dav01
Posts: 6
Joined: Sat Mar 11, 2017 10:57 am

Ethernet via SDIO

Sat Mar 11, 2017 11:13 am

Planning a CM3 breakout board where I need 8x USB and 2x Ethernet, one for ext networking & one for "local offline gear".

Feels a bit unnecessary to push everything via the USB interface so I wonder if there are existing solutions/kernel-support for adding the additional networking in a smart way, i.e. the free SDIO?

nixy82
Posts: 42
Joined: Sat Sep 12, 2015 9:19 am

Re: Ethernet via SDIO

Sun Mar 12, 2017 10:54 am

I don't see why hanging 2 x 100M LAN9514 Wthernet controllers off a 480M bus is a problem, from what I've seen SDIO won't be any better.

The chips have an MTT USB controllers built in so USB bus contention isn't an issue

User avatar
rpdom
Posts: 15900
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Ethernet via SDIO

Sun Mar 12, 2017 12:30 pm

nixy82 wrote:I don't see why hanging 2 x 100M LAN9514 Wthernet controllers off a 480M bus is a problem, from what I've seen SDIO won't be any better.
That would only give you 7x USB and 2x Ethernet (the second LAN9514 would have to daisy-chain of one of the USB ports in the first one. So it doesn't quite meet the OPs requirements.

Also, hanging 8 x 480Mb USB + 2 x 100Mb LAN off one 480Mb USB port will probably be a bit of a bottleneck. Any way to spread that load across different interfaces would help.

nixy82
Posts: 42
Joined: Sat Sep 12, 2015 9:19 am

Re: Ethernet via SDIO

Sun Mar 12, 2017 3:10 pm

That would only give you 7x USB and 2x Ethernet (the second LAN9514 would have to daisy-chain of one of the USB ports in the first one. So it doesn't quite meet the OPs requirements..
You might have thought that, but that's not what I said...

.
Also, hanging 8 x 480Mb USB + 2 x 100Mb LAN off one 480Mb USB port will probably be a bit of a bottleneck. Any way to spread that load across different interfaces would help.
In my book OPs requirement for 8 x USB means this is never going to be pretty is it... ;)

User avatar
rpdom
Posts: 15900
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Ethernet via SDIO

Sun Mar 12, 2017 4:41 pm

nixy82 wrote:
That would only give you 7x USB and 2x Ethernet (the second LAN9514 would have to daisy-chain of one of the USB ports in the first one. So it doesn't quite meet the OPs requirements..
You might have thought that, but that's not what I said...
Ok, so how do you hang two LAN9512 controllers off a single 480M USB port while leaving all eight of their ports free?

nixy82
Posts: 42
Joined: Sat Sep 12, 2015 9:19 am

Re: Ethernet via SDIO

Sun Mar 12, 2017 7:11 pm

Ok, so how do you hang two LAN9512 controllers off a single 480M USB port while leaving all eight of their ports free?
I would start by extending the bus via a cheap USB hub chip myself, then connect up the appropriate combination of LAN9512/9514 chips as desired. :)

User avatar
rpdom
Posts: 15900
Joined: Sun May 06, 2012 5:17 am
Location: Chelmsford, Essex, UK

Re: Ethernet via SDIO

Sun Mar 12, 2017 8:04 pm

It would still help if at least one of the interfaces was running off a different bus, like the SDIO as used fir WiFi in the Pi3B and ZeroW.

dav01
Posts: 6
Joined: Sat Mar 11, 2017 10:57 am

Re: Ethernet via SDIO

Wed Jun 07, 2017 10:58 am

Hi, thanks for input.
I'm gonna try with daisy chaining two LAN9514 (7 usb ports will be ok)

I don't really need a high speed connection on the 2nd ethernet jack, so an option is to could off-load this to a SPI-based ethernet chip instead.


Talking about the wifi via SDIO, where can I find the schematic for that one?

6by9
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 7742
Joined: Wed Dec 04, 2013 11:27 am
Location: ZZ9 Plural Z Alpha, aka just outside Cambridge.

Re: Ethernet via SDIO

Wed Jun 07, 2017 12:19 pm

dav01 wrote:Hi, thanks for input.
I'm gonna try with daisy chaining two LAN9514 (7 usb ports will be ok)
You may need to do something clever on MAC address programming - viewtopic.php?f=98&t=180226&p=1147690
Software Engineer at Raspberry Pi Trading. Views expressed are still personal views.
I'm not interested in doing contracts for bespoke functionality - please don't ask.

Return to “Compute Module”