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Don Parsons wrote:
Since there has been a lot of discussion here about using external GPS with an iPad for navigation, I thought I would pass this along.....
I find the attachment to your e-mail very hard to believe. The USB spec requires a hub to provide at least 100mA on every port. When a device is connected to a hub, it can draw up to 100mA without asking any permission. It then has to request permission to draw more current, up to 500mA for a basic system and more from higher current hubs. The hub is under no obligation to grant permission and the device is under no obligation to work if the permission is not granted.
If a hub is truly limiting the current to 20mA, it is in violation of USB specs as well as the USB logo licensing agreement. More importantly, for this to be the case, Apple must have incorporated some really custom hardware to physically limit the current to an arbitrary 20mA. Custom hardware costs more money than standard stuff and it is not something they would do lightly.
If the new OS was limiting everyone to 100mA, then a lot of devices would stop working. But devices like keyboards and microphones usually draw less then a100mA and should not be impacted. I can not imagine a microphone taking even 20mA. I think it is far more likely that there is a plain old bug in the OS that is preventing USB devices from working. Microsoft does not have monopoly on bugs!
I agree with the suggestion to test before going to the airport and to thoroughly research before upgrading the OS or any other software.
Regards,
Hamid
Now hopefully this issue is limited to USB through the iPad Camera Kit USB adapter. If this USB power issue is limited to that device, this should not effect your Bad Elf GPS. But if you are using another external GPS through USB with a Camera Kit adapter, I would expect that your GPS would be in an under powered state. Whatever external GPS you are using, if it depends on power from the iPad, I would test it. You also might want to check first before upgrading to 4.2.1 first if you have not yet upgraded.
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Don Parsons
Sent from an iPhone 4
Begin forwarded message:
*Subject:* *iOS 4.2 said to be blocking iPad Camera Kit from supporting some USB devices*
<http://www.engadget.com/2010/12/06/ios-4-2-said-to-blocking-ipad-camera-kit-from-supporting-some-us/>It seems that folks hoping for the Apple's Camera Connection Kit <http://www.engadget.com/2010/03/29/ipad-camera-connection-kit-finally-surfaces-for-pre-order-still/> to solve all their USB-related iPad problems just can't catch a break. First the kit was nearly impossible to find <http://www.engadget.com/2010/06/02/ipad-camera-connection-kit-a-commodity-item-now-fetches-100-o/>, and now we're seeing a slew of user reports saying that iOS 4.2 has made the USB portion of the camera kit nearly useless for many USB devices that were previously supported. As /9 to 5 Mac/ reports, the problem seems to boil down to the amount of power that can be emitted from the iPad's 30-pin connector -- it used to be 100mA, but iOS 4.2 appears to have cut that down to just 20mA, presumably in an attempt to conserve battery life. The big issue there, of course, is that everything from USB keyboards to microphones and even some cameras no longer work, and there isn't much for users left to do other than to hope that Apple brings back support in a future update. Feel free to share your own tales of woe in comments, or let us know if you're having problems with the iPad camera kit.
iOS 4.2 said to be blocking iPad Camera Kit from supporting some USB devices <http://www.engadget.com/2010/12/06/ios-4-2-said-to-blocking-ipad-camera-kit-from-supporting-some-us/> originally appeared on Engadget <http://www.engadget.com> on Mon, 06 Dec 2010 12:59:00 EDT. Please see our terms for use of feeds <http://www.weblogsinc.com/feed-terms/>.
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Don Parsons
Sent from an iPhone 4
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