Boom: Pins

September 23, 2012 at 20:19:54 Rainer Brockerhoff 46 comments

This post has been updated several times (last update was on Feb.8, 2013); be sure to scroll to the end. Also see my final follow-up in 2014.

One central feature of any connector/plug is the pincount. The ubiquitous AC plugs we all know from an early age have 2 (or, more usually, 3) easily visible pins and of course the AC outlet is supposed to have the same number – and, intuitively, we know that the cable itself has the same number of wires. Depending on where you live, you may also be intimately familiar with adapters or conversion cables that have one type of plug on one end and a different type on the other. Here’s one AC adapter we’ve become used to here in Brazil, after the recent (and disastrous) change to the standard:

Even with such a simple adapter – if you open it, there’s just three metal strips connecting one side to the other – mistakes can be made. This specific brand’s design is faulty, assuming that the two AC pins are interchangeable. This is true for 220V, but in an area where 110V is used, neutral and hot pins will be reversed, which can be dangerous if you plug an older 3-pin appliance into such an adapter.

Still, my point here is that everybody is used to cables and adapters that are simple, inexpensive, and consist just of wires leading from one end to the other – after all, this is true for USB, Ethernet, FireWire, and so forth. Even things like DVI-VGA adapters seem to follow this pattern. But things have been getting more complicated lately. Even HDMI cables, which have no active components anywhere, transmit data at such speeds that careful shielding is necessary, and cable prices have stayed relatively high; if you get a cheap cable, you may find out that it doesn’t work well (or at all).

The recent Thunderbolt cables show the new trend. Thunderbolt has two full-duplex 10Gbps data paths and a low-speed control path. This means that you need two high-speed driver chips on each end of the cable (one next to the connector, one in the plug). This means that these cables sell in the $50 price range, and it will take a long time for prices to drop even slightly.

DisplayPort is an interesting case; it has 1-4 data paths that can run at 1.3 to 4.3Gbps, and a control path. The original connector had limited adoption and when Apple came out with their smaller mini version, it was quickly incorporated into the standard, and also reused for Thunderbolt. An even smaller version, called MyDP, is due soon. Analogix recently came out with an implementation of MyDP which they call SlimPort. MyDP is intended for mobile devices and squeezes one of the high-speed paths and the control paths down to 5 pins, allowing it to use a 5-pin micro-USB connector. Here’s a diagram of the architecture on the device side:

If you read the documentation carefully, right inside the micro-USB plug you need a special converter chip which converts those 3 signals to HDMI, and from then on, up to the other end of the cable, you have shielded HDMI wire pairs and a HDMI connector. Of course, this means that you can’t judge that cable by the 5 pins on one end, nor can you say that that specific implementation “transmits audio/video over USB”. It just repurposes the connector. Such a cable would, of course, be significantly more expensive to manufacture than the usual “wires all the way down” cable, and (because of the chip) even more than a standard HDMI cable.

Still referring to the diagram above, if you substitute the blue box (DisplayPort Transmitter) for another labeled “MHL Transmitter”, you have the MHL architecture, although some implementations use an 11-pin connector. Common to both MHL and MyDP is the need for an additional transmitter (driver) chip as well as a switcher chip that goes back and forth between that and the USB transceivers. This, of course, implies additional space on the device board for these chips, traces and passive components, as well as increased power consumption. You can, of course, put in a micro-HDMI connector and drive that directly, that would save neither space nor power.

Is there another way to transmit audio/video over a standard USB implementation? There are device classes for that, but they’re mostly capable of low-bandwidth applications like webcams; at least for USB2. Ah, but what of USB3? That has serious bandwidth (5Gbps) that certainly can accommodate large-screen, quality video, as well as general high-speed data transfer – not up to Thunderbolt speeds, though. You need a USB3 transceiver chip in the blue box above, and no switcher chip; USB3 already has a dedicated pin pair for legacy USB2 compatibility. All that’s needed is the necessary bandwidth on the device itself; and here’s where things start to get complicated again.

You see, there’s serious optimization already going on between the processor and display controller – in fact, all that is on a single chip, the SoC (System-on-a-Chip), labelled A6 in the iFixit teardown. Generating video signals in some standard mode and pulling it out of the SoC needs only a few added pins. If you go the extra trouble to also incorporate a USB3 driver on the SoC and a fast buffer RAM to handle burst transfers of data packets, the SoC can certainly implement the USB3 protocols. But – and that’s the problem – unlike video, that data doesn’t come at predictable times from predictable places. USB requires software to handle the various protocol layers, and between that and the necessity to, at some point, read or write that data to and from Flash memory, you run into speed limits which make it unlikely that full USB3 speeds can be handled by current implementations.

