AM6548: EtherCAT PRU-ICCS compatibility with RMII PHY

Robert McGaughey

Part Number: AM6548

HI,

Is it possible to use an RMII PHY with the AM6548 processor and use it as an EtherCAT slave? The EtherCAT slave demo for the TMD654IDEVM board has explicit instructions to modify the board to change the PHY from RGMII to MII mode. The EVM board is using DP83867IRPAPT PHY which has a 64-pin package, but for layout reasons, we would like to go with a 48-pin package such as the DP83867CRRGZ if possible.

Thanks,

Robert

9 months ago

0 Ashwani Goel 9 months ago

TI__Genius 17380 points

Hi Robert,

As per https://download.beckhoff.com/download/document/io/ethercat-development-products/an_phy_selection_guidev2.7.pdf

2.1 Ethernet PHY Requirements for EtherCAT ESCs which support Ethernet Physical Layer use MII interfaces, some do also support RMII/RGMII interfaces. Since RMII/RGMII PHYs include TX FIFOs, they increase the forwarding delay of an EtherCAT slave device as well as the jitter. RMII/RGMII is not recommended due to these reasons.

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I am adding HW expert for layout related part.

Best Regards

Ashwani

0 Pekka Varis 9 months ago in reply to Ashwani Goel

TI__Mastermind 23360 points

As Ashwani pointed to above, EtherCAT subdevice (slave) must use MII, RMII is not supported.

Also please note AM6548 EtherCAT subdevice support is limited to the 6.3 RTOS Processor SDK which has limited support and has not gone through certifiction. The EtherCAT support on https://www.ti.com/product/AM6442 and related https://www.ti.com/product/AM2434 family is certified and generally supported. Is there a reason why you'd want to use AM6548 instead of a paet from one of these families?

Pekka

0 Kallikuppa Sreenivasa 9 months ago

TI__Guru*** 135168 points

Hello Robert,

Please Refer below, interfaces supported by DP83867 devices

https://www.ti.com/lit/ds/symlink/dp83867ir.pdf

Regards,

Sreenivasa

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AM6548: EtherCAT PRU-ICCS compatibility with RMII PHY