AM6442: MAC2MAC usage

Zekun Bai

Expert 3565 points

Part Number: AM6442

Tool/software:

Customer are using AM64 to implement CPSW RMII MAC2MAC.

Do you have any guide about pin connection regarding RMII?

Thanks

Zekun

4 months ago

0 Pekka Varis 4 months ago

TI__Mastermind 27050 points

For SW this MAC to MAC is a "fixed-link" connection see standard Linux documentation, so device tree you just call it "fixed-link". This will bypass auto-negotiation for speed. From SW this (do not auto-negotiate) is the only special thing about not having PHY's. See https://www.kernel.org/doc/Documentation/devicetree/bindings/net/ethernet-controller.yaml and also lots of e2e posts about this like https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1278876/tda4vh-q1-how-to-setup-the-mcu-cpsw2g-tx-clock-in-the-fixed-link-mode-within-rgmii? and others from there.

For HW we do not have an RMII to RMII guide. We implement a standard RMII, so design needs to meet the timing of RMII (see for example https://e2e.ti.com/support/processors-group/processors/f/processors-forum/366759/am335x-rmii-direct-connection-between-two-devices ). I believe RGMII at 100M Ethernet will be simpler to design, so I'd recommend using that instead.

Pekka

0 Zekun Bai 4 months ago in reply to Pekka Varis

TI__Expert 3565 points

Hi Pekka

Thanks for answer. I have forward the link to customer.

Could you help to check if customer HW signal connection for MAC2MAC?

Regards

Zekun

0 Zekun Bai 4 months ago in reply to Pekka Varis

TI__Expert 3565 points

The reason using RMII is pin number restriction, Pekka. So RMIi is used in customer system.

0 Daolin Qiu 4 months ago in reply to Zekun Bai

TI__Genius 16315 points

Hi Zekun,

Zekun Bai said:
Could you help to check if customer HW signal connection for MAC2MAC?

Let me loop in a HW expert to better comment on your request. Please note, that since MAC-to-MAC is something we haven't been able to test specifically yet (no hardware platform for this), the input they can offer might be limited.

Please kindly ping this thread again if you don't receive a response by Wednesday.

-Daolin

0 Zekun Bai 4 months ago

TI__Expert 3565 points

HI Daolin

Thanks for your help here.

I will keep an eye on this.

Regards

Zekun

0 Kallikuppa Sreenivasa 4 months ago in reply to Zekun Bai

TI__Guru**** 191119 points

Hello Zekun,

Please refer below thread for reference for feasibility.

(31) TDA4VM: The Driver Development for RMII Connection between Main cpsw9g port1 and MCU cpsw2g port1 (RMII for MAC to MAC) - Processors forum - Processors - TI E2E support forums

Dave mentioned we may have tested the MAC-MAC interface using the RGMII nut not sure if we have tested RMII.

From the hardware stand-point it may be feasible but this is not something that has been tested.

Regards,

Sreenivasa