Hi all,

Does anyone know if there is a command (or some way in software) to turn off the power for any of the attached USB devices on the Raspberry Pi B+?

There isn't.

Use an in-line hardware switch.

This might be enough (all USB off - including the built-in Ethernet)

Disable
echo 0x0 > /sys/devices/platform/bcm2708_usb/buspower
Enable
echo 0x1 > /sys/devices/platform/bcm2708_usb/buspower

the PI (B+) has NO hardware in place to disconnect power to the USB ports!

it can detect a short, (USB power Fault) and then the USB power controller (P2553W6) will automatically block the USB power, but the PI cannot turn off the USB power using software. What it can do is bring the LAN9514 into sleep mode, but that does NOT turn the power off!

post edit, I learned the designers used a hack, so that the same signal that monitors an overload status can also be used to disable the power monitor, thus shut off USB power, so by previous remark was incorrect!

Its a single current monitor, so shutting it down affects all USB ports.

mahjongg wrote:the PI (B+) has NO hardware in place to disconnect power to the USB ports!

it can detect a short, (USB power Fault) and then the USB power controller (P2553W6) will automatically block the USB power, but the PI cannot turn off the USB power using software. What it can do is bring the LAN9514 into sleep mode, but that does NOT turn the power off!

Yes it can.

Issuing a USB Hub class request (CLEAR_FEATURE PORT_POWER) to port 2 on the LAN9514 will deactivate the USB output power switch.

There's an app for that:

https://github.com/codazoda/hub-ctrl.c

by watching the schematics of old modle A and B, the ubs powerline is hardwired directly without any possible control.
the schematic of the computer module shows, that the usb power seems to be not controled as well.

the full schematic of model A+ and B+ i can not find on the documents github at schematics section

what i see on my Modle B compared to my Modle B+, when i "sudo poweroff" it is, that connected usb devices on a Modle B stays powered on and at Modle B+ they turned off. so i think it is like "jdb" told, it is possible to control the power on a RPi Modle B+ (Modle A+).

jdb wrote:Yes it can...

PS.: does anybody know, why there is no full schematic on the github.com/raspberrypi/documentation/hardware/raspberrypi/schematics
section available for RPi Model B+ and A+ ?
(the partial schematics of Modle B+ is a kind of joke)

beta-tester wrote:PS.: does anybody know, why there is no full schematic on the github.com/raspberrypi/documentation/hardware/raspberrypi/schematics
section available for RPi Model B+ and A+ ?

Because no one has had the time to generate the full schematics in a generally usable format yet.

jdb wrote:

mahjongg wrote:the PI (B+) has NO hardware in place to disconnect power to the USB ports!

it can detect a short, (USB power Fault) and then the USB power controller (P2553W6) will automatically block the USB power, but the PI cannot turn off the USB power using software. What it can do is bring the LAN9514 into sleep mode, but that does NOT turn the power off!

Yes it can.

Issuing a USB Hub class request (CLEAR_FEATURE PORT_POWER) to port 2 on the LAN9514 will deactivate the USB output power switch.

There's an app for that:

https://github.com/codazoda/hub-ctrl.c

Thanks for the information! This will be usefull to reset my 3G modem if it stops responding

Won't

sudo udevadm trigger

not be easier to reset an errant 3G modem?

cancunia wrote:I came across this thread yesterday and can confirm that hub-ctrl with '-h 0 -P 2 -p 0' will turn off ALL of the USB ports and by the looks of things the Ethernet port off too. If there's any finer granularity than all or nothing possible, please let me know. Thx

The Ethernet going off too does not surprise me at all, since it is actually a USB device being driven by the USB hub chip.

I was aware that the B ran the USB power directly from the 5v rail, but was not aware that this was changed in the B+. If it is controllable on a port-by-port basis, this could be very useful. In addition to the obvious abilities to shut off USB devices to save power, or to power cycle them, you could power certain 5v non-USB devices from a USB port and switch them on and off at will, essentially providing four outputs running at 5v. Potentially very handy! I'll definitely have to remember that.

the USB current monitor can be turned off by disabling the current monitor, the LAN9512 has its own I/O, and the signal PRTCTL2 (pin 14) that normally monitors an overload can be programmed as output, and then can turn of the current monitor, which cuts USB current.

Another thread in this forum taks about this in detail, including a piece of schematic.

