Alex, I am not an expert, but ADK assumes that the accessory takes the role of USB HOST on the bus Android <---> Accessory. This according to USB standard has very specific power implications, including provision of power to devices connected to USB bus.
Host provides the power, while client drains it. I am not aware of a phone that can act as USB HOST (i.e. charging other devices hanging of its USB port) and presumably this is to always protect the battery. USB Accessory for Android talks only about communication and it is a high level standard (no power control from the SDK), which *could* mean that the standard simply assumes that phone always gets charged from the host at the host's full charging capacity (500mA, 5.5V) HTH, Daniel On 13 January 2012 15:15, Alex O. <alex.c.olte...@gmail.com> wrote: > Hello, > > Let me rephrase my question. If I understand this correctly, an > accessory must have its own power source and, moreover, should also > provide power to the phone (500mA at 5V for charging power). > > In this case, it seems that the accesories can only be bulky devices > (such as the Arduino board in ADK) with charging cables and no form > factor constraints. Or, perhaps, augmentations to extra-battery packs. > > 1) Is this the scope of the Open Accessory, or am I missing the point? > 2) Is there any way that, at least, the accessory should provide its > own power, but not have to power the phone as well? > > Best regards, > Alex > > > > On Jan 8, 10:27 am, "Alex O." <alex.c.olte...@gmail.com> wrote: >> Hi all, >> >> We are interested in developing an USB dongle for Android devices. We >> consider implementing the Open Accessory protocol for the dongle, so >> it would work with both tablets and phones, without changes in the >> kernel for the Android device. >> >> However, if I understand this correctly, the dongle would need to have >> its own power source and provide 500mA at 5V for charging power. Is >> there any way to make this dongle without its own power source? >> >> Thank you,Alex > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to android-developers@googlegroups.com > To unsubscribe from this group, send email to > android-developers+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en -- Daniel Drozdzewski -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to android-developers@googlegroups.com To unsubscribe from this group, send email to android-developers+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
