Quote:
Originally Posted by CubicleGeek
So explain this. Why can't this "chip" and signal conversion exist in the device? All it is doing is interpreting whether the signal coming in on any pin is power, audio, usb, etc, why can't that interpretation be done at the connector on the phone and needs to be interpreted by the cable? The chip exists in that white jacket right before the male connector you plug into the phone itself.
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Good question - the answer is that placing the chip outboard of the phone means you can have outputs supporting any arbitrary number of pins. If the chip was internal to the phone, and the output you wanted exceeded 16 pins, you'd need to use a larger connector. HDMI as an example, is a 19 pin connector. So if you had the chip on board, you'd need an output connector built into the phone that had 19 pins, since you've got to support the full spec. To support legacy iPod interface connections, as another example, you'd need 30 pins, and at that point, you're right back where you started - with an oversized, physically weaker, and more failure prone connection.
Chip in the cable means you can handle any legacy, current technology, or future connectivity requirement without having to change the connector on the phone, since the phone only needs to know how to talk Lightning via 16 pins. No more, no less, irrespective of what the outboard connectivity looks like.
At a protocol level, rather than just a pin out electrical level, it's even more complicated than this - because you only have 16 pins of output capability, the devices themselves are not actually capable of providing full spec output - instead, they deliver an I/O stream that is generalized to the type of data being handled, and let the cable handle the implementation details. So in our HDMI example, since the iPhone only has 16 pins out, rather than attempt to deliver HDMI down the cable, it actually AirPlay's an MPEG data stream to the cable, and the chip in the cable (which is a full on System on a Chip (SOC), by the way), receives that Airplay stream, and encodes it into full spec HDMI out.
In effect, iOS devices only need to know how to "speak" a few simple data formats - audio, video, and binary data. They don't even need a USB controller on board, since that translation is handled on the cable. Apple could introduce a USB3 compatible lightning cable, and you'd never need to upgrade to an iOS device with a USB3 controller on board - it would "just work" at USB3 speeds.
So the engineering beauty of the Lightning connector is two-fold. First, at a physical level, it decouples the number of pins required between input and output devices, ensuring a single, consistent physical interface across all iOS devices. Second, it decouples the protocols and signalling formats the phone needs to know how to speak - the phone needs none of the signalling logic required for multiple protocols, since it just speaks high speed digital data to the cable, and lets it do all the protocol conversion and I/O signalling.