This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AM2634: Purpose of CPSW - Port 0

Part Number: AM2634


Dear Team,

I'm working on ethernet application for our custom board,

while reading the data sheet I found it has 3 ethernet port in which port 0 used for internal only

So what the mean of that and what's the purpose on PORT 0 

  • Hi Vikas,

    • CPSW 3G is a 3 port ethernet subsystem
    • 2 ports are MAC ports (MAC Port-1 and MAC Port-2) and 1 CPPI packet streaming interface port, (port-0 or CPPI port: Communications Port Programming Interface).
    • The port-0 is referred to the CPDMA host port
    • The port-1 and port-2 are referred to the interfaces RGMII/RMII/MII
    • The AM263x cannot support RMII/MII mode because of pin limitations. Custom board based on it with enough pins can support RMII/MII mode. This is the reason no out of box example in the SDK is configured for RMII mode.
    • CPSW can be operated in 2 modes majorly: MAC mode and Switch mode
    • In Switch mode, packets are forwarded to Host + Other mac ports and packet forwarding is enabled
    • In MAC mode, packets are only given to the Host (port 0).
    • Generally the meaning of internal here is that it is the CPDMA host port is internal port. Whatever data comes from external world and goes to the R5F for processing will pass through the port-0 and whatever data is to be sent out from MAC port-1 or MAC port-2 coming from R5F will go through the Host port as it has the CPDMA interface.
    • Whatever packets are received on the AM263x device will be received on the MAC ports and then either routed out to other MAC ports (this can be done using the ALE port mask) or send it to host port-0 where the CPDMA will pick it up and R5F can consume it.

    Hope the above points gave you a clarity on CPSW. You can read the TRM chapter 13.2.1 on CPSW to understand it deeper. By June we will also be releasing a chapter on CPSW on mcu_plus_academy which is a place to quickly understand and get started on AM26x devices. 

    Regards,
    Shaunak