Follow Slashdot stories on Twitter

 


Forgot your password?
Close
typodupeerror
×
Hardware Hacking Power Apple Build Hardware

Hardware Hackers Reveal Apple's Charger Secrets 371

Posted by kdawson from the hard-charging dept.
ptorrone writes "In this 7-minute video we explore the mysteries of Apple device charging. Usually, device makers need to sign a confidentially agreement with Apple if they want to say their charger 'works with iPhone / iPod,' and they're not allowed to talk about how the insides work. If you don't put these secret resistors on the data lines too, you get the dreaded Charging is not supported with this accessory. We demonstrate how anyone can make their own chargers that work with iPhone 4, 3Gs, etc."
This discussion has been archived. No new comments can be posted.

Hardware Hackers Reveal Apple's Charger Secrets More

Hardware Hackers Reveal Apple's Charger Secrets

Comments Filter:

  • Resistance is Futile (Score:5, Funny)

    by Maarx ( 1794262 ) on Tuesday August 03, 2010 @01:54PM (#33126874)
    Resistance is Futile

  • Good Lord! (Score:2, Funny)

    by RenHoek ( 101570 )

    Is it wrong for me to get a bit hot under the collar, seeing a geek girl with such an impressive electronics workdesk?

    • Re: (Score:2)

      by Aladrin ( 926209 )

      No, I always feel particularly attracted to girls that have tech skills, too.

      • Maybe it was the way she moved her hands up and down the soldering iron and then flicked the tip. Just hope she does not go all Lorena Bobbitt with that thing.

    • I could think of much worse things to get aroused by. Especially with electronics.

    • Re: (Score:3, Informative)

      by Bearhouse ( 1034238 )

      Whatever turns you on, dude. She's certainly well-geeky, but 'hot' she's not ;-)

    • Re:Good Lord! (Score:4, Funny)

      by Spazntwich ( 208070 ) on Tuesday August 03, 2010 @02:11PM (#33127228)

      Want to cry into your underwear with nerdlust?

      Read an article from http://badphysics.wordpress.com/ [wordpress.com], spend a few futile minutes googling for more pictures and trying to internally reconcile her ravishing looks with such effortless eloquence and boundless intelligence, and then fall even deeper into self-loathing despair with the realization that even your hypothetical best version of yourself wouldn't be good enough for her.

      Or, you know, don't. But you get my point. Hopefully, because I don't.

      • Damn, I want her. Too bad she probably doesn't want me :(

      • Re: (Score:2, Insightful)

        by Orestesx ( 629343 )
        Dude, that is busted. Do not want.

      • Re: (Score:3, Funny)

        by elrous0 ( 869638 ) *
        There is something off about that girl. I can't quite put my finger on it, but I think she may be a mandroid.

      • and then fall even deeper into self-loathing despair with the realization that even your hypothetical best version of yourself wouldn't be good enough for her.

        Why? Does she prefer girls?

      • Re: (Score:2, Insightful)

        by cgranade ( 702534 )
        Grow up. The author of that blog is a real, honest person. I don't think she likely appreciates that kind of treatment. Has it ever occurred to you that Sarah may actually find your comment? That there is a person behind that picture? That Sarah may not, in fact, be writing to entertain your "nerdlust," but because she has an interest in, say, science?

        • Re:Good Lord! (Score:4, Insightful)

          by DrgnDancer ( 137700 ) on Tuesday August 03, 2010 @03:46PM (#33128984) Homepage

          Dude, has it occurred to you that given she has a science blog with a very nice picture of herself setup obviously next to it kinda saying "Look at me, I'm a pretty little geek girl", she probably likes the attention? I'm not trying to knock her or anything, it's a perfectly normal and reasonable thing to like attention. I also greatly doubt that she wants to have wild monkey-sex with any great percentage of her readers, I'm not saying that either. She clearly likes to be paid attention to: both for her obvious intelligence and for her equally obvious good looks. Her website gives her to opportunity for both in a very safe and impersonal way, good on her. Don't expect people to ignore that she's pretty though.

          Personally I kinda liked Ada better. I'm more of a technologist than a scientist, and I like the alt-girl look. To each their own though.

