AM2434: Daisy chain connection using AM2434 Ethernet

Conor

Guru 10880 points

Part Number: AM2434

Hi,

I am considering making a daisy chain connection using AM2434's 2ch Ethernet.

When making a daisy chain connection, is it okay to use only one GMAC address? Or do it need two address?

Thanks,

Conor

over 1 year ago

0 Nilabh Anand over 1 year ago

TI__Mastermind 35732 points

Hi Conor,

When using GMAC with single mac address, it will act as a switch, basically formward packets on another port and to host port. So it should be fine.

0 Conor over 1 year ago in reply to Nilabh Anand

Guru 10880 points

Hi Nilabh,

Thank you for your answer.

The sentence was a little difficult to understand, so I'll add some additional information.
It is known that a certain Power Distribution Unit uses an external 3-port switch IC (built-in RSTP) and has two MAC addresses on the CPU. The image is as below.

In this case, does the CPU need two MAC addresses? Or is it possible to daisy chain connections with just one MAC address? I am wondering if it is possible to configure it like the image below.

Thanks,

Conor

0 Nilabh Anand over 1 year ago in reply to Conor

TI__Mastermind 35732 points

Conor said:
In this case, does the CPU need two MAC addresses? Or is it possible to daisy chain connections with just one MAC address? I am wondering if it is possible to configure it like the image below.

If you need two MAC ports then you will need two mac address. But if you want to operate it as a switch then a single mac address will work.

Please refer this for more details on understand the working of CPSW: https://software-dl.ti.com/mcu-plus-sdk/esd/AM243X/latest/exports/docs/api_guide_am243x/ENET_LWIP_CPSW_OPERATING_MODES.html

In SWITCH Mode- 1 mac addess

In DUAL MAC mode- 2 MAC Address

0 Conor over 1 year ago in reply to Nilabh Anand

Guru 10880 points

Hi Nilabh,

Thank you for your reply.

Does AM243x support RSTP function? If it is not supported, please let me know the model number that is supported by Sitara products.

Thanks,

0 Nilabh Anand over 1 year ago in reply to Conor

TI__Mastermind 35732 points

Hi Conor,

Conor said:
Does AM243x support RSTP function?

The CPSW peripheral can support RSTP based on following behaviour, but we have not tested it. You can go ahead and look through the configurations available in CPSW peripheral.

Conor said:
please let me know the model number that is supported by Sitara products.

(32) CPSW support for RSTP (AM335X - Linux) - Processors forum - Processors - TI E2E support forums

4.3. RSTP — Processor SDK Linux for AM335X Documentation

(32) AM625: RSTP support on AM62x - Processors forum - Processors - TI E2E support forums

0 Nilabh Anand over 1 year ago in reply to Nilabh Anand

TI__Mastermind 35732 points

The behaviours are:

To implement the RSTP it is necessary to:

1) Identify from which port came an Ethernet frame (RSTP BPDU input port)

2) Set from which port I want to send an Ethernet frame (RSTP BPDU output port)

3) A BPDU uses a Multicast address as MAC destination address, which must always be sent from a specific port, and moreover, contrary of the standard multicast address, the BPDU must not be forwarded once received. So the switch must be configured in such a way to support the described behavior.

So you will need to configure CPSW in dual mac mode the demo for the same is present in sdk(https://software-dl.ti.com/mcu-plus-sdk/esd/AM243X/latest/exports/docs/api_guide_am243x/ENET_LWIP_CPSW_OPERATING_MODES.html). For multicast handling you can read more in TRM (https://www.ti.com/lit/ug/spruim2h/spruim2h.pdf) chapter 12.2.1.4

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AM2434: Daisy chain connection using AM2434 Ethernet