EtherCAT master on AM3358?

Hi Gordon,

I'm not an expert on this, but as far as I know the EtherCAT master stack is implemented over the CPSW under Linux.

The question about the stack is somewhat separate from the question of port, I hope, since an EtherCAT master only needs a 'raw ethernet' packet interface; it does not have any of the clever packet-updating stuff that a slave has to do. So EtherCAT itself is a bit of a red herring.  If the NDK + SYS/BIOS can run over the PRU-ICSS port, then surely any other high-level stack can be adapted to do so as well.

What we need to know is whether the AM3358 can switch ethernet packets over its PRU-ICSS subsystem without needing custom PRU work (as we hope), or whether whatever PRU customisations the AM3359 has to support EtherCAT slaves are also required for Ethernet over those ports generally.

Gordon

Perhaps this post by Vinesh Balan will answer your question: http://e2e.ti.com/support/arm/sitara_arm/f/791/p/362005/1271636.aspx#1271636

I was aware of those posts, which is why I have confidence we can do what we want on the AM3359.  The question is whether that is still true on the AM3358.  My instinct is 'yes', but I am finding it difficult to determine what the differences between the 3358 and 3359 are.  The 3358 has a 1 GHz version and possibly greater availability, so it is a pressing question.

We may just by the 3358s and punt, but it would be nice if anyone were able to give us more guidance.

Gordon

The last two posts are both helpful, but appear to be saying 'No' and 'Yes' respectively.

I'm going with 'Yes', because reading TRM Rev K, the items marked with '*' don't actually say 'only available on AM3357 and AM3359', they say 'used by EtherCAT', and EtherCAT [slave] is only available on those processors.  That isn't quite the same thing.

I am guessing that there's either an EtherCAT certification issue, or some additional PRU functionality to support an EtherCAT slave, on the AM3357 and AM3359.  We'll see how we go...

For EtherCAT slave, you need either AM3357 or AM3359. For EtherCAT master, any of AM335x family will work because for Master you can use the standard Ethernet ports.

Yes, but we want to use the PRU-ICSS port, because we also have an ethernet link and normal TCP/IP stack through the CPSW.  We want our realtime EtherCAT link to be decoupled from any activity going on through the CPSW, which we understand shares a switch between its two ports.