@lightsoff said:IIRC, Apple chargers used to have proprietary resistor nets that their devices measured, in order to make sure you only buy Apple chargers
Apple and other USB charger secrets |
Apple chargers is simple: just few resistors. If you don’t put these secret resistors on the data lines too, you get the dreaded Charging is not supported with this accessory.
@lightsoff said:They now have a data handshake between the device, charger and cable as well
Not sure it's a handshake, but it does involve the data lines: http://apcmag.com/android-usb-charging-secrets.htm/
[Apple] decided that if an iPhone or iPad came up against a USB port with 2.0VDC on the D+ line and 2.7VDC on the D- line, that port would be an Apple iPhone (DCP) charger that could supply 1000mA of current. If the voltages were reverse (2.7V/2.0V on the D+/D- lines), it’d be an iPad charger with 2000mA maximum supply.