        • Re:Good Lord! (Score:4, Interesting)

          by shiftless ( 410350 ) on Tuesday August 03, 2010 @08:26PM (#33132612)

          I guarantee Sarah is perfectly content enough and at ease with sexuality, being a grown woman of good looks and high intelligence, that comments by random nerds on a geek site don't at all even register on her radar as a source of concern. You don't need to "protect" her from the evil lusty nerds, he-man, she's gonna be OK.

      • Re: (Score:3, Interesting)

        by shiftless ( 410350 )

        Read an article from http://badphysics.wordpress.com/ [wordpress.com] [wordpress.com], spend a few futile minutes googling for more pictures and trying to internally reconcile her ravishing looks with such effortless eloquence and boundless intelligence, and then fall even deeper into self-loathing despair with the realization that even your hypothetical best version of yourself wouldn't be good enough for her.

        Except I know I actually *could* bang her. And I'll go ahead and tell you, just because she's good looking and sm

    • Re:Good Lord! (Score:5, Informative)

      by nb caffeine ( 448698 ) <nbcaffeine@gmail. c o m> on Tuesday August 03, 2010 @02:17PM (#33127346) Homepage Journal
      Not only does she have a well stocked desk, she has her own company and sells some geeky stuff to us tinkerers: http://adafruit.com/ [adafruit.com] Her monochron pong playing clock was featured on /. a while back.

    • Re: (Score:2)

      by JavaBear ( 9872 ) *

      Nope. I got hot under the collar seeing that desk too.

    • Its not "wrong" as in somehow morally objectionable.

      However, feeling the need to discuss it on Slashdot, making comments that amount to "OMG, its a GIRL!", while still not immoral, are pathetic.

      You must live in either a basement, or Saudi Arabia, and never see any real girls. Whichever it is, just get out more.

    • Re: (Score:2)

      by mcgrew ( 92797 ) *

      Damn, now I have to RTFA!

  • Better keep looking.

  • Right to repair [wikipedia.org] our own electronics though? (Or build interface devices)?

    • Re:Should we have a... (Score:5, Insightful)

      by betterunixthanunix ( 980855 ) on Tuesday August 03, 2010 @02:28PM (#33127580)
      Do you even have to ask? Yes, we should have a right to repair, and a right to build interface devices.

      People often talk about how wasteful Americans are and the problems of a throw-away society. If people were more willing to repair their devices, especially complex electronic devices (most of which fail because of simple and repairable problems, like a broken lead), we would be better off. Aside from less electronics in landfills (let's face it, few people actually dispose of electronics properly), people would not be spending their money so quickly, and presumable that would mean fewer debt problems (or they might just spend it elsewhere).

      Of course, we will never see anyone other than a few activists pushing this sort of mentality -- corporations have enjoyed ever larger profits because people are unwilling and unable to repair their own equipment (or to find a local repairman to do it for them).

      • Re:Should we have a... (Score:5, Insightful)

        by DNS-and-BIND ( 461968 ) on Tuesday August 03, 2010 @02:52PM (#33127982) Homepage
        Sorry to distract you from the "profit is evil" theme, but the reason consumer electronics can't be repaired in America is due to the fantastically high cost of labor there. But don't listen to me, read here [albanyvideoservice.com]:

        Do we repair DVD players?
        Yes and no. We recognize the fact that DVD players, like most electronics, were expensive when new. Now that the format has been on the market for over a decade, the cost of players has dropped radically. Most models are less than fifty dollars with all of the features one would dream of in a player. Repairs on DVD players are only economical a small fraction of the time. We recommend Albany merchants such as Target and Radio Shack as being good places to consider the purchase of a new DVD player.

        The source is a video repair shop in flyover territory which charges $60/hour for labor. Here in China, I can get my DVD player repaired for $3-10 because the cost of labor is so low. Indeed, one of the delights of living here is you can actually get things repaired. I'm just so used to automatically buying a new electric razor, rice cooker, electric lamp, (etc) when mine breaks. Here, I can actually get it fixed! In America, don't even bother phoning the repair shop as they'll just tell you that the cost of a new unit is less than the cost of their labor.

