A DIY Digital Output Dock for the iPod/iPhone or iPod as a Media Server

[-=Germania=-]

Hey guys,


I have been doing some serious thinking in building a Dock for the iPod Touch/iPhone.


Primarily concerned with digital audio:

The base of it would involve using the readily available RD Dock PCB from Ridax seen here: iPod/iPhone Dock Connector ordering

The Microchip PIC 16F688 hooked up to an Apple Authentication Chip (likely pulled from a cheap AV cable from china) to enable output the raw audio/video data to the PIC (192k baud rate).

Using SPI Master Output to a ltera® MAX® II
CPLD (converts to I2s) which could go directly to a spdif converter, high grade DAC like the Opus/Buffalo (balanced madness!), etc.

Internal Data all done using the RS-232 protocol to negate any clocking problems.

The only thing that concerns me is that the 16F688 does not have very much memory (4kx14) and I am unsure of the size of the program for the conversion. The PIC should be pretty easy to program and the software could be done by multiple people. If you know C++ and/or worked with MPLAB and/or programed a simple proc like an 8951/2, ou help would be appreciated. I am not a good C++ programmer admittedly, but better with proc level commands and assembly (just like hardware better).


For use with an LCD display and Remote:

Switch the 16F688 with a much more capable PIC chip.

-256k of program memory or more
-24 or more I/O Pins
-RS-232 protocol
-SPI Interface

For the LCD Display, I would go with an LCD from Matrix Orbital because they also have Keyboard interface controllers, and built in RS232 along with drivers, etc. to make Dev time MUCH less. That LCD Display could actually be part of an external remote controller using RF much like a media server setup that would require a very small RF Chip for data transmission.

There might also be some abilities to get high quality video from the serial ports of the iPod and output to a better format like HDMI (doing Audio and Video) or just a standard DVI/VGA video only connection. I haven't done any research on this part though.



Both Configurations will have these abilities in addition to those listed:

- Analog Output
- Analog Line-in
- USB Data
- 12V Charging
- S-Video Output

The end result would be one "Hellofa" sweet transport and clearly the most awesome/capable iPod Dock anywhere.

I am throwing this out to the DIY community and am getting feedback from some professors on specifics. However, I am a full time student with many projects that I gave my word to finish as soon as possible. Ethically, it would have to wait another month or two to get started. Plus, I have a much more rigorous class schedule next term. However, I would be happy to help out as much as I can and we might see some first time posters who are other students at the university.


[size=small]Whats the feedback? Anyone Interested in starting this up?[/size]

 

[Mellow Mushroom]

The software would be pretty complex, but much of the code can be ripped. Better would be to directly tap the I2S output from the DAC chip of the iPod, wouldn't it?

 

[-=Germania=-]

This is a direct communication line with the main processor and the only way to get true digital out from the iPod that I can find from the internet.

I don't know what the internal processor hookups are and it would require additional feedback programming if it is even possible using the processor pretty much like a feed-through. It would be amazing if it was though!

I think that one way you could get digital output from the DAC chip would be to open up the iPod and split off some of the doublly used pins for those needed and just use a simple cable solution. I just don't feel a real want or need to take an iPod apart for that feature, especially since I won't still have it 5 years from now.

However, there is a proprietary protocal that apple uses:
AdrianGame : iPod Accessory Serial Protocol
Apple Accessory Protocol - nuxx.net
for the serial port and I just don't think that we can get a separate protocol on the return line without some really super engineering. We do have many smart people here with some serious skills who could be real contributors on that end.

I am actually more worried about memory than anything else for the program. The way it is set up from a hardware standpoint is for ease in making since this is not a commercial product and it would be nice to keep parts to a minimal. I2S would be pretty sweet...

 

[Mellow Mushroom]

A CPU or some kind of programmable chip would be required, so it seems like only hardcore DIY people would be able to implement it, unless someone like amb labs decides to offer a kit. Why not just smash the iPod on YouTube to protest Apple's decision not to add a digital out? Then we can have what we want next year, when the next model is introduced.

 

[Ron.id]

Maybe this thread tried the same thing?

