[DP83867] Configuration for 1000M Ethernet compatible for 100M Ethercat

Zhou Fang67

Other Parts Discussed in Thread: DP83867E

Hi Expert,

My customer is considering DP83867 in their system right now. They need DP83867 to be compatible for both 1000M Ethernet and 100M Ethercat.

1. Does DP83867 support both 2 modes with the same HW implementation? should we use RGMII mode?

2. For RJ45 connector, could DP83867 swap TD_P/M_A with TD_P/M_D(C/B) or other transmitting ports can be swapped with each other randomly if Auto_MDIX is enabled? Any rules between to connect TD_P/M_ABCD to RJ45 connector?

Thanks a lot.

Zhou

over 8 years ago

0 Rob Rodrigues over 8 years ago

TI__Mastermind 19780 points

Hi Zhou,

1. RGMII and MII are not supported by the same HW configuration. GMII and MII can be used with the same hardware configuration. When using EtherCAT, I'd recommend using MII mode for low latency.

2. The channels cannot be swapped randomly. Auto_MDIX swaps channel A & B, and C & D. This allows use of straight-through cables and crossover cables. See this link for a description: www.computercablestore.com/straight-through-crossover-and-rollover-wiring
Please follow the connections in the DP83867E EVM. You may also reverse the order of the channels, this is referred to as mirror mode. See a thread based on mirror mode: e2e.ti.com/.../505890

Best Regards,

0 Zhou Fang67 over 8 years ago in reply to Rob Rodrigues

TI__Expert 4250 points

Hi Rob,

Thanks for your answer.

There is one more question. From BECKHOFF app note (download.beckhoff.com/.../an_phy_selection_guidev2.3.pdf), the PHYs have to provide an MII or RMII interface for Ethercat slave. MII and RMII are defined with 10/100M PHY.

Does Ethercat slave can be implemented with GMII or RGMII with Gig/1000M PHY?

Thanks.
Zhou

0 Rob Rodrigues over 8 years ago in reply to Zhou Fang67

TI__Mastermind 19780 points

Hi Zhou,

What EtherCAT slave controller will you be working with? I am not aware of a slave controller at the moment for gigabit Ethernet. We have been engaged with discussions about this, but nothing public yet.

For EtherCAT you should stick with 10/100 but if you need the system to also support 1000 Ethernet, then you will need a PHY like the DP83867.

Regards,

0 Zhou Fang67 over 8 years ago in reply to Rob Rodrigues

TI__Expert 4250 points

Hi Rob,

Thanks for your information.
The confusing thing is that whether DP83867 can support 10/100(supprot Ethercat) and 1000 at the same time with conpatible HW design? I don't figure out a conclusion yet.

Thanks

Zhou

Interface

Interface forum

[DP83867] Configuration for 1000M Ethernet compatible for 100M Ethercat