But, even so, let’s assume, for the sake of argument, that the A6 does implement all this and that both it and the Flash memory can manage USB3 speeds. Will, then, a Lightning-to-USB3 cable come out soon? Is that even possible? (You probably were wondering when I would get around to mentioning Lightning…)

Here’s where the old “wires-all-the-way-down” reflexes kick in, at least if you’re not a hardware engineer. To quote from that link:

Although it’s clear at this point that the iPhone 5 only sports USB 2.0 speeds, initial discussions of Lightning’s support of USB 3.0 have focused on its pin count—the USB “Super Speed” 3.0 spec requires nine pins to function, and Lightning connectors only have eight.

…The Lightning connector itself has two divots on either side for retention, but these extra electrical connections in the receptacle could possibly be used as a ground return, which would bring the number of Lightning pins to the same count as that of USB 3.0—nine total.

(…followed, in the comments, by discussions of shields and ground returns and…)

Of course, that contains the following failed assumptions (beyond what I just mentioned):

Lightning is just a USB3 interface in disguise, and
Cables and connectors are always wired straight-through, at most with a shield around the cable.
If there are any chips in the connector, they must be sinister authentication chips!

These assumptions also underlie the oft-cited intention of “waiting for the $1 cables/adapters”. But, recall that Apple specifically said that Lightning is an all-digital, adaptive interface. USB3 is not adaptive, although it can be called digital in that it has two digital signal paths implemented as differential pairs. If you abandon assumptions 1 and 2, assumption 3 becomes just silly. Remember, the SlimPort designers put a few simple digital signals on the connector and converted them – just a cm or so away – into another standards’ differential wire pairs by putting a chip inside the plug.

So, summing up all I said here and in my previous posts:

Lightning is adaptive.
All 8 pins are used for signals, and all or most can be switched to be used for power. So it makes no sense to say “Lightning is USB2-only” or whatever. (But see update#5, below.)
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. (This has apparently been disproved by some cheap third-party plugs that don’t have a metal leading edge.)
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.

I’ll be seriously surprised if even one of those points is not verified when the specs come out. And this is what is meant by “future-proof”. Re-using USB and micro-USB (or any existing standard) could never do any of that.

Update: just saw this article which purports to show the pinouts of the current Lightning-to-USB2 cable. “…dynamically assigns pins to allow for reversible use” is of course obvious, if you put together the “adaptive” and “reversible” points from this picture of the iPhone 5 event. Regarding the pinout they published, it’s not radially symmetrical as I thought it would be (except for ~~one~~ two pins), so I really would like a confirmation from some site like iFixit (I hear they’ll do a teardown soon). They also say:

Dynamic pin assignment performed by the iPhone 5 could also help explain the inclusion of authentication chips within Lighting cables. The chip is located between the V+ contact of the USB and the power pin of the Lightning plug.

I really see no justification for the “authentication chip” hypothesis, and even their diagram doesn’t show any single “power pin of the Lightning plug”. It’s clear that, once the cable’s type has been negotiated with the device, and the device has checked if there’s a charger, a peripheral or a computer on the other end, the power input from the USB side is switched to however many pins are required to carry the available current.

Update#2: I was alerted to this post, which states:

The iPhone 5 switches on by itself, even when the USB end [of the Lightning-to-USB cable] is not plugged in.

Hm. This would lend weight to my statement that a configuration protocol between device and Lightning plug runs just after plug-in – after all, such a protocol wouldn’t work with the device powered off. It also means that the protocol is implemented in software on the device side; otherwise they could just run it silently, until it really appears that the entire device needs to power up.

Still, there’s the question of what happens when the device battery is entirely discharged. I suppose there’s some sort of fallback circuit that allows the device to be powered up from the charger in that case.

Finally, I’ve just visited an Apple Store where I could get my first look at an iPhone 5. The plug is really very tiny but looks solid.

Update#3: yet another article reviving the authentication chip rumor. Recall how a similar flap about authentication chips in Apple’s headphone cables was finally put to rest? It’s the same thing; the chip in headphones simply implemented Apple’s signalling protocol to control iPods from the headphone cable controls. The chip in the Lightning connector simply implements Apple’s connector recognition protocol and switches charging/supply current.

Apple is building these chips in quantity for their own use and will probably make them available to qualified MFi program participants at cost – after all, it’s in their interest to make accessories widely available, not “restrain availability”.

