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Modding Different iPod Shuffle hack - a power supply + docking station

Discussion in 'Modding' started by Goldfish, 29 May 2005.

  1. Goldfish

    Goldfish New Member

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    I posted a couple of weeks ago about making a case for my iPod shuffle, which got some good responses. Thats an ongoing project which I might do over the holidays, perhaps even for my A-Level design project if I deem it to be a good enough idea.

    This idea is different. Naim made a bit of kit called the iSupply (a review of which is at MacUser). Step dad (owner of a 40GB 3G iPod) bought one and the difference IS noticable (much to my surprise). I know that the shuffle has much less sophisticated kit in it (appart from anything due to space restrictions), however I'm wondering whether I could make such a power supply for it. Even if its not going to affect sound quality, a dock style charger without the cost of an official "apple" unit would be great. Hell, while I'm at it I could even give it phono outs too, for my personal convinience!

    I reckon I could use some pretty generic parts of the base, a little project box from maplins would do, with one of those panel mounted female USB sockets you get on front of cases (had a pair of those hanging around for yonks now) might do the trick for the interface. The other advantage of these is the fact they have got the pins wired up AND labeled... an added plus which means I wouldn't have to mess with a USB cable to get the right pins.

    I there's also the possibiliy to have a USB out to connect to my PC, but I'm not sure whether that'd be worth it. I may as well take it out the docking station and go over to my PC, plug in and sync really, and simply have the docking station attached to my hifi.

    All I'm wondering is whether I'd be able to get an audio out from the male USB connector on the bottom, or whether I'd have to have a wire going to the headphone socket.

    I've done a little research and come up with some relevant articles:
    http://www.i-hacked.com/content/view/111/94/
    http://www.hackaday.com/entry/1234000700034044/
    http://www.ipoditude.com/archives/2005/02/hidden_features.php
    http://www.chipmunk.nl/ipod/ipodshuffle.html
    Any comments/ideas are welcome!
     
    Last edited: 1 Jun 2005
  2. Stickeh

    Stickeh Help me , Help you.

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    Good idea, i built a charger for my 3g 20gb ipod, easy enough, get an old socket, and a suitable battery pack solder up the right pins and your ready to go.
    Shove it in a box for it too look good :D

    My first one was simple and sat loose inside a card deck box, my new revised version uses 8 ( yes EIGHT) AA batteries to provide 12v to the ipod, this should give me more charge than the last one that used 2 AA and one 9v battery.
    The new one now sits in a maplin project box, and the plug will be held in with screws when i get round to it!

    Really helps, provides an extra 8-10 hours depending on battery types ( recharge-ables etc)

    As for your project the only thing i dont see happening is getting audio out from the USB port, UNLESS you can get it from say the apple docks. I know this is possible with an ipod and i plan to make this into good use with my next ipod project.
     
  3. Goldfish

    Goldfish New Member

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    I've been reading into the audio out thing. The FM transmitters can get audio out from the USB plug, but I can't really see how. There are extra pins on the connector, but it seems like they send a digital audio out... I'd need some sort of decoder to turn that into an analogue out (for say phonos).

    The only place I can think to get that at the moment is a FM transmitter (say the AirPlay), but I'd have to buy one to butcher it, setting me back about £30... which is more than an official docking station.

    What would be really great is if it uses a standard digital signal which I can decode using a suitable chip which I can wire up myself. But since I don't want to spend lots of money on the project (the inexpense being the entire point), I'd have to rely on other people doing research into it, or figure out a way to analyse the signal myself.

    The charger part looks to be pretty darn easy, for the dock just have a 5V supply input going to the appropriate USB pins, and I can hook pretty much any 5V supply up to that (could be a transformer, could be a battery pack). I wonder if a 300mA supply will give me any advantage over a normal 100mA supply, though. In theory, if I have my decoder chip there too, I can run that off the shuffle's power out (which must be there, or the FM transmitter wouldn't work... surely?), or simply have a 12V/15V in and split it up with a potential divider of some description and use the two new voltages accordingly.

    More research is required, methinks.
     
  4. Goldfish

    Goldfish New Member

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    Ok, I've decided to have a go myself. I've stripped down a microphone wire and tinned the ends, hoping to try and connect up to one of the "extra pins" on the shuffle and see if i can record an audio signal off it. So far, no luck unfortunatley. I've tried ground to each of the pins (including the standard data transfer pins...) and I've tried a few different combinations. It is of course possible I might need to short a couple of the pins for it to start sending.

