TLK110 Datasheet, PDF (34/104 Pages) Texas Instruments – Industrial Temp, Single Port 10/100Mbs Ethernet Physical Layer

TLK110
SLLS901A – DECEMBER 2011 – REVISED FEBRUARY 2012
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As described, the link partner configuration and abilities, whether they use the auto negotiation and/or
activate a crossover mechanism, greatly influence the method picked by the crossover function to
determine if and how to cross. While in 10BT all possible configurations will results link establishment, in
100BT several configurations may not results link establishment. Table 5-3 describes all possible
configurations for 100BT and the link establishment results accordingly. In Table 5-3, when not in ANEG,
the link partner is assumed to be in force-100BT mode.
PHY1
ANEG AMDIX
+
+
+
+
+
–
+
+
+
–
–
–
+
+/–
PHY2
ANEG AMDIX
+
+
+
–
+
–
–
–
–
–
–
–
–
+
Table 5-3. Link-Pair Scenarios
Link
Established
V
V
V
V
V
V
V*
Remarks
Full automated link establishment
Full Automated since one of the link partners is in AMDIX
Link will be established only if both sides are configured in Force MDI or
MDIX in a matched manner:
• MDI vs. MDIX for non-crossed cables
• MDIX vs. MDIX for crossed cables
• MDI vs. MDI for crossed cables
When one of the sides is in Force 100BT and the other side is in ANEG, the
Force 100BT side must also be at force MDI or MDIX according to IEEE in
order to establish a link. This case is fully Automated since one of the link
partners is in AMDIX mode.
Link will be established only if both sides are configured in Force MDI or
MDIX in a matched manner:
• MDI vs. MDIX for non-crossed cables
• MDIX vs. MDIX for crossed cables
• MDI vs. MDI for crossed cables
Link will be established only if both sides are configured in Force MDI or
MDIX in a matched manner:
• MDI vs. MDIX for non-crossed cables
• MDIX vs. MDIX for crossed cables
• MDI vs. MDI for crossed cables
According to IEEE spec, a link could not be established in this scenario.
However, the TLK110 offers a unique mode, Enhanced AMDIX Mode, that
allows link establishment in this scenario as well. In this mode PHY2
(TLK110) while configured to force 100BT mode will adjust the AMDIX
mechanism timers to allow link establishment. When operating in this mode,
the TLK110 will be able to establish a link in all other scenarios as well. This
mode is not IEEE compliant and can be configured by setting bit 5 of register
0x0009 (SWSCR1)
The crossover mechanism can be turned off and forced to the MDI or MDI-X state by setting configuration
pin MDIX_EN (Pin 31), whose state is latched during power-up reset. When MDIX_EN is set to ‘0’, then
the crossover mechanism is disabled and the PHY operates in MDI or MDI/X mode respectively. If the pin
is set to '1', then the crossover mechanism is enabled and MDI/MDI-X state is selected during operation.
The auto-MDI/MDI-X crossover function is controlled by register PHYCR (0x0019) bits [15:14]. MDI/MDI-X
status can be read through register PHYSTS (0x0010) bit 14.
5.5 Auto Negotiation
The auto-negotiation function, described in detail in IEEE802.3 chapter 28, provides the means to
exchange information between two devices and automatically configure both of them to take maximum
advantage of their abilities.
34
Architecture
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