Now, we hear that “only Apple-approved manufacturing facilities will be allowed to produce Lightning connector accessories”. That makes sense in that manufacturing tolerances on the new connector seem to be very tight and critical. Apple certainly wouldn’t want cheap knock-offs of the connector causing shorts, seating loosely or implementing the recognition protocol in a wrong way; this would reflect badly on the devices themselves, just as with apps. Think of this as the App Store for accessory manufacturers. 🙂

Update#4: new articles have come out with more information, confirming my reasoning.

The folks at Chipworks has done a more professional teardown, revealing that the connector contains, as expected, a couple of power-switching/regulating chips, as well as a previously unknown TI BQ2025 chip, which appears to contain a small amount of EPROM and implements some additional logic, power-switching, and TI’s SDQ serial signalling interface. SDQ also uses CRC checking on the message packets, so a CRC generator would be on the chip. Somewhat confusingly, Chipworks refer to CRC as a “security feature”, perhaps trying to tie into the authentication angle, but of course any serial protocol has some sort of CRC checking just to discard packets corrupted by noise.

Anandtech has additional information:

Apple calls Lightning an “adaptive” interface, and what this really means are different connectors with different chips inside for negotiating appropriate I/O from the host device. The way this works is that Apple sells MFi members Lightning connectors which they build into their device, and at present those come in 4 different signaling configurations with 2 physical models. There’s USB Host, USB Device, Serial, and charging only modes, and both a cable and dock variant with a metal support bracket, for a grand total of 8 different Lightning connector SKUs to choose from.

…Thus, the connector chip inside isn’t so much an “authenticator” but rather a negotiation aide to signal what is required from the host device.

Finally, there’s the iFixit iPod Nano 7th-gen teardown. What’s important here is that this is the thinnest device so far that uses Lightning, and it’s just 5.4mm (0.21″) thick. From the pictures you can see that devices can’t get much thinner without the connector thickness becoming the limiting factor.

Update#5: the Wikipedia article now shows a supposedly definite pin-out (and the iFixit iPhone 5 teardown links to that). Although I can’t find an independent source for the pin-out, it shows two identification pins, two differential data lanes, and a fixed power pin. Should this be confirmed it would mean that the connector is less adaptive in regarding to switching data and power pins; on the other hand, that pinout may well be just an indication of the default configuration for USB-type cables (that is, after the chips have negotiated the connection).

Apple, Hardware iPad, iPhone

Comments (46)

#1 | Written by Dominic on March 12, 2013.

Quite a lot of information there. Thanks for the effort.
#2 | Written by red on March 2, 2013.

@ Rainer @41
Strictly speaking all signals are analog.

The encoded information can be digital or analog but all signals are analog in nature on our macro level.
In case of these differential signals they encode bits just as much as a non-differential signal. The only difference is that in the normal case the signal balances around a fixed potential and in the differential case the signal balances against it’s antipotential.
It is just a trick for reducing outside interference.
#3 | Written by Rainer Brockerhoff on January 2, 2013.

@rva, no further details have been published about the protocol or the chips. I wouldn’t count “charging” as a protocol, though.
#4 | Written by Rva on January 1, 2013.

Hi, nice article. I found this cable idea very attractive. I like to have things universal. I am busy with mcu’s and try to use any connection this way to avoid fat cables and clutter and save pins on the chips and cables. The only thing here is what if I want to use two/three protocols at the same time? Charging, using usb data transfer and watching something over hdmi? Will it savely switch fast enough?

A question, what about a serial protocol, like on the old iDevices? It is in there? Do I need a different lightning chipset? Do you know anything about that?
Thank you.
#5 | Written by Rainer Brockerhoff on October 18, 2012.

@Howard, re #1: suppose you allowed a “dumb” charging cable. It would have the 5 VDC permanently exposed on the open plug (and on both sides!) so if it brushes against some sort of metal object you’d have a nice short circuit. That’s why the plug has power-switching circuitry.
re #3: right, all pictures show contacts on one side only. Putting contacts on both sides in a future device would introduce incompatibilities and make the connector side too thick – the iPod nano teardown I linked to shows that this is already one of the factors limiting device thinness.
#6 | Written by Howard M on October 17, 2012.

Thanks for a comprehensive analysis. Nice to get some clarity 🙂

A few things though:

1) You’re right, ‘authentication chip’ is a misnomer – there’s no way to provide all the connectivity required from 8 connections without needing some intelligence on the outside too. I’m still, however, struggling to understand why there couldn’t be some simple dumb-cable fallback option provided – as other commenters here have suggested.

