Quote:
Originally Posted by DaleDe
The Pocket Pro has a standard AC charger included with the device. It provides a standard way to power and charge the device via the USB connector, also supplied.
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Standard for the device, maybe, but not standard for USB. There are a handful of ways in which the USB client port can detect that a power source is connected rather than a USB host. I was actually unaware that there is now an endorsed method of charging until I went looking as a result of the comments here.
Since it does include an adapter, it is likely that the device will charge, and be powered by, the adapter in all cases. The BeBook comment above would seem to confirm this.
Quote:
Originally Posted by Dave_S
It seems that you just described a Catch-22 situation for devices that are solely powered by USB, like keyboards and mice? While negotiation with the computer for power requirements is possible, with no negotiation the device will receive the default full power of 500 ma.
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It is actually the opposite: the device must draw the minimum until negotiated for more. This generally means 2.5mA (unconnected), 100mA (connected but not negotiated for more), or 500mA negotiation.
Quote:
Originally Posted by Dave_S
That is how USB powered lights and fans receive power from a USB port with no microcontroller involved at all.
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They draw power by taking advantage of the fact that it is difficult (and not entirely necessary) to dynamically limit the current available the the port. As I recently learned, though, the Battery Charging Specification changes the rules slightly.
Quote:
Originally Posted by jusmee
The are 4 wires. Two for power, 2 for data. It is perfectly possible to use the power wires without any computer connected to the data wires.
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Exactly. Although generally against the specification, it is difficult to prevent me from building my USB-powered toothbrush and abusing the USB port.