The spec talks in terms of voltage levels being used to indicate charging current requirements.

How the implementor achieves those voltage levels is entirely up to them.   That Apple chose those particular values in a resistor network comprising a voltage divider is neither here nor there.   The spec is silent on how you do it, resistors, magic pixies, it doesn’t matter just so long as you comply.

There is nothing nefarious about this at all.   Your suggestion that there is, is simply a beat up.

According to the spec, DCP (dedicated charging port) must have D+ and D- shorted (well, 200 ohms). This is in fact true for nearly all non-apple phone devices. However, it does not work for iOS devices- & sprinkled throughout the spec are references to a mysterious ‘proprietary’ charger system that pulls D+/D- high which doesn’t match the D+/D- tie

Having read the the document a few times, it doesn’t seem clear where the spec mentions the Apple-specific 49.9K/75K resistor divider (those values are official Apple spec but that spec is under NDA). Can you help me find it & email support@adafruit.com? Very interested in any insight you can give that the USB charging spec discusses Apple’s ‘proprietary’ technique in detail :)

You have to read the whole thing carefully (and it took me about 2 days to realise that ladyada had completely missed this stuff)

Basically it says that various voltage levels are used to detect the current requirements of the attached device.   Those voltage levels are set by the so-called “secret resistors”.

In fact ladyada *knows* that’s what those resistors do, she just doesn’t realise that they’re part of the standard.   Instead she does some reverse engineering, discovers how the trick is done but then goes off the rails and says Apple is doing something “secret”.   They’re not.

What we’re looking at in the case of Apple is simply good engineering in line with standards.   Nothing nefarious at all.

No woo-woo here, move along.

Two cases in point:

1.  The MintyBoost has serious problems as a charger, sure it’s a cute use of a current thief circuit but LadyAda doesn’t seem to understand impedences.

2.  She did a scathing report on so-called nefarious “secret resisters” used by Apple in its charging via USB circuit.   Rot.   Those resistors are necessary to make the USB interface conform to the USB electrical standard.   She either doesn’t understand that, or is doing a beat up.

Good entrepreneur.   Not to be taken too seriously on technical matters.

I guess a 10 mil in rev counts as a business now?

Happy Days!!!! :D