Ethernet Connectivity

James Jolliffe

Other Parts Discussed in Thread: TMS320C6655, TMS320C6657, AM3358

I have an application that will potentially use a TI TMS320C665X DSP and an AM335x ARM system processor. The AM335x has a gigabit ethernet switch integrated and I was thinking about connecting one port to the outside world and using the other port as the high speed communication interface with the TMS320665x. Do you see any issues in using Ethernet as the communication interface between the DSP and the ARM processor since both devices will reside on the same PCB? I realize ethernet was designed for long run networking solutions but thought that it should work for this application. Any thoughts or suggestions and/or special considerations to keep in mind...

over 12 years ago

0 Bart Stiller over 12 years ago

TI__Expert 5400 points

Hi James,

I don't see any reason there would be a problem connecting the two via ethernet over short distance. However, I am not well versed in either the DSP or ARM processor, so I'm going to move this over to the Sitara forum where they may have seen situations similar to yours before --

0 Biser Gatchev-XID over 12 years ago in reply to Bart Stiller

TI__Guru**** 393215 points

James,

Keep in mind that the AM335X EMAC does not support MAC-to-MAC connections. It expects a PHY on the MII interface.

0 James Jolliffe over 12 years ago in reply to Biser Gatchev-XID

Intellectual 960 points

Biser,

It sounds like I would need a Gigabit PHY between TMS320C6655/57 and AM335x as well as between second AM335x Port and the outside world since neither appear to have integrated PHY. I noticed that TMS320C6657 EVM uses a Marvell 88E1112 Gigabit Transceiver and the AM335x EvM uses a Qualcomm AR8031. Any thoughts on which PHY to use since TI does not appear to have a Gigabit Ethernet Transceiver. Also, any other considerations that you can think of in using an Ethernet connnection between these 2 devices residing on same PCB.

0 Biser Gatchev-XID over 12 years ago in reply to James Jolliffe

TI__Guru**** 393215 points

http://www.ti.com/product/dp83865 is a Gigabit transceiver by TI. I have no information if it has been used with the AM335X however. If you browse this forum (Search Community tool at top right of page) you will find what Gigabit PHYs are commonly used with the AM335X.

0 James Jolliffe over 12 years ago in reply to Biser Gatchev-XID

Intellectual 960 points

Biser,

I find it interesting that neither TI group for ARM or DSP chose this device for their EVMs. Do you see any issue connecting LAN connection of AM335x EVM with TMS320C6657 EVM LAN connection? I believe this should not be an issue but we will basically have 2 PHYs connected between Media Access Controller of ARM and DSP. Basically one on each MAC output.

0 Biser Gatchev-XID over 12 years ago in reply to James Jolliffe

TI__Guru**** 393215 points

There should be no hardware issues connecting the two EVM Ethernet ports.

0 -DK- over 12 years ago in reply to James Jolliffe

TI__Mastermind 27890 points

James Jolliffe said:
I find it interesting that neither TI group for ARM or DSP chose this device for their EVMs.

James,

This device was not a TI product at the time the EVM's in question were designed. Nothing sinister here. ;)

0 James Jolliffe over 11 years ago in reply to Biser Gatchev-XID

Intellectual 960 points

I am now looking for solution per previous discussion to connect TMS320C6655 DSP to AM3358 ARM via EMAC. The 6657 DSP is an SMGII MAC to be connect to AM3358 which is an RGMII MAC interface. You previously noted that AM335x EMAC does not support MAC to MAC connnection. Could I use an RGMII to SGMII bidirectional ethernet bus converter like the MAX24287 to bridge the 2 EMACs together?

Note:

The MAX24287 Ethernet bus converter is a flexible, low cost Ethernet interface conversion device for interfacing a parallel gigabit media independent interface (GMII)/MII interface to a serial GMII/1000BASE-X interface.

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Ethernet Connectivity