DP83867IR: MDI ports for 100Mbps, RGMII

Sreenivasa,

It seems TD_P_A、TD_M_A and TD_P_B、TD_M_B work as both transmitter and receiver. In case of DP83867IR at 100Mbps & RGMII, those pins work as below?

TD_P_A: Receiver +

TD_M_A : Receiver-

TD_P_B: Transmitter+

TD_M_B: Transmitter-

Regards,

Noriyuki Takahashi

Hi Sreenivasa,

You mentioned the below is correct, but it seems TD_P_A and TD_M_A  work as transmitter based on the 

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1005225/dp83867is-100-base-tx-mode-tx-and-rx-pins/3716400. Which is correct?

Noriyuki Takahashi said:

TD_P_A: Receiver +

TD_M_A : Receiver-

TD_P_B: Transmitter+

TD_M_B: Transmitter-

They also have several questions.

- In the post, we can see the comment as below. Does this mean that they don't need to care about TD_P_A works as receiver or transmitter?

"But if using auto-mdix, each pair can function as either RX or TX."

Regards,

Noriyuki Takahashi

Hello Noriyuki Takahashi

The below would help you understand batter.

8.4.3.9 Auto-MDIX Resolution

The DP83867 can determine if a straight or crossover cable is used to connect to the link partner. It can automatically re-assign channel A and B to establish link with the link partner, (and channel C and D in 1000BASE-T mode). 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 be enabled or disabled by register configuration, using bit 6 of the PHYCR register (address 0x0010). When Auto-MDIX is disabled, the PMA is forced to either MDI (straight) or MDIX (crossed). Manual configuration of MDI or MDIX can also be accomplished by register configuration, using bit 5 of the PHYCR register. For 10/100, Auto-MDIX is independent of Auto-Negotiation. Auto-MDIX works in both Auto-Negotiation mode and manual forced speed mode.

0X0010

MDI Crosssover Mode:

1x = Enable automatic crossover

01 = Manual MDI-X configuration

00 = Manual MDI configuration

Regards,

Sreenivasa

Sreenivasa,

How about the question as below?

Noriyuki Takahashi said:

You mentioned the below is correct, but it seems TD_P_A and TD_M_A  work as transmitter based on the 

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1005225/dp83867is-100-base-tx-mode-tx-and-rx-pins/3716400. Which is correct?

Regards,

Noriyuki Takahashi