 

[error401]

I think AVRs are easier to work with; the C development tools are free and open source, the architecture actually makes sense, and every device functionally operates identically. I found PIC really a pain when I first started working with micros, and now use AVR pretty much exclusively. I think ATtiny84 would be sufficient for this project (lacks a UART though which might be a pain), but using a mega (like ATmega168P) would be easier and safer (and you can leverage Arduino code), but the package is larger. If you're already set up for PIC development, nevermind

.

I don't know anything about the Apple chip, if you have details I'd be interested in seeing how Apple has this set up - or were you just planning on sniffing communications and emulating an existing interaction with it?

If I understand correctly, you want to use the Apple chip to pull data into your device via the UART? At 192kbps? That's too slow...what am I missing? Along the same lines, how are you planning to get the clock out of the iPod, and how do you plan to synchronize that clock with the SPI/microcontroller clock? Not sure how your serial data scheme is going to work in real life, but maybe I'm missing how Apple has set up this interface. When I saw those S/PDIF output devices available on the market I was assuming there were pins on the iPod that could be configured somehow to output S/PDIF or I2S directly. Wouldn't it be advantageous to just figure out how to enable that and forget about clocking the data through the micro and into a CPLD?

Sorry for the rambling late night reply. Interesting idea, but I see some hurdles to overcome.

 

[-=Germania=-]

The original speed rate is 19200 baud - higher rates (up to 57600 baud) work properly (tested the 5G) but make trouble sending large amounts of data (picture blocks) faster than 38400 baud. The Honda Music Link communicates at 9600 baud.

 

[error401]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif The original speed rate is 19200 baud - higher rates (up to 57600 baud) work properly (tested the 5G) but make trouble sending large amounts of data (picture blocks) faster than 38400 baud. The Honda Music Link communicates at 9600 baud.

So obviously the audio stream doesn't go over the async serial link, where does it come from?

 

[manaox2]

I'm really not saying that I wouldn't like making a dock for myself to get the digital out myself by reverse engineering something like the wadia itransport, but I would hate to get caught, especially if I was the one leaking how I did it. Apple would put me in a cider press.

 

[error401]

Quote:

Originally Posted by manaox2 /img/forum/go_quote.gif I'm really not saying that I wouldn't like making a dock for myself to get the digital out myself by reverse engineering something like the wadia itransport, but I would hate to get caught, especially if I was the one leaking how I did it. Apple would put me in a cider press.

Yea, the DMCA really is too bad.

 

[-=Germania=-]

I am not trying to reverse engineer the Wadia. Trust me when I say that I am not planning on buying one any time soon if ever. Just thought it would make a fun project. A simple solution would be an A/D converter - but that isn't pure digital is it?

However, that would likely give a good result if using it in your home theater system where it can be better translated to prologic.

If there is no interest, then there is no interest. Apple has no lawsuit against me since I used legal means to find out information and I am not copying anything here.

At any rate, I came up with a design that is in dire need of my money and attention for the future....$600 of parts.... If it turns out well, I will definitely post it up along with the finished product. The iPod dock is a lot of work and will definitely still be worked on, but now not as my main side project.

Meh.

 

[error401]

Quote:

Originally Posted by -=Germania=- /img/forum/go_quote.gif If there is no interest, then there is no interest. Apple has no lawsuit against me since I used legal means to find out information and I am not copying anything here.

They can claim that any protection of the digital data is for copyright protection purposes and charge you under the DMCA. Apple is known to be very hostile to reverse engineering.

You could use an A/D, but really it's just an extra analog->digital step. Many receivers digitize all their inputs now so they can put them through DSP, so you may as well use the A/D converter there instead of sticking it in a separate box. You could also modify the iPod to bring the I2S digital lines to the dock connector.

 

[-=Germania=-]

Apple has some real issue with innovation if it destroys it at this turn where it is something not meant to cause harm to anyone. It is meant as a new product different from anything out there.

I just want to build and learn, coming up with something useful to me in the long run. Tip-toeing even when you got the information legally and are not copying design...it is just sad.