Recipe 3.10. Resolving Hung USB Devices

Problem

You are having problems with a USB device one or more devices stop functioning or the system hangs when another device is connected.

Solution

Ensure the device driver is installed first

A majority of USB problems occur from connecting the device before Windows knows what the device is, so it cannot find or install the proper device driver. This results in the device being classified as an "unknown device" to Device Manager and it will stay there forever until corrected. To clear an unknown device:

1. Disconnect the USB device.

2. Click Start, then right-click My Computer and select Properties.

3. Select the Hardware tab, then click Device Manager.

4. Review the device list to find Unknown Device.

5. Right-click Unknown Device, and select Uninstall and follow the prompts to remove the device. Close the Device Manager and My Computer Properties dialogs.

6. Install the device drivers for your USB product, then follow the instructions to know when it is OK to connect the device.

7. Connect the device only when prompted.

Ensure adequate power to device

A single USB device may draw a maximum of 500 mA or 2.5 watts from any single USB hub connection. Some hubs cannot provide enough power for one or more devices that draw maximum power. Try disconnecting all other USB devices, then connect only the problematic device to see whether it functions properly. If it does, you will need to use a separately powered hub for one or more devices to ensure there is enough power for all of them.

Reset hardware

Shut down your PC. Disconnect the power from all devices. Restart your PC and boot fully into Windows. Reconnect the power to your devices to allow Plug and Play settings to refresh.

Use the root hub

To avoid data signal and cabling problems, if the device is plugged into a secondary hub, disconnect it from the secondary hub and reconnect it to the root hub (direct USB port) on your PC. If the device is already connected to the root hub (main system), try connecting it to a USB hub to improve power and signal conditioning.

Change cables

Not all cables are created equal or are of high-enough quality to pass data signals properly for high-speed USB 1.1 or higher-speed USB 2.0 devices. Try a shorter cable or a cable from a different manufacturer.

Configure the USB root hub to use an IRQ

1. Click Start, then right-click My Computer and select Properties.

2. Select the Hardware tab, then click Device Manager.

3. Under Universal Serial Bus Controllers, locate the Standard OpenHCD USB Host Controller entries.

4. Right-click each of the Standard OpenHCD USB Host Controller items, and select Properties, then the Resources tab.

5. In the Resource type column under Resource Settings, make sure there is an IRQ assignment listed. If no IRQ assignment is shown, you need to go into BIOS setup to configure the USB controller hardware to use an IRQ.

6. Restart your PC and access the BIOS setup program.

7. Find the parameters for assigning an IRQ to the USB interface and set it to Yes or Enable.

8. Restart your PC and recheck the USB devices for proper functionality.

Update your PC's BIOS firmware

It is not unusual to learn that the BIOS that runs your PC's system board has a few kinks and flaws. Plug and Play features existed long before USB devices were invented, so the implementation of Plug and Play in your BIOS may not be up to the task of properly handling USB. Check your PC maker's web site for BIOS revisions for your system board, and download and install the latest version.

Discussion

USB technology is perhaps the most practical method for connecting peripherals ever conceived for a computer system. The number of devices that use USB has grown tremendously since its initial implementation almost anything you want to connect to a PC is available in USB versions and many items are only available in USB. USB, however, is not foolproof BIOS, USB chipsets, adequate power supply, proper cabling, and well-designed software device drivers must all work together to provide that true Plug and Play experience for everything from PDAs to video cameras and MP3 players. USB devices themselves do not often fail, so it is important to verify all of the elements that allow USB to work. The examples above are very common and reliable methods to ensure your USB devices works with your computer.

See Also

Comprehensive information about how USB works with Windows XP may be found at http://www.microsoft.com/whdc/system/bus/USB/default.mspx. A general overview of USB features and functions may be found at http://www.microsoft.com/windowsxp/using/networking/learnmore/jones_02august05.mspx.