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The fun way of doing this is to open up whichever iPod you have, identify the Wolfson DAC you have, steal the I2S signal from those pins and send them to unused pins on the dock, make a dock connector to steal those signals, open up your Pico and solder to the I2S input of the Wolfson WM8740. That's a pretty tall order cause you could destroy both your iPod and Pico in one afternoon. Either that or you could pay MSB for their iPod transport. Non-video iPods have more unused pins than video-enabled iPods, but I think you could still work something out with the existing pins. Check out Apple iPod dock interface pinout and signals @ pinouts.ru.
While difficult, it sounds like we're approaching the realms of possibility. Would this modification require the cable to be permanently affixed to the Pico? Would it disable the USB input? I plan on using mine both for portable and work (off of a laptop and would therefore still need the USB input to function) applications.
Is there anyway to get a similar mod to work without modding the Pico?
While difficult, it sounds like we're approaching the realms of possibility.
Everything is possible, it's a matter of risk vs outcome.
Originally Posted by rippingdragon
Would this modification require the cable to be permanently affixed to the Pico?
I would assume that you could make a jack on the Pico (if you find any room in there to use this), you generally need 4 wires for I2S, so you'll seriously need to consider your options. Perhaps having a small female connector beside the Pico with wires going in it will be most practical as I doubt you can find a 4-contact jack small enough to fit inside the Pico.
Then it will only be a matter of building an iPod connector with a matching plug.
Originally Posted by rippingdragon
Would it disable the USB input? I plan on using mine both for portable and work (off of a laptop and would therefore still need the USB input to function) applications.
Of course not, USB does not come into the picture at all, you just won't be able to use it at the same time.
Originally Posted by rippingdragon
Is there anyway to get a similar mod to work without modding the Pico?
I would probably just hardwire the iPod connector into the Pico to save on the connector. It seems crazy to think about soldering straight to the pins of the dock, but I did it for another diyMod just the other day and it wasn't so bad with just two strands of SPC. Practice makes perfect. Anyway, you could probably remove the input connector for the Pico's amp portion and rewire things as needed. Throw the dock connector wire through there, send the signal to the DAC, let the amp do the rest.
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If you wanted to use a connector, there are lots of pretty tiny connectors. You could start with mini USB type B, they're pretty tiny. You'll need 4 conductors plus ground, which should be fine on the shield.
I would probably just hardwire the iPod connector into the Pico to save on the connector. It seems crazy to think about soldering straight to the pins of the dock, but I did it for another diyMod just the other day and it wasn't so bad with just two strands of SPC. Practice makes perfect. Anyway, you could probably remove the input connector for the Pico's amp portion and rewire things as needed. Throw the dock connector wire through there, send the signal to the DAC, let the amp do the rest.
If anyone gives this a go (either hardwired or with a new connector), could they please post a guide with pictures. It would be most helpful to the less competent (i.e. myself)
If anyone gives this a go (either hardwired or with a new connector), could they please post a guide with pictures. It would be most helpful to the less competent (i.e. myself)
Cheers!
Considering this involves soldering 4 wires to a the pins of a SSOP 28 chip (it's less than 1cm square), it's generally not recommended for beginners.
To clarify one of my previous questions:
Why isn't it possible to use the USB port as the connection if you perform the appropriate mod to the iPod? Is this port looking for a different signal form/format?
To clarify one of my previous questions:
Why isn't it possible to use the USB port as the connection if you perform the appropriate mod to the iPod? Is this port looking for a different signal form/format?
Yes. First of all, USB has 'host' and 'peripheral' devices. The host is responsible for mediating the bus and there must be exactly one on each bus (it's also responsible for providing power). Peripherals are attached to the host, and provide services to it. Peripherals can't communicate with each other, only host<->peripheral communication is allowed. Both the iPod and a USB sound device are USB peripherals. Connecting them to each other will do nothing since there isn't a host on the bus, and no way for them to communicate with each other.
USB On The Go (OTG) changes this a bit so that it's possible for peripherals to sort of 'be both' and talk to each other directly. Unfortunately the iPod doesn't support USB OTG, and there's not really any reason for Apple to provide support, so that's a no-go too.
Furthermore, the iPod presents itself on USB as a Storage Class device, which is simple block-based storage like a hard drive. There isn't any way to get or send the iPod real-time audio data over USB.
It's probably possible for a USB host stack to be written for RockBox or iPod Linux (the PortalPlayer CPU in the iPod has a USB port that can be either a host or device) that could potentially allow connection of a USB audio class device for audio playback. You're welcome to try - but tapping the I2S lines is sure to be much simpler. This would be pretty cool though.
To clarify one of my previous questions:
Why isn't it possible to use the USB port as the connection if you perform the appropriate mod to the iPod? Is this port looking for a different signal form/format?
USB is USB (Master - Slave communication controlled by Master, which the iPod is not), I2S is I2S (simple audio digital transfer protocol, controlled by lots of chips - USB receivers, SPDIF receivers and of course DACs), no relation between the two.
Rants: - there - in or at that place; to or into that place; at that point or stage; in that matter, respect, or relation; used interjectionally to express satisfaction, approval, encouragement or sympathy, or defiance
- their - of or relating to them or themselves especially as possessors, agents, or objects of an action; his or her
- they're - they are
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