        Don't let that put you off of blaming stupid Americans who are unwilling and unable to repair their own equipment and of course blaming those eeeeevil profit-makers. The only people who see the world the right way are a small group of activists, for example yourself!

        • Re: (Score:3, Insightful)

          by DrgnDancer ( 137700 )

          But you yourself admit to being unable or unwilling to repair your stuff, you just have access to cheap labor to do it for you. I mean sure, the American shop could work for $3-10... They wouldn't be able to pay for electricity to tell if the repairs were successful or not and they'd have to work out of a tent, but they could. The simple fact of the matter is that between the extremely small cost of electronics, and the generally quite reasonable desires of electronics repair people to be able to eat and p

      • People often talk about how wasteful Americans are and the problems of a throw-away society. If people were more willing to repair their devices, especially complex electronic devices (most of which fail because of simple and repairable problems, like a broken lead), we would be better off

        Hmmm... I have a car charger that has a broken lead. I accidentally snapped it while dissasembling to figure out why it was giving me problems charging. Now, it could be that lead, or one of the other minor parts. My optio

  • Not surprising (Score:5, Informative)

    by Glendale2x ( 210533 ) <slashdot@ninjam o n k ey.us> on Tuesday August 03, 2010 @02:06PM (#33127134) Homepage

    Lots of companies do this. APC puts a RS-232 serial port on a UPS but wait! They move the pins around so you need a special cable. Cisco used to have a product called the Gigastack that used a standard 6-pin Firewire cable, but no! Pins 1&2 were shorted in the "special" cables Cisco provided.

    • We all love to call out Apple when they design deliberate incompatibility into their devices, but there is a perfectly valid technical reason for what Apple is doing here, and, in fact, they are following a USB specification (which LadyAda unfortunaterly didn't even test).

      Without data communications or when suspended, devices may legally draw no more than 2.5mA from a host, which is useless for charging. In fact, even if you're generous and pretend they're connected, devices are not allowed to draw more than 100mA without negotiating for a higher current, which requires actually talking to the host, and 100mA is still too little to charge properly. 500mA is the maximum allowed by the USB spec, but devices must negotiate it (there may be too many devices on the bus for negotiation to succeed).

      Before there was a spec for "dumb" USB chargers, Apple used the resistors as a sentinel to avoid drawing too much current from undersized chargers in order to avoid damaging the host. This is a hack, but it works, and honestly, we're smart enough to figure out a couple resistors on the data lines. It's not like they're using crypto auth on the charger. They have a perfectly valid reason to do this. Devices which charge from "dumb" chargers aren't following the spec, though this is a common industry practice.

      As it turns out, the USB-IF came up with a USB Battery Charging spec [usb.org]. The spec is long and boring, but it boils down to: short together the data lines (no resistors required) and you indicate that you're a dumb charger that can supply anywhere from 0.5A to 1.5A.

      Guess what happens when you short the data lines of an iPhone 3G and supply 5V [marcansoft.com]. Did Apple just follow a standard? Incredible!

      (Yes, I'm not following the USB spec there by in turn using a USB cable to supply the 5V and not negotiating over its data lines. I didn't feel like grabbing a dedicated 5V PSU for the shot, so sue me.)

      • Re: (Score:3, Insightful)

        by IICV ( 652597 )

        Actually, I just wanted to point out that if you RTFA (instead of just WTFV), you'll see that Lady Ada does in fact acknowledge that the USB spec says some things. Here, I'll quote it for you:

        We thought "is there a enumeration chip inside every charger?" but since thats expensive and kind of overkilly we decided instead to read up on the USB protocol (go Jan!) In particular, in her fantastic book there's a part about the low level signaling states. Since you want to get the iPod charging, but NOT make it tr

  • i've bought iphone charging cables on ebay for $2 each including shipping and they all seem to work. via the USB and in my car. sometimes i've pulled it out a bit by accident and i get the error. put the cable all the way back in and it works.

    • Yeah. They work fine for a while. Part of what you're paying for is engineering. It's easy to provide something that looks like 5 volts to a simple multimeter.

