IP1001 LF
Data Sheet
3.5
Auto MDI/MDIX Crossover
The IP1001 implements auto-crossover function, that is, users don’t have to care using a crossover or
non-crossover cable. Its pin mapping in MDI and MDIX modes is shown in the following table. If IP1001
interoperates with a device that does not implement auto MDI/MDIX crossover, the IP1001 makes the
necessary adjustment prior to performing auto-negotiation. If the IP1001 interoperates with a device that
implements auto MDI/MDIX crossover, a random algorithm as described in IEEE 802.3 section 40.4.4
determines which device performs the crossover.
When the IP1001 interoperates with a 10BASE_T PHY or a PHY that implements auto-negotiation, IP1001
decides the MDI/MDIX by the presence of link pulses. However, when interoperating with a 100BASE_TX
PHY that does not implement auto-negotiation (i.e. link pulses are not present), IP1001 uses signal energy of
receiving MLT3 signals to determine whether or not to crossover.
The auto MDI/MDIX function is turned on automatically after hardware reset and users can disable it by
programming MII register 20.2. User can check if IP1001 is in MDI or MDIX type by reading MII register 17.11.
Auto MDI/MDIX function is not affected by disabling auto-negotiation function.
Pin
MDI
MDIX
1000BASE-T 100BASE-TX 10BASE-T
1000BASE-T 100BASE-TX 10BASE-T
MDI[0]P/M
MDI[1]P/M
MDI[2]P/M
MDI[3]P/M
BI_DA+/-
BI_DB+/-
BI_DC+/-
BI_DD+/-
TX+/-
RX+/-
Unused
Unused
TX+/-
RX+/-
Unused
Unused
BI_DB+/-
BI_DA+/-
BI_DD+/-
BI_DC+/-
RX+/-
TX+/-
Unused
Unused
RX+/-
TX+/-
Unused
Unused
3.6
Polarity Correction
The IP1001 performs polarity correction without any manual setting. It corrects polarity errors on the receive
pairs in 1000BASE-T and 10BASE-T modes automatically.
In 1000BASE-T mode, polarity correction is based on the sequence of idle symbols. In 10BASE-T mode,
polarity correction is based on the detection the polarity of valid normal link pulse and idle pulse. In
100BASE-TX mode, the polarity does not matter.
22/48
Dec. 18, 2007
IP1001-DS-R06
Copyright © 2006, IC Plus Corp.
ETC [ ETC ]
