If a late
collision is detected when this bit is disabled, the transmit function assumes
the packet has successfully transmitted. This bit is ignored in full-duplex
mode.
Reserved 31:25 Reserved.
Field Bit(s) Initial Value Description
Reserved 9:0 0x40
Reserved.
Write 0x40, ignore on read.
COLD 19:10 0x42
Collision Distance.
Used to determine the latest time in which a collision indication is considered as a
valid collision and not a late collision.
Reserved 31:20 0x0
Reserved.
Write 0x0, ignore on read.
Field Bit(s) Initial Value Description