Even just plain ‘ole USB2 – only 4 conductors required; surely the controller in the phone (which will have sensibly disconnected all the internal connections when it sensed a plug being inserted) could detect a ‘dumb’ cable, check if there was 5v present on a certain pin, and if so it could pass the appropriate signals to the right pins? This seems like a software thing to me, not hardware.

“If communications with the lightning chip in the newly-inserted cable fail, and there’s 5 volts on pin 1, go into USB/charge mode”.

2) Note that the maximum power an iDevice may need from a charger is now up to 2A; the newer iPads (if they detect the right voltages on D+ and D-, ie they recognise a capable charger) will suck up 10 watts when they’re in bulk absorption mode, usually when charging from 10-90% of capacity.

This is probably a bit much for a single connection on the lightning connector, hence the need to employ more than one pin for charging. (Again, though, this doesn’t mean a ‘dumb cable fallback’ facility wouldn’t work – just assign more pins to power and ground)

3) The whole “reversible” plug thing – although the pads on top and bottom of the new plug are connected together internally on the cables we’ve seen so far, meaning you couldn’t pass 16 separate signals down it, there’s no reason that future iDevices with larger charge current requirements couldn’t employ a socket that had contacts at top and bottom to double up. Speaking of which, I take it someone’s looked at the sockets and checked whether there are only contacts on one side?

4) Really looking forward to someone getting a buspirate or scope on one of these things so we can see a bit more of what’s going on protocol-wise. It’d be nice to think we’ll be adding Lightning connectors to Arduino projects if we wanted… 🙂
#7 | Written by doubleyou on October 16, 2012.

@Rainer
you may want to update your blog post with the information given here: http://www.chipworks.com/blog/recentteardowns/2012/10/15/inside-the-apple-lightning-cable/
For me the BQ2025 is a simple EPROM that tells the host (e.g. iPhone5) of the lightning connector via SDQ how to configure it’s adaptive pins and what protocol is needed to drive these pins; like USB, I2S for an audio DAC, HDMI for video out etc.
#8 | Written by someone on October 7, 2012.

“That makes sense in that manufacturing tolerances on the new connector seem to be very tight and critical. Apple certainly wouldn’t want cheap knock-offs of the connector causing shorts, seating loosely or implementing the recognition protocol in a wrong way; this would reflect badly on the devices themselves, just as with apps.

Is the cable (disregarding the chip) a simple, easy to manufacture cable? Yes. Please explain why the currently relevant USB-Lightning cable manufacturing tolerances are somehow more critical than with a normal Micro USB cable?

Will having the chip prevent manufacturing of ‘fake’ cables without (or with faulty) chip? No. So how does the chip save us from those shorts (Is this a problem with USB? No.) and loosely fitting cables?

“Think of this as the App Store for accessory manufacturers. :-)””

Think of this as the DRM for accessory manufacturers. 🙂

In fact, if they were to release the full specs, we would get fewer badly fitting non-working cables from third party manufacturers, not more…
#9 | Written by Rainer Brockerhoff on October 5, 2012.

@someone, see update#3 above for my comment on this.
#10 | Written by someone on October 4, 2012.

“I really see no justification for the “authentication chip” hypothesis”

http://www.theverge.com/2012/10/3/3451032/apple-lightning-certification-accessory-restrictions

I do. It is probably not the only reason for the chip, but it certainly helps in limiting third-party implementations.
#11 | Written by Steve Weller on September 30, 2012.

Readers should familiarize themselves with Twisted Pair Ethernet (IEEE 802.3ab) and PoE, aka Power Over Ethernet (IEEE 802.3af-2003) and understand how with 8 pins you can get four signals going both ways at the same time (at 125 MHz), and transmit power from one end of the cable to the other, all the while maintaining isolation and performing negotiation for power and signal capability. Oh, and be able to dynamically adjust for pin reversal and some cabling errors.

Imagine a similar scheme being used by Apple.
#12 | Written by Chris Porter on September 26, 2012.