      But you plug a cheap cigarette lighter USB charger in, and put a scope on it. Then do things like crank the engine, turn your AC blower on/off, etc, and see what happens.

      Good quality chargers typically have extra components to filter out the sort of nasty, very fast spikes (often 30 v or more) that come over a car's 12v (13 to 14 really) lin

      • Re: (Score:2)

        by Lumpy ( 12016 )

        Yup things like capacitors diodes and voltage regulators.

        Even the $4.99 cheapies I found online filter all that out. A DMM is junk for checking that use a digital storage scope.... less than .1v ripple from the cheapie I got online.

        Now the caps will blow up in 16 months... but that's a different issue.

  • How long will it be before the take down notice arrives?
    Someone download the plans, and put them up on a torrent site quick.

    • Re:Place your bets (Score:5, Informative)

      by v1 ( 525388 ) on Tuesday August 03, 2010 @02:53PM (#33128006) Homepage Journal

      Reading the article, it appears that the purpose of the resistors is NOT to lock out manufacturers, but to inform the ipod of the amount of current to draw from the charger. They found different manufacturers using different values of resistors. From the looks of it, one resistor sets the amount, and the other resister serves as a "checksum of sorts, complementing the other resistor correctly to verify the value. Getting the value wrong could very easily cause a fire, so this is important to make sure you get it right.

      This is not surprising, as USB does not allow variable voltage, and current is supplied completely on demand with no regard to the provider. So you either have your device set to draw a fixed amount of power (current) and limit your options to *1*, or you develop some simpler way to tell the device how much power (current) a device can demand from any given charger.

      The only other option would be to use the data pins and actually communicate over the usb spec normally and outright tell the device how much power to draw. (which is actually already in the USB specs) Apple would have probably preferred to go this route, but that would significantly increase the complexity of the power adapters. All the people that are whining about Apple being nasty about this need to get some education. Apple's other two options were to make chargers cost more, or to not be able to offer both fast (wall power) and slow (AA batts) chargers.

      The only group that's more thick-headed than the Apple zealots, are the anti-Apple zealots.

      • So you either have your device set to draw a fixed amount of power (current) and limit your options to *1*, or you develop some simpler way to tell the device how much power (current) a device can demand from any given charger.

        If current is within normal limits, supply +5V on the +5V line. If current exceeds normal limits, supply 0 V for a split second. The device ramps up the current it can draw until the charger starts cutting out and then steps down the current.

      • The only group that's more thick-headed than the Apple zealots, are the anti-Apple zealots.

        I am not a zealot of any sort, except anti MS. As it happens I own several Apple products and am planning to buy an iPhone 4 in a few months when they get its issues sorted out.
        That said: Apple tends to be pretty quick with the lawyers and take down notices.

  • secret resistors abound (Score:3, Interesting)

    by SpinningCone ( 1278698 ) on Tuesday August 03, 2010 @02:18PM (#33127358)

    i hate when manufacturers do crap like this to keep peripherals locked into a more profitable licensing agreement. Apples tendency toward total control is one of the things i don't like about them.

    tho other manufacturers are just as bad. i will never buy a Dell for my home for the same reasons. at work we had an Out of warranty gx 270 desktop. they were know for their bad capacitors in the power supply. so lo and behold the PS goes out. i have to spec a new one. at first i thought i would hop down to the local PC store and grabe a cheap PS for like $30 would work fine.

    found out that the motherboards on those dells had different pin layouts from regular boards. the connector was the same as your usual PS but the lines were scrambled. if you plugged in a PS from the PC store you would fry the mobo. thus i would have to get a new PS from the dell store at a cost of $115 ..

    we opted for a used PS from a 3rd party supplier for $30 instead.

    wish companies would back off and be more open. the way things seem to go we're heaed back to the old at&t days when it took a court action just to add a funnel to your telephone handset http://en.wikipedia.org/wiki/Hush-A-Phone/ [wikipedia.org]

    • Re:secret resistors abound (Score:4, Informative)

      by cynyr ( 703126 ) on Tuesday August 03, 2010 @03:41PM (#33128894)

      It looks more like a way to signal to the iPhone that it can go ahead and "fast charge" by pulling 1A, or "slow charge" by pulling 0.5A. They just didn't tell anyone about how to do it.

