SNLS647G december 2019 – july 2023 DP83826E , DP83826I
PRODUCTION DATA
The DP83826 can determine if a “straight” or “crossover” cable is used to connect to the link partner. It can automatically re-assign to Td (MDI) channel and Rd (MDIX) channel to establish link with the link partner. Auto-MDIX resolution precedes the actual Auto-Negotiation process that involves exchange of FLPs to advertise capabilities. Automatic MDI/MDIX is described in IEEE 802.3 Clause 40, section 40.8.2. It is not a required implementation for 10BASE-Te and 100BASE-TX. Auto-MDIX can also be used when operating the PHY in Force Mode.
Auto-MDIX can be enabled or disabled in hardware, using the hardware bootstrap, or by register configuration, using bit[15] of the PHY Control Register (PHYCR, address 0x0019). When Auto-MDIX is disabled, the PMA is forced to either MDI (“straight”) or MDIX (“crossover”). Manual configuration of MDI or MDIX can also be accomplished using register configuration, using bit[14] of the PHYCR or hardware bootstraps in ENHANCED mode.