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Transmit IPG Register - TIPG (00410;R/W) — Intel
®
82575EB Gigabit Ethernet Controller
324632-003 Intel
®
82575EB Gigabit Ethernet Controller
Revision: 2.1 Software Developer’s Manual and EEPROM Guide
January 2011 365
14.3.66 Transmit IPG Register - TIPG (00410;R/W)
This register controls the Inter Packet Gap (IPG) timer. The recommended TIPG value to achieve 802.3
compliant minimum transmit IPG values in full and half duplex is 00702008h.
14.3.67 DMA Tx Control - DTXCTL (03590h; R/W)
This register controls whether an IP identification field scrolls on 15-bit or 16-bit boundaries in TSO
packets.
Field Bit(s)
Initial
Value
Description
IPGT 9:0 08h IPG Back to Back
Specifies the IPG length for back to back transmissions in both full and half
duplex.
Measured in increments of the MAC clock:
8 ns MAC clock when operating @ 1 Gb/s.
80 ns MAC clock when operating @ 100 Mb/s.
800 ns MAC clock when operating @ 10 Mb/s.
IPGT specifies the IPG length for back-to-back transmissions in both full
duplex and half duplex. Note that an offset of 4 byte times is added to the
programmed value to determine the total IPG. As a result, a value of 8 is
recommended to achieve a 12 byte time IPG.
IPGR1 19:10 08h IPG Part 1
Specifies the portion of the IPG in which the transmitter defers to receive
events. IPGR1 should be set to 2/3 of the total effective IPG (8).
Measured in increments of the MAC clock:
8 ns MAC clock when operating @ 1 Gb/s.
80 ns MAC clock when operating @ 100 Mb/s
800 ns MAC clock when operating @ 10 Mb/s.
IPGR 29:20 06h IPG After Deferral
Specifies the total IPG time for non back-to-back transmissions (transmission
following deferral) in half duplex.
Measured in increments of the MAC clock:
8 ns MAC clock when operating @ 1 Gb/s.
80 ns MAC clock when operating @ 100 Mb/s
800 ns MAC clock when operating @ 10 Mb/s.
An offset of 5-byte times must be added to the programmed value to
determine the total IPG after a defer event. A value of 7 is recommended to
achieve a 12-byte effective IPG. Note that the IPGR must never be set to a
value greater than IPGT. If IPGR is set to a value equal to or larger that IPGT,
it overrides the IPGT IPG setting in half duplex resulting in inter-packet gaps
that are larger then intended by IPGT. In this case, full duplex is unaffected
and always relies on IPGT.
The recommended TIPG value to achieve 802.3 compliant minimum transmit
IPG values in full and half duplex is 00601008h.
Reserved 31:30 00b Reserved
Read as 0b.
Should be written with 0b for future compatibility.