It is my understanding that on the B+ if you turn off the USB HUB you will turn Ethernet as well. You can not disable one or the other.

You can use the following commands to achieve this:

echo 0 > /sys/devices/platform/bcm2708_usb/buspower;
echo 1 > /sys/devices/platform/bcm2708_usb/buspower;

I have tried them by myself and unfortunately when I keep turning the USB HUB ON/OFF constantly, at some point the R-Pi hangs and I have to manually reboot it.

I'll try the hub-ctrl.c to see if it is more robust...

I tried hub-ctrl.c:

while (true) do hub-ctrl  -h 0 -P 2 -p 0 ; sleep 3; hub-ctrl  -h 0 -P 2 -p 1; sleep 57; done

it worked for 24hrs without any problem.

I tried hub-crtl.c with some success on a Pi 2 :

Reset ETH 0, and I lost my connection (have to reboot)

sudo ./hub-ctrl -h 0 -P 1 -p 0 ; sleep 3; sudo ./hub-ctrl  -h 0 -P 1 -p 1

Reset all USB and ETH

sudo ./hub-ctrl -h 0 -P 2 -p 0 ; sleep 3; sudo ./hub-ctrl  -h 0 -P 2 -p 1

Reset USB 4

sudo ./hub-ctrl -h 0 -P 3 -p 0 ; sleep 3; sudo ./hub-ctrl  -h 0 -P 3 -p 1

Reset USB 2

sudo ./hub-ctrl -h 0 -P 4 -p 0 ; sleep 3; sudo ./hub-ctrl  -h 0 -P 4 -p 1

Reset USB 3

sudo ./hub-ctrl -h 0 -P 4 -p 0 ; sleep 3; sudo ./hub-ctrl  -h 0 -P 4 -p 1

I didn't find how to reset USB 1.
I want to reset USB connection on USB modem, I think I can do it with that tool but it doesn't work well at the moment.

I know this is an old thread but I'm hoping an answer has been found for it. I'd like to attach an Arduino to my Model 2 Pi, but I don't want the Arduino to draw power from the USB port on the Pi (its default action). If the Arduino is supplied with 7+ volts on its RAW input, it will use that instead of USB power, but the power curve is terrible, the Arduino wastes a lot of energy.

It (the Ardiuono) has a 5V in, and will use either that or the USB port for power, whichever has the higher voltage. There's already a 5V rail in my circuit, but I can imagine the Pi flipping around if the voltages vary a bit between say 5.04V and 5.06V, for example.

So, is it OK to split open a USB cable and disconnect its power wire, then expect it to work properly ?

The reason for all of this is the Pi's USB power output isn't very strong, powering a USB WiFi dongle and 2 Arduinos won't work.

I don't know if this will help you or not, but your Pi2B (assuming that's what you mean by "model 2 Pi") can supply up to a total of 1.2A via its USB ports if you add...

...to your config.txt file. That's assuming that your Pi PSU can supply the extra current of course.

Hello,
I have a Raspberry Pi 2 B and I am experimenting witih hub-ctrl for power cycling the USB. For my applicatoin, I need to power on and off certain USB ports.

I found this code, contrary to what a previous poster said, power cylces all USB ports but NOT the ethernet. It successfully cuts the +5v power to all the USB.

sudo ./hub-ctrl -h 0 -P 2 -p 0 ; sleep 3; sudo ./hub-ctrl  -h 0 -P 2 -p 1

This works as a crude method of cycling the power, except I would rather use per port switching if possible. If I switch the -P flag for hub-ctrl to "-P 4" or "-P 5" it works individually for USB ports 2 and 3 as desired, but it only cuts the DATA signal from the USB and not the +5v power, so the devices don't fully power on and off.

Does anyone know of a solution to cycle the +5v power on individual ports via software? Thanks for any help!

Just tested this with the Pi 3 in case anyone is interested. Here is what I am seeing. The USB port numbering from the picture posted above:

Hub:Port -- Controlled port(s)
0:1 -- Controls the Ethernet port
0:2 -- Controls all four USB ports (not the Ethernet)
0:3 -- Controls USB Port 4
0:4 -- Controls USB Port 2
0:5 -- Controls USB Port 3

As best I can tell, USB Port 1 cannot be controlled individually. I was expecting 0:2 to map to USB Port 1, but it is being used to control all of the USB ports.