I’m tired of people whining and complaining about having to replace 8-12 cables they supposedly use throughout each day. I understand that it can be frustrating having to replace said cables but they are all a LUXURY or added convenience. I have cables at my desk at home, work, in my car, by the sound board at my church, in my wife’s car, 2 in my backpack, etc. It is very convenient that I have all those old 30-pin cables acquired from who knows where but they are NOT a necessity. I have myself an iPhone 5 and now I just have to actually stop and think if I’m going to be doing something today that would necessitate me bringing my cable along. Is that as convenient as before? Absolutely not. But is it so inconvenient that I need to go by cables…heck no! I’m sure I’ll break down and buy 1 or 2 sometime in the FAR feature but I definitely won’t be replacing them all because they aren’t NEEDED they’re wanted.

The only people that can somewhat complain are ones with installed setups in their automobiles and/or expensive sound docks (i.e. Bose/B&O) But even then Apple has a solution. Is it the most convenient…no…but it is the price you pay for wanting the latest greatest thing.

So, in conclusion people need to stop whining about how inconvenient their lives are now because they have to carry around a cable or put their money where their mouths are and just replace them.
#13 | Written by RF9 on September 26, 2012.

@Hamranhansenhansen
RE:
“People who are complaining about the cost of Lightning cables need to remember that most of your 30-pin connectors have already been replaced by AirPlay, Wi-Fi “n” and Wi-Fi Sync, and Bluetooth. You don’t necessarily need any Lightning cables other than what comes in the box. iPhone 5 also has LTE and Bluetooth 4 — much faster wireless — in addition to Lightning.”

Yes but you can’t charge, and the iPhone needs constant and frequent charges.
I have 1 at my desk at work. 1 in my laptop bag. 1 in my travel kit (so i don’t forget it it and because I don’t always bring the laptop bag.) 1 at my desk at home. 1 at the central charging area at home on the other side of the house. And 2, one in each car. Oh, and one on my night stand for overnight charging.
That’s 8 cables and chargers that I have in all areas I spent the most time that have power capabilities. I don’t like to have to remove a charger and take it with me. I want those chargers that are stationary to remain and the ones that go with me to stay in the bag.
Many of those cables and chargers I got cheap or got with previous iPhones or iPads and built up a collection.

So I’d be spending $140 on just cables just to replicate my setup. Or I’d have to keep 1 or 2 adapters with me to use on existing cables.

Is this necessary? No, but it sure is much more convenient in order to assure that my iPhone doesn’t run out of juice half way through the day.
I’d have voted Apple keep the thickness of the iPhone 4S and extend the battery life rather than make it a few mm thinner which functionally has not benefit to me.
I’m not complaining about the cost of the cables as they have some real tech in them. The old 30 pin were way overpriced because they were extremely cheap. At least you’re getting something for the price now.

I would like to see a cheaper charge-only cable and more expensive lightning cable. But it sounds like it’s not that simple.
#14 | Written by Rainer Brockerhoff on September 26, 2012.

@”Chris” (why disguise/omit your email?): “Any dedicated cable that Apple builds will be subject to a “man-in-the-middle” attack. And those dedicated cables won’t be future proof unless there is a way to do firmware updates”: no idea what “attack” could be made on a cable… firmware updates would mean the chip would be microprocessed, which I doubt for most normal interfaces. Anyway, it’s NOT the cables/adapters that are supposed to be future-proof, it’s the devices and the Lightning interface itself.
#15 | Written by Chris on September 26, 2012.

Any dedicated cable that Apple builds will be subject to a “man-in-the-middle” attack. And those dedicated cables won’t be future proof unless there is a way to do firmware updates (dramatically increasing the cost of production, btw).

This means that 3rd parties WILL be able to make dedicated cables for various purposes. I don’t think we’ll see general purpose cables, though… at least not until someone reverse engineers what the chip does.

But remember, Apple can’t upgrade old cables, so as long as they’re still supported, any 3rd party appliances will also work.

Now, the license fees for the connectors will be the key part of the tale.
#16 | Written by Rainer Brockerhoff on September 26, 2012.

@Scott: “A special base case of “wires all the way down”+ a few resistors, for the cheap seats”: remember the chip is always required to switch the power pin on, in the minimal case, even if it does no further signaling.
#17 | Written by Scott on September 26, 2012.

@RBrockerhoff @someone That was my thought, the idea that there is a “solid state” configuration (that wouldn’t require a “authentication chip”, or whatever it turns out to be) that basically triggers the adaptable Lightning port into a “standard basic USB cable” config that supports charging.

I’m not suggesting the port becomes non-adaptable, what I’m saying is cheap “hard-coded” USB cords would end-run the “anger”. A special base case of “wires all the way down”+ a few resistors, for the cheap seats. Why the Lightning port wouldn’t default to that mode now (at least for the time being) is really beyond me tho. Only require the “auth chip” for the special cables, with advanced capabilities beyond USB 2.
#18 | Written by Rainer Brockerhoff on September 25, 2012.

