2013-01-15, 02:20
Both the articles below recommend powered hubs.
USB 2.0, Hi-Speed USB FAQ
..."A powered hub is always preferable to unpowered."
..."Many USB devices don't work well on hubs. Cameras, scanners and especially USB drives are known to have problems with hub connectivity."
..."How does a USB hub slow down devices?
A USB hub has to re-calculate the time left before the next sof (end of the uframe); the small extra delay added by the hardware hub could make the transaction not handled as fast as a device directly connected to the host. If several devices are connected on the USB hub and working in parallel (for example, a webcam + a USB flash drive + a mouse), then the USB bandwidth is shared among the devices usage."
Adding USB Drives to a Raspberry Pi
"In order to expand storage capacity, you will need to connect a powered USB hub to one of your Pi USB jacks, and then connect the keyboard, mouse/trackpad (if any), and USB drive to the hub."
1) Sometimes this Logitech Wireless Touch Keyboard K400 works after power up and other times I have to unplug rPi one or more times to get it to see it again. Luckily I have xbmc on a USB stick to avoid corruption, which I learned the hard way. Could this be because I'm not using a powered hub? Is anyone else using this same keyboard with same issue? Anyone have an idea on how to remedy?
2) Will the speed of the USB stick (xbmc processes) be better off using a power hub?
3) BTW, does the size of the USB stick used for xbmc effect speed?
4) Are the USB ports on the rPi full or high speed?
USB 2.0, Hi-Speed USB FAQ
..."A powered hub is always preferable to unpowered."
..."Many USB devices don't work well on hubs. Cameras, scanners and especially USB drives are known to have problems with hub connectivity."
..."How does a USB hub slow down devices?
A USB hub has to re-calculate the time left before the next sof (end of the uframe); the small extra delay added by the hardware hub could make the transaction not handled as fast as a device directly connected to the host. If several devices are connected on the USB hub and working in parallel (for example, a webcam + a USB flash drive + a mouse), then the USB bandwidth is shared among the devices usage."
Adding USB Drives to a Raspberry Pi
"In order to expand storage capacity, you will need to connect a powered USB hub to one of your Pi USB jacks, and then connect the keyboard, mouse/trackpad (if any), and USB drive to the hub."
1) Sometimes this Logitech Wireless Touch Keyboard K400 works after power up and other times I have to unplug rPi one or more times to get it to see it again. Luckily I have xbmc on a USB stick to avoid corruption, which I learned the hard way. Could this be because I'm not using a powered hub? Is anyone else using this same keyboard with same issue? Anyone have an idea on how to remedy?
2) Will the speed of the USB stick (xbmc processes) be better off using a power hub?
3) BTW, does the size of the USB stick used for xbmc effect speed?
4) Are the USB ports on the rPi full or high speed?