Don't power USB when sleeping

Question

There are a lot of articles on how to keep a USB device powered when sleeping, but I want to do the opposite: power down a USB hub when putting my laptop to sleep. (The USB hub has a really bright blue light which wastes energy and is annoying when I try to sleep)

There are two things connected to the hub: an external harddisk (which has an external power supply which I cut off when the computer sleeps) and a keyboard

Things I already tried (In the device manager, right click on start --> device manager):

• Check "allow the computer to turn down this device to save power" for the USB hub and connected keyboard (was actually already turned on by default)
• Uncheck "Allow this device to wake the computer" (for the keyboard, checkbox is disabled for USB hub)

These options are not available for my external disk.

Does anybody know what I could do to power the USB hub down at night (except for the obvious but annoying disconnecting the USB hub)?

EDIT: I would also like to do this for ONLY the USB hub, so the other USB ports should keep power (I use my mouse to wake the computer and one of the other ports to charge my phone).

Answer 1

The LED will not be connected to the hub's logic circuits as there is no need for it to be - it will simply light up whenever power is applied. You can confirm this by plugging it into a wall socket, power strip, or backup battery that has a USB charging port.

What this means is that there is no way to disable the LED while the hub is plugged in - unless your particular laptop offers a hardware feature to completely power down the port. Such a feature should be exposed in the BIOS/UEFI interface, but if it doesn't exist then there's no avenue for Windows or any other software to control this either.

Furthermore, on a device with so few ports the chances are slim that individual control of them would be offered. As such it seems very unlikely there's a way to accomplish your goal as stated, especially since your scenario requires some of the ports to listen for wake events from your mouse.

As a solution I would offer the following suggestions:

• Obtain a hub without an LED or with a switch
• Obtain a USB A to A extension cable with an inline switch
• Cover the LED with a piece of electrical tape if you're not worried about its appearance
• Modify your existing hub to disable the LED, or add a switch

Answer 2

You can find an option for that in the BIOS too. Check "power management"

Answer 3

The function to turn power off a port can be accomplished, but only on a certain kind of hubs.

CASE_1: You have a hub that is an officially-certified bus-powered hub. According to USB specification v.2.0 for bus-powered hubs,

"Power to external downstream facing ports of a bus-powered hub must be switched"

see, section 7.2.1.1. This means that the hub must have "high-side" power switches, and hub controller IC must have means to turn these switches on/off. If a USB host sends USB command to reset its port with hub attached, the hub must turn VBUS power OFF on all downstream ports. Unfortunately, vast majority of "el-cheapo" hub manufacturers ignore this mandatory requirement, and have VBUS power derived directly from host power, from the cable. It is very unlikely that you can find the "correct hub" on store shelves. I would say "never". This leads us to Case_2.

CASE_2: You have a junk bus-powered hub with "captive cable", and it has an illegal ganged non-controllable power to its downstream ports. In this case you must have a computer that does have the power switching capability on its ports. This might be on many laptops, and maybe on few high-end industrial-grade desktop PC. Then, if you manage to perform internal port disable function on host controller, VBUS will be disabled, and hub power will be gone. Unfortunately this is very unlikely, since all ports are controlled by USB driver, which won't stop and will proceed with port enable, USB detection and enumeration, so VBUS will be enabled. So this is mostly a theoretical option.

CASE_3: Yet another way to disable VBUS on downstream ports of a hub is to have a version of self-powered hub (with power coming from AC-DC adapter) that has built-in downstream power switches, usually with current-limiting function. See Section 7.2.1.2 and Figure 7-43 of USB 2.0 Specifications, and also Section 11.11. Again, a self-powered hub is allowed not to have these expensive switch ICs, so vast majority of hub manufacturers skip this option, and put no control over downstream VBUS. Funny, the USB speculations still have a clause saying,

"Although a self-powered hub is not required to implement power switching, the hub must support the Powered-off state for all ports."

see Section 11.11, third paragraph. I have never seen this kind of hubs. No wonder that you can seldom find ANY hub at local electronics store that carries USB-IF certification logo.

The only hubs that comply with Hub Port Power Control requirements are the hubs that are used in official USB-IF certification process, so-called "Gold Tree" devices. One of the "good hubs" was made by D-Link, however there is no guarantee that the off-the-shelf mass-produced variant has all power-switch ICs populated and not bypassed by either poly-fuses or just shorts. So you are likely out of luck even in this case.

The last resort would be to cut the red wire in USB cable and put there a electro-mechanical switch, a relay, or a high-side switch, as suggested by Antonin. Then you need to find out some means to turn it off when PC goes to deep sleep, feed it from internal 5V rail, or something.

Answer 4

There is not a software based sollution since all od the USBs are probubly on a same circuit. But if you are ok with HW sollutions, jsut get (or create one yourself) an USB cord with a switch on a 5V+ rail.