@someone: “While the interface hasn’t been recognized yet (as in, cable hasn’t been connected), what does it matter if two pins were reserved for this?” you’re right, that could be done. An analysis of the current cable will tell us much, should be out soon.
“One would expect that USB chargers were compatible with it, so 1A sounds a bit low.”: 1A is what the current iPhone/iPod adapters put out, as far as I know. I was judging purely by the picture of the contacts on iFixit.
#19 | Written by Rainer Brockerhoff on September 25, 2012.

@Emil: beyond the coincidences you mention, adopting PoE – and, therefore, Ethernet – would still be as inflexible as any other fixed interface.
#20 | Written by someone on September 25, 2012.

@Hamranhansenhansen: “Power going into the iPhone or out? Because there are many accessories that draw power from iPhone, while there are other accessories that put power into the iPhone. Is that going to be the same pin?”

My N8 with USB On-The-Go micro-USB port does not seem to have any problems with that. As a side note, which accessories draw power from iPhone (currently, pun not intended)? (I tried to find some)
#21 | Written by someone on September 25, 2012.

“except that, in that case, you’re dedicating two pins to “+/-” data lines”

Not really. Wasn’t the point that the connector is adaptable. While the interface hasn’t been recognized yet (as in, cable hasn’t been connected), what does it matter if two pins were reserved for this? If some other cable were to be connected, those lines could be used for something else.

“@Alan, from the look of the contacts inside the device, 1A per pin might be reasonable, and power depends on the voltage too.”

One would expect that USB chargers were compatible with it, so 1A sounds a bit low.
#22 | Written by Rainer Brockerhoff on September 25, 2012.

@Scott: “nothing … limits Apple from simply making USB/charging… work the same way the current USB/30-pin cables work: a fixed, predetermined resistance across the +/- data lines to set a basic functionality.” except that, in that case, you’re dedicating two pins to “+/-” data lines. But, I have no doubt this is what it works like on the USB end of Apple’s Lightning-to-USB cable. Saying that there are two fixed USB2 lines on the Lightning connector itself, again, goes back to the “straight wires” paradigm.
“I find it near incredible to think that Apple would believe they can force the millions of cheap-o cables that got sold up to a $30 Apple purchase.” Nope. The USB cables are $19, not $30. Once other manufacturers get up to speed I see nothing saying a basic Lightning-to-USB cable can’t be made and sold for the proverbial $9.99, and I bet that by the end of next year the price will be even lower.
“wait until iPhone 5 buyers learn they can no longer pickup a $9.95 car charger at Walmart or 5below!” now you’re talking about the charger, not Lightning. Any charger with a standard USB2 connector will go on working if you have a proper cable.
#23 | Written by Hamranhansenhansen on September 25, 2012.

> I doubt this one. Of course that would be technically possible, but massive data processing without charging does not sound sensible. Thus I would expect a pin to be reserved for charging. That would be more robust too.

Power going into the iPhone or out? Because there are many accessories that draw power from iPhone, while there are other accessories that put power into the iPhone. Is that going to be the same pin?
#24 | Written by Hamranhansenhansen on September 25, 2012.

People who are complaining about the cost of Lightning cables need to remember that most of your 30-pin connectors have already been replaced by AirPlay, Wi-Fi “n” and Wi-Fi Sync, and Bluetooth. You don’t necessarily need any Lightning cables other than what comes in the box. iPhone 5 also has LTE and Bluetooth 4 — much faster wireless — in addition to Lightning.
#25 | Written by Scott on September 25, 2012.

Regarding Apple’s “proprietary”-izing the connector, nothing in Mr. Brockerhoff’s post limits Apple from simply making USB/charging (the default use of most of these cables for most customers) work the same way the current USB/30-pin cables work: a fixed, predetermined resistance across the +/- data lines to set a basic functionality.

That isn’t to say, since the specs have not yet been released, that Apple hasn’t done this. I find it near incredible to think that Apple would believe they can force the millions of cheap-o cables that got sold up to a $30 Apple purchase. If you think the Maps app backlash has been crazy, wait until iPhone 5 buyers learn they can no longer pickup a $9.95 car charger at Walmart or 5below!

The fact that Apple’s cables are built a bit better is not evidence, in and of itself, of a lack of featureset. And the failure of the early cheapos to charge devices isn’t either. I’m hoping (as someone who has been an Apple Evangelist for a loooooong time and will have to hear the incessant griping) that the 3rd party, properly-designed-cable market will continue to exist.
#26 | Written by Emil on September 25, 2012.

