MacRumors pointed us today to an analysis of Apple’s new Lightning connector from developer Rainer Brockerhoff. There was some controversy surrounding Apple’s decision to go with the new connector, but Brockerhoff outlined some of the benefits of the Lightning connector’s all-digital, adaptive interface, including its ability to detect and adapt to connecting devices:
-Lightning is adaptive.
-All 8 pins are used for signals, and all or most can be switched to be used for power.
-The outer plug shell is used as ground reference and connected to the device shell.
-At least one (probably at most two) of the pins is used for detecting what sort of plug is plugged in.
-All plugs have to contain a controller/driver chip to implement the “adaptive” thing.
-The device watches for a momentary short on all pins (by the leading edge of the plug) to detect plug insertion/removal.
-The pins on the plug are deactivated until after the plug is fully inserted, when a wake-up signal on one of the pins cues the chip inside the plug. This avoids any shorting hazard while the plug isn’t inside the connector.
-The controller/driver chip tells the device what type it is, and for cases like the Lightning-to-USB cable whether a charger (that sends power) or a device (that needs power) is on the other end.
-The device can then switch the other pins between the SoC’s data lines or the power circuitry, as needed in each case.
-Once everything is properly set up, the controller/driver chip gets digital signals from the SoC and converts them – via serial/parallel, ADC/DAC, differential drivers or whatever – to whatever is needed by the interface on the other end of the adapter or cable. It could even re-encode these signals to some other format to use fewer wires, gain noise-immunity or whatever, and re-decode them on the other end; it’s all flexible. It could even convert to optical.
What exactly does this mean for all of those third-party manufactures that might not have anticipated the technology Apple is putting into the new connector? Speaking to Gizmodo, Peter from Double Helix Cables explained the chip Apple is using inside the connector will make it very difficult to reverse engineer. In other words, it’s quite possible the many third-party adapters and cables already being advertised don’t actually function as a Lightning connector:
It remains to be seen whether the chip can be reverse engineered. Nobody that I know of managed to crack the MFi program before, since digital Apple docks and other MFi certified stuff were always quite costly and only coming from well established name brands that participated in the program. I never saw any off brand, super cheap version of the iPod USB digital audio interfaces that cost hundreds of dollars. If the chip has some code on board that makes it authenticate with the iPhone, then it may be hard to duplicate for sure. If it’s doing a “smart” function like pin assignment or something crazy like that, then it definitely is going to be mandatory. Apple has said it’s a “smart” connector but it is horrifying that just a basic power charging/sync cord like this requires additional complexity. But until some serious engineers figure out exactly what the chips do (MFi people are under NDA so I don’t think they can tell us without breaking NDA) then it remains open for debate why this cable is like this.
You can read more of Brockerhoff’s in-depth analysis on his blog.