I347-AT4 Datasheet, PDF (40/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

I347-AT4—Device Functionality
3.7.1
10/100/1000BASE-T Auto-Negotiation
The 10/100/1000BASE-T auto-negotiation is based on Clause 28 and 40 of the
IEEE802.3 specification. It is used to negotiate speed, duplex, and flow control over
CAT5 UTP cable. Once auto-negotiation is initiated, the I347-AT4 determines whether
or not the remote device has auto-negotiation capability. If so, the I347-AT4 and the
remote device negotiate the speed and duplex with which to operate.
If the remote device does not have auto-negotiation capability, the I347-AT4 uses the
parallel detect function to determine the speed of the remote device for 100BASE-TX
and 10BASE-T modes. If link is established based on the parallel detect function, then it
is required to establish link at half-duplex mode only. Refer to IEEE 802.3 clauses 28
and 40 for a full description of auto-negotiation.
After hardware reset, 10/100/1000BASE-T auto-negotiation can be enabled and
disabled via Register 0_0.12. Auto MDI/MDIX and auto-negotiation can be disabled and
enabled independently. When auto-negotiation is disabled, the speed and duplex can
be set via registers 0_0.13, 0_0.6, and 0_0.8, respectively. When auto-negotiation is
enabled the abilities that are advertised can be changed via registers 4_0 and 9_0.
Changes to registers 0_0.12, 0_0.13, 0_0.6 and 0_0.8 do not take effect unless one of
the following takes place:
• Software reset (registers 0_0.15)
• Restart auto-negotiation (register 0_0.9)
• Transition from power down to power up (register 0_0.11)
• The copper link goes down
To enable or disable auto-negotiation, Register 0_0.12 should be changed
simultaneously with either register 0_0.15 or 0_0.9. For example, to disable auto-
negotiation and force 10BASE-T half-duplex mode, register 0_0 should be written with
0x8000.
Registers 4_0 and 9_0 are internally latched once every time the auto-negotiation
enters the ability detect state in the arbitration state machine. Hence, a write into
Register 4_0 or 9_0 has no effect once the I347-AT4 begins to transmit Fast Link Pulses
(FLPs).This guarantees that sequences of FLPs transmitted are consistent with one
another.
Register 7_0 is treated in a similar way as registers 4_0 and 9_0 during additional next
page exchanges.
If 1000BASE-T mode is advertised, then the I347-AT4 automatically sends the
appropriate next pages to advertise the capability and negotiate master/slave mode of
operation. If the user does not wish to transmit additional next pages, then the next
page bit (Register 4_0.15) can be set to zero, and the user needs to take no further
action.
If next pages in addition to the ones required for 1000BASE-T are needed, then the
user can set register 4_0.15 to one, and send and receive additional next pages via
registers 7_0and 8_0, respectively. The I347-AT4 stores the previous results from
register 8 in internal registers, so that new next pages can overwrite register 8_0.
Note that 1000BASE-T next page exchanges are automatically handled by the I347-AT4
without user intervention, regardless of whether or not additional next pages are sent.
30