Remember PoE? It’s 8 pin, delivers power and data and it’s reversible – auto mdi makes straight and cross-over interchangeable, PoE allows Power to be delivered on any pair up to 18 W (I think) and the power injectors can be made with passive components and data rates can go up to 10 Gbps over Cat6 cables at 100 meters. I imagine that shorter cables are less problematic. The only downside I see are the bulky transformers that are required to separate high frequency differential data signals from the DC current.
#27 | Written by Rainer Brockerhoff on September 25, 2012.

@ trrll, I think using the only side is impossible, as it would short out (or at the very least, become incompatible) with existing cables, and add more height to the connector, and hence to devices.
#28 | Written by Jeff B. on September 25, 2012.

Re: Hot vs. Neutral. There’s a very good reason for polarization and three prong plugs. All modern electrical panels are wired with a neutral bar and and ground bar. These are isolated from each other. One is the return path for the electrons coming back from the hot or line side. This is the neutral. The other is the equipment ground. This is a dedicated path to earth ground that acts as both a safety should something be faulty or become energized such as a metal case, and as a reference “zero” voltage. Also, and this is important, for returns from large draw appliances there is a significant difference in potential between the neutral and ground. And another critically important concept is that the safety protection, fuses, breakers, fuzed links, MOVs, GFCIs, etc. all operate on the Black wire/ Line side/ hot. If you switch polarity, you bypass all the safety. As such, when an appliance is properly wired, there will be a complete isolation of the line side/ hot, but the neutral can end up grounded in some poorly wired or legacy situations. Thus, it would very bad for the hot side be switched with the neutral, as then a case could become energized. This is a major cause of appliance fires. This is why amongst other things all new outlets are polarized and insurance companies like to see newer wiring in structures. However, there are some devices, without fusing, that do not have any polarity requirements. For example, your typical wall transformer that is sealed and disposable will simply have the line and neutral connected to the primary windings of a transformer in the case of linear supplies, and to the smaller transformer and switching circuitry in s switching supply. Here, there is no need to respect polarity, because there no user serviceable fuses, etc. and the transformer does not care which way the AC is connected.

Bottom line, even on old school cables that are just wires, polarity matters. Lightning is a great new adaptive interface that will serve Apple for many years to come and another great Apple innovation. All of the naysayers are simply ignorant of the implications. But buy now, everyone should know Apple very rarely does things for the wrong or bad reasons. Lightning is the future of cables, and people just don’t understand yet why they are really beneficiaries of Apple’s good work.
#29 | Written by trrll on September 25, 2012.

Given that the pins are dynamically assigned for reversibility, it does not necessarily even follow that the lightning interface is limited to 8 pins. Although only 8 seem to be used in the current implementation, the design seems to leave open the potential for future devices to use the 8 pins on each side for different things, using dynamic recongfiguration to figure out the orientation and maintain reversibility.
#30 | Written by Rainer Brockerhoff on September 25, 2012.

@Alan, from the look of the contacts inside the device, 1A per pin might be reasonable, and power depends on the voltage too. With current technology, I see no real problems with switching the pins.
#31 | Written by RF9 on September 25, 2012.

Never mind. I re-read the article fully and it answers my question.
#32 | Written by RF9 on September 25, 2012.

Does the complexity of this cable make it nearly impossible for cheap 3rd party Chinese cables like we see for the 30-pin? I’m sure major companies like Belkin will legally license and sell cables for $30, but what are the chances we’ll see something under $10 on ebay, Amazon, etc. It sounds like these cables won’t be easy to build.

I bought a ton of spare 30-pins for traveling, work, bags, etc. for quite cheap. It looks like I’ll be paying $30 a pop for lightning cables.

Thanks.
#33 | Written by Gopiballava on September 25, 2012.

@abaraxis: You don’t really push power. If something can handle 5v, then the only difference between a high or low current supply is whether it allows you to draw power. Hooking up 5v power where you expect 5v signal is generally not bad. Hooking up power in reverse or 5v where you expect 3.3v is not good.
#34 | Written by Alan on September 25, 2012.

Rainer, any guess as to how much power the 8 pins together might be able to both push and pull? It seems to me there is a difficulty in having programmable I/Os that are used as current sources or sinks in that whatever switches them needs to handle DC as well as high frequency signalling. Seems like this could result in a power limit per pin.
#35 | Written by Rainer Brockerhoff on September 24, 2012.