    If anyone has an AirPlay, I would be indebted to you if you might possibly be able to take a photo of the inside of the connector :D
     
  5. Goldfish

    Goldfish New Member

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    After much pokinng and fiddling, I've come up with nothing conclusive.

    But I have found that shorting one or two of the pins causes the headphone socket to stop working.... HMMmmm.... However since my poking was with rather larger wire than I would have liked, I'm not sure exactly which pins. I could have been shorting the whole thing to ground, you never really know...

    I've not managed to find any sort of audio signal as of yet. There are some AC Voltages across a couple of the pins, but I can't isolate a specific signal from those. What I really need is a CRO and an amp and speaker to really analyse it. I'm going to have to make a small assembly which will let me connect up and monitor all 9 of the pins at once without having to stick bits of wire into the connector!
     
  6. star882

    star882 New Member

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    Could it be a S/PDIF output or even an AC'97 output?
     
  7. Goldfish

    Goldfish New Member

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    Certainly possible. Not totally sure how I'd tell if that was the case, though. I'll have to read up on that.

    Here are a couple of piccies of my current test rig. The shuffle is sitting in panel mount USB board, the sort you'd normally have stuck on the front of a case. This lets me test the normal 4 USB pins without having to stick any probes into the connector. However, at the moment I've got no access to the other 5 pins.
    [​IMG]

    Here is the rest of my test rig, including my beloved Fluke multimeter, and a pair of gnatty speakers which I found lying around. Works just fine for listening whether the headphone port is still doing its stuff.
    [​IMG]

    I did write down a table of voltages, which may or may not be relevant, we shall have to see. If they turn out to be relevant I'll definatly post them.

    If I manage to work out the mystery of the connector I might consider starting a project log thread while making the base!
    BTW: that is in fact a netgear router with green CAT5e cable lurking in the background.. I use it for doing line tests on ADSL lines :D

    My plan of action is as follows:
    • Persuade the physics department at school to let me use a CRO and some other bits and pieces for a lunchtime or two
    • Make a rig/assembly which will let me use all of the pins that are available on the shuffle's connector
    • Try all the combinations of shorting and combining the pins, and see if I can get any kind of coherant signal from any of the pins.
    • If I find an interesting signal, I'll need somthing to plug it into to try and decode it. For example if it is in fact SPDIF out, then I need to decode it into an analog out so I can listen to it.
    • Once I've found the signal, I need to be able to find a component small enough to fit into a base to turn it into a Line out, or alternativly take the signal out in its raw format and have another bit of kit to decode/amplify it, give it the right impedence so I can plug it into a line in socket on a pre amp.

    However the evidence so far is anything but encouraging. Some have reported a "noisy (analog) signal", which probably wouldn't be suitable for line out. Also, looking at the chip spec it has a headphone amp onboard, which my guess says goes straight to the headphone jack. No line out there. As far as I can see there is no line out from the chip itself, bu-ut there is the possibilty that there is a digital out somewhere that the spec doesn't talk about (probably because its not a main feature of the chip). I've not managed to get my hands on a detailed pinout from the chip either... which would certainly help a lot.

    An alternative that I can see would be to get the pinout for the chip, and manually dissassemble the shuffle (EAK!) and trace where each contact on the connector goes, and how its attached to the chip. From the spec, there seems to be pins used for LCD screens, Graphic EQ and other things like that... which might be where the extra contacts on the USB connector are going. Apparently all of the pins are used while the shuffle is in the factory (microscope pictures reveal marks on all of the contacts on purchase), likley for quality control purposes.

    However, I do NOT want to dissassemble my 1GB shuffle to do this. I might look into buying a broken one from somewhere in which I'd be able to do this tracing on. I'm sure the information I'd gather would be worth it for the greater good and all that ;)
     
    Last edited: 1 Jun 2005
  8. jmo

    jmo New Member

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    I’ve been trying to make an iPod Shuffle audio interface for a long while now, and I’m glad to see someone else is having a crack. I’ve also had no luck working with the digital outputs. I have, however, just discovered a device that converts the Shuffle’s USB to standard Apple Dock.

    It’s the Belkin USB to Dock Adapter for iPod shuffle. Yeah, great name, but its only A$30. Now, what’s the good of that? Well, the iPod Dock pin out is well document, particularly at here and here.

    More to the point, the Dock has dedicated left and right audio line out pins. Now I haven’t tried, so don’t hold me to it, but me thinks you could take one of these adapters and take the signal off those dedicated audio pins to drive an amp, and in turn, speaker.

    Anyway, enough from me. If I can’t get my hands on a scope and build some DAC circuitry that works, I may just use the Belkin.
     

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