DP83869HM: EtherCAT

Hi, 

We recommend DP83826A for EtherCAT mainly because Beckhoff requires that the PHY configuration must not rely on configuration via the MII management interface, i.e., required features must be enabled after power-on3, e.g., by default or by strapping options.
For both DP83867 and DP83869, some of the features needed for EtherCAT such as Fast Link Drop can only be enabled via register configuration. 

Please let me know if you have any questions about this. 

Best,
J

Hi,

We are planning to implement EtherCAT interface in AM6442 processor, so we referred inTMDS64EVM they used two different PHY for Ethernet (DP83867IRRGZR/T) and EtherCAT (DP83869HRGZT) even though they have same functionality so is it necessary to use different PHY's or we can use one PHY for both communications.

Thank's

Rubigaa

Hi Rubigaa,

Because EtherCAT is a closed network, you may need additional equipment to communicate with external network. One simple solution may be to use two PHYs to differentiate one for EtherCAT communication and the other for Ethernet communication with the external world. 

Please let me know if you have any questions. 

Best,
J

Hi,J

Can we use a single PHY part number for both EtherCAT and Ethernet communications? Is it necessary to have different PHYs for different applications?

Regards,

Rubigaa

Hi Rubigaa, 

Yes, a single PHY can support this. However, the MAC will need to be able to distinguish the different packets of EtherCAT and Ethernet communications. 

Best,
J

Hi J,

sorry, can we use a same PHY (DP83867IRRGZR/T or DP83869HRGZT) for both EtherCAT and Ethernet communications? Is it necessary to have different PHYs for different applications?

Regards

Rubigaa

Hi Rubigaa, 

Same PHY can do this, but the MAC will need to be able to distinguish the different packets of EtherCAT and Ethernet communication from the external network. This will not be our PHY's issue. Rather, this will be the MAC's configuration. 

Best,
J

Hi J,

Thanks for your the reply,

The MAC's are independent in TMDS64EVM, 2 for EtherCAT and 1 for Ethernet but in TMDS64EVM they used different PHY's for EtherCAT(DP83869HRGZT) and Ethernet (DP83867IRRGZR/T). 

Please let me know the reason behind it.

Regards,

Rubigaa.

Hi Rubigaa, 

My team did not design TMDS64EVM so I cannot speak of the design decision behind TMDS64EVM. Please refer to the TMDS64EVM designers. 
However, based on the EVM User's Guide, it looks like they wanted to support both RGMII and MII by using DP83869 on 1G Ethernet. 



Best,
J