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Background: this is (I think) effectively a USB hub, with built in ethernet. This is the circuit as it is being used in the Raspberry Pi B rev. 2

The USB+ from the upstream port (0) is connected to the USB+ on only one of the two downstream ports (3) through a 360R resistor [seen in the very middle of the image]. The USB- is similarly connected to the same downstream port (but the - line).

My questions - why is this being done, and why to that particular port? Could it be done to the other port (2), or both of them, or none?

Segment of Raspberry Pi Schematic showing USB & Ethernet circuitry

The datasheet for the LAN controller is here: http://ww1.microchip.com/downloads/en/DeviceDoc/9512.pdf

The whole schematic is here: https://www.raspberrypi.org/wp-content/uploads/2012/10/Raspberry-Pi-R2.0-Schematics-Issue2.2_027.pdf

The part I have taken this image from is on page 3 of the schematic.

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    \$\begingroup\$ Good luck with DesignSpark PCB... Most awful electrical IDE I've used and yet the one I stick to because of experience. \$\endgroup\$
    – Mister Mystère
    Apr 13, 2015 at 13:27

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That's an 0R resistor, a fittable link. It looks like on the Model A there's no hub and only a single port, which is connected straight through. On the model B the resistor is not fitted.

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  • \$\begingroup\$ Thank you. I misread the schematic, of course the resistor value wouldn't wrap onto the next line! \$\endgroup\$
    – Tom H
    Apr 13, 2015 at 11:21

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