On 5/13/10 10:45 PM, Stephen Conrad wrote:
On Thu, May 13, 2010 at 10:57 PM, Clark Martin <cm...@sonic.net <mailto:cm...@sonic.net>> wrote:On 5/13/10 1:34 PM, Bruce Johnson wrote: On May 13, 2010, at 12:32 PM, Kris Tilford wrote: What could have changed? The battery is lower on charge, and is drawing more amperage than before. The limit is 500mA total per USB port unless you have an external USB hub with its own power supply. I've seen this message before using a USB memory stick to a keyboard port. Since the USB memory stick doesn't draw significant power, this might be an error specific to keyboard ports that you can safely ignore, at least that's what I did. Also the Mac keyboard ports are lower power than normal, because they're an unpowered hub. I've seen some older USB flash drives produce that warning. There is a maximum of 500mA available from a powered port (on the computer or a powered hub). Each device is allocated a minimum of 100mA. The hub inside the keyboard, the keyboard itself, the mouse and the camera are likely each requesting the minimum of 100mA so that's a total of 400 mA allocated. That leaves 100mA still available so this problem SHOULDN'T be happening. If the keyboard is plugged into an unpowered hub you could get this problem. USB is in many ways a well thought out specifications but the implementation frequently falls short. I have seen some USB devices that request 500mA regardless of what they need. I suspect the programmers were just being lazy. OK, here is what Apple System Profiler says The Second USB Hub is powered off a power cord while the first is powered by the USB Bus
There's your problem. You have the keyboard running off the bus powered hub. You should have the keyboard plugged into a either an externally powered hub or the computer. Best bet is to be connected directly to the computer.
*USB Bus:* Host Controller Location: Built In USB Host Controller Driver: AppleUSBOHCI PCI Device ID: 0x0019 PCI Revision ID: 0x0001 PCI Vendor ID: 0x106b Bus Number: 0x18 *Hub in Apple USB Keyboard:* Version: 2.10 Bus Power (mA): 500 Speed: Up to 12 Mb/sec Manufacturer: Alps Electric Product ID: 0x1001 Vendor ID: 0x05ac (Apple Computer, Inc.) *USB-PS/2 Optical Mouse:* Version: 27.20 Bus Power (mA): 100 Speed: Up to 1.5 Mb/sec Manufacturer: Logitech Product ID: 0xc044 Vendor ID: 0x046d *Apple USB Keyboard:* Version: 1.02 Bus Power (mA): 250 Speed: Up to 1.5 Mb/sec Manufacturer: Alps Electric Product ID: 0x0201 Vendor ID: 0x05ac (Apple Computer, Inc.)
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