Just wait until you can’t step out of the house unless you sign the updated use agreement proffered by your “intelligent” front door!
#36 | Written by James Smith on September 24, 2012.

Interesting article.

“Now excuse me, I have to go and spend the rest of the week updating the firmware in all my cables.” LOL.

(Not looking forward to this inevitable time sink.)
#37 | Written by Rainer Brockerhoff on September 24, 2012.

@Fabio: “I can’t recall any appliance that assumes which one is the hot and which one is the neutral.” Well, this really matters only if the ground pin is also connected. I recall several older appliances (80s and 90s) where ground and neutral were interconnected or wired such that something would burn out if hot and neutral were swapped. Modern power supplies don’t care unless you really buy the lowest quality.
I’ve been planning to blog about the “disastrous” part for over a year, but had little time for research. Maybe later.
#38 | Written by Fabio Mazarotto on September 24, 2012.

Ok! I couldn’t be more wrong! I’m sorry. Gonna get home and use my Test Tool! ^^
#39 | Written by Fabio Mazarotto on September 24, 2012.

“…neutral and hot pins will be reversed, which can be dangerous if you plug an older 3-pin appliance into such an adapter.” — I can’t understand why once there’s no standard way to wire the hot and neutral plug holes. I can’t recall any appliance that assumes which one is the hot and which one is the neutral.

Anyway, do you have any additional material about the ‘disastrous’ change of standard in Brazil?
#40 | Written by Rainer Brockerhoff on September 24, 2012.

I never approve anonymous comments, but here’s part of what one said:
“…with this, you would have to change the ‘smart’ cable standard everytime you need a special interface. or you will have encoder/decoder on each end… again! now you have the cost of encoding/decoding in the cable AND in the devices… effectively killing all your ‘cost saving’ shenanigans.”
No. When you need a new interface, nothing changes in the devices, since the encoder is adaptive; only software changes. The cable/adapter itself has to be built with a new decoder, of course.
#41 | Written by Rainer Brockerhoff on September 24, 2012.

@someone: “Are you trying to say that the Lightning will not be using differential signaling? Or that it isn’t really digital either?”. No, I’m saying the pins on the connector (when switched in as data) are really digital, and any differential signals will be generated (if at all necessary) by the chip in the plug.
We really need someone to pull out the signals and check them on an oscilloscope…
#42 | Written by someone on September 24, 2012.

“well, I was being a little strict here. When a hardware designer says “digital” it usually means a signal that can assume two states: on or off. The differential signals used on USB and nearly all modern interfaces are, strictly speaking, non-digital, since they can assume any state individually; it’s their difference that encodes a digital signal.”

Are you trying to say that the Lightning will not be using differential signaling? Or that it isn’t really digital either?
#43 | Written by Rainer Brockerhoff on September 24, 2012.

@someone: “…massive data processing without charging does not sound sensible. Thus I would expect a pin to be reserved for charging.”
You’re still thinking in terms of fixed pins. Suppose a Lightning-to-VGA adapter; there’s no charging, it just needs a little power for the chips in the adapter. Suppose a charger connected to the USB2 cable; there’s no data, in can switch all (or most) pins over to carrying charging current. Suppose some future higher-speed interface to some sort of self-powered equipment; there’s no power passing either way, so all pins can carry data, and the adapter chips can be powered from the other end. We’ll see when the specs come out.
“You noted that USB3 ‘can be called digital’. I’m pretty sure it actually IS digital… ^^” well, I was being a little strict here. When a hardware designer says “digital” it usually means a signal that can assume two states: on or off. The differential signals used on USB and nearly all modern interfaces are, strictly speaking, non-digital, since they can assume any state individually; it’s their difference that encodes a digital signal.
#44 | Written by someone on September 24, 2012.

“All 8 pins are used for signals, and all or most can be switched to be used for power.”

I doubt this one. Of course that would be technically possible, but massive data processing without charging does not sound sensible. Thus I would expect a pin to be reserved for charging. That would be more robust too.

A sidenote: You noted that USB3 ‘can be called digital’. I’m pretty sure it actually IS digital… ^^
#45 | Written by Rainer Brockerhoff on September 24, 2012.

🙂 of course that’s taken care of, or you’d be reading about such cases for a couple of decades already!
#46 | Written by Abaraxis on September 24, 2012.

Sweet, so you will be able to kill hardware from software by poshing power down a device’s data lines.

Solipsism Gradient

Boom: Pins

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