      As for your dell power supply, just get one of those "ATX power" extension things, cut in half, "scramble" the wires in the right way, get a working dell PSU, and then start selling it. see http://pinouts.ru/Power/dell_atxpower_pinout.shtml [pinouts.ru] for the pinouts.

  • usb standard chargers in china (and europe etc)? (Score:5, Insightful)

    by joostje ( 126457 ) on Tuesday August 03, 2010 @02:20PM (#33127386)
    According to wikipedia [wikipedia.org],

    China and other countries are making a national standard on mobile phone chargers using the USB standard.[13] Starting in 2010, Apple, Nokia, Motorola, Samsung and RIM will begin making handsets with a standard phone charger based on the micro-USB connector

    But the shown resistors don't look like the standard micro-USB connector. So is Apple breaking it's prommisses? Or am I missing something?

  • Confused (Score:4, Insightful)

    by Qwavel ( 733416 ) on Tuesday August 03, 2010 @02:21PM (#33127408)

    Doesn't it just use micro USB like all the other new phones?

    I thought that the EU had forced all of the cell phone makers to adopt micro USB for charging and that they had complied by adopting the standard everywhere (not just in the EU).

    I probably don't need to make this point here on /., but I think this is a great development. The convenience and cost saving to me as a consumer are substantial.

    Has Apple managed to avoid this?

    • Doesn't it just use micro USB like all the other new phones?

      I thought that the EU had forced all of the cell phone makers to adopt micro USB for charging and that they had complied by adopting the standard everywhere (not just in the EU).

      This is the EU that you are discussing. Rules don't come into force overnight. Also, it appears that the rules can be satisfied by selling an adapter. Apple sells such adapters.

  • than any company that makes products with custom dongles to interface/charge their batteries? All I see is that Apple found a way slightly more clever than just making a unique connector shape...

  • Chinese knock offs. (Score:3, Insightful)

    by Kenja ( 541830 ) on Tuesday August 03, 2010 @02:24PM (#33127466)
    Most third party chargers I see for Apple hardware are Chinese knock-offs purchased for under 20$ from eBay. I somehow doubt these manufacturers signed anything.

  • that they are not doing it the usb battery charging way:
    https://secure.wikimedia.org/wikipedia/en/wiki/Universal_Serial_Bus#Power [wikimedia.org]

  • How about some sort of web page with a description, instead of having to sit through a tedious video?

  • Could have done it without removing resistors. (Score:3, Insightful)

    by Ungrounded Lightning ( 62228 ) on Tuesday August 03, 2010 @08:59PM (#33132838) Journal

    There was a way to do this that didn't involve unsoldering and measuring the resistors.

    Tests with an ohmmeter and visual inspection had already shown that the charger tied each D line to an independent voltage divider across the supplied voltage. This produces the (Thevenin) equivalent of:
      - a voltage source at the same ratio to the supply voltage that the lower resistor's value has to the sum of the resistors' values,
      - in series with a(n equivalent series) resistance equal to that of the two resistors in parallel.

    Measuring the supply voltage and the unloaded voltage on a D line gives the resistor value ratio. You can measure the parallel equivalent resistance by either of two methods:
      - Shut down the supply, short + and -, and measure the resistance from the D line to the shorted supply.
      - Load the D line with a resistor to ground of known value that pulls the voltage down appreciably. (In the ballpark of cutting it in half is ideal.) Measure the amount it droops (and recheck the power supply voltage in case you pulled that down a bit, too.) This presumes the pullup resistor can handle 2x the normal current and 4x the normal power dissipation, for the duration of the test.

    With those two measurements you can calculate the resistor values. If they fall near standard values it provides a sanity check on your calculations and measurements. You only have to pull 'em off if there's an additional "black box" component hooked to the D lines that might foul up your measurements.

    (Of course if you already have the tools handy, pulling off and measuring the resistors may be easier. It also lets you check that there wasn't something else hidden in the circuit that you missed.)

Slashdot Top Deals

Our OS who art in CPU, UNIX be thy name. Thy programs run, thy syscalls done, In kernel as it is in user!

Close