RaspberryPi..Separating shared Usb and Ethernet.

[DRONE7]

Here is a simple way to separate the Usb and ethernet ports from the Pi's shared bus.
It costs $5, takes 10 minutes, involves no cutting or soldering, and is completely reversible.

I have tried it successfully using MoOde o/s but it should work with anything running Raspbian-Jessie or newer.

It should work for any Pi and any improvements would be most applicable to the earlier versions without wifi on-board. (as the wifi bus is separate from the usb bus anyway.)

These are the parts and setup for the alternate ethernet via gpio pins.
Super Cheap Ethernet for the Raspberry Pi: 5 Steps

Once that is up and working you can turn off the on-board ethernet port using these instructions..
Embedded Apocalypse: How to power off Raspberry Pi 3 USB or Ethernet ports


Although the gpio ethernet is limited in throughput it seems to work fine for the web interface and webradio streams.
File transfers and NAS use probably not so good ... but I don't have a NAS and use my Pi to listen to webradio and play files from local usb drives.

I would be interested in comments from anyone trying this or those with more linux knowledge than I who care to explain the pros and pifalls. (oops... should read 'pitfalls' but I kind of like 'pifalls' so leaving it )

 

[soundcheck]

It's 10MBit/s only.

 

[DRONE7]

It's 10MBit/s only.

That caveat was noted...

Although the gpio ethernet is limited in throughput it seems to work fine for the web interface and webradio streams.

 

[phofman]

What is the CPU load of the process when running the GPIO ethernet at max achievable speed?

 

[DRONE7]

ssh session, Pi playing webstream, and file transfer......

On a Pi-B. single core no overclocking.

 

[phofman]

Thanks a lot.

 

[DRONE7]

I was getting dropouts in web-stream audio while the ethernet device was maxed out.

However, without doing file transfer at the same time then the web-stream , ssh , and web-interface have been very stable and usb playback is reliable...

For my use it is more than acceptable,,

 

[phofman]

Bit banging the GPIOs vs. proper DMA of a real network card/usb controller do make a difference.

 

[DRONE7]

Yes, agreed.

Next experiment may be to use i2s for output to Dac, onboard ethernet for Nas, gpio ethernet device for web interface and webradio....and turn off the usb ports.....

"The infernal madness is only temporarily subdued by the blue smoke"

 

[phofman]

The onboard ethernet on your RPi is not hooked to the internal USB hub?

 

[JohnW]

As far as I'm aware with all Pi hardware everything is shared onto a single USB port (Ethernet and any other USB devices).

I can stream 384KHz over LAN and output to the DAC over USB at 384KHz bit accurate - so its not too bad...

What causes an issue is dropping the USB interface down to low speed mode (Say moving the mouse) - I guess the transaction between USB2.0 High speed and Low speed USB1.1 interface is not easy.