Quote:
Originally Posted by sk2003
Another weird bug to report on 4.4.9344: charging the Kobo Aura HD with an Apple adapter causes the "connect to computer" dialogue to pop up. Doesn't pop up when charging it via a generic USB hub... what's going on, Kobo?
Don't have this issue on my Kobo Aura H2O with 3.19 installed.
|
The methods for informing the device that a charger and not a computer are connected are not very standard for USB 2. Two of the most common are Apple which uses specific resistors on the data pins to set the current from the charger (in one charger I dismantled, there were two voltage dividers, one was +5V-43K-|-51K-gnd connected to the data+ pin while the other was +5V-75K-|-51K-gnd connected to the data- pin allowing a 1A charging rate). The other common technique is to simply to short the two data pins with no other connection (floating) often referred to as the China standard. Sony used the same voltage divider technique as Apple but with different resistors in the dividers. Then we add in the USB Battery Charging specifications 1.2 and it's added fillips.
The problem is that depending on the design of your charger, you can have any of the above or yet another method to specify that a charger is connected and what charging current is supported. Mix this with the chip on the device that is attempting to detect what is connected and confusion is pretty much guaranteed.