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29 October 2007 @ 12:47 pm
iTrip Laptop mod  
The idea is to embed the innards of a Griffin iTrip Dock (info here) into the innards of my laptop.

The iTrip is designed to only function when connected to an iPod. The iPod sens special codes to the iTrip via a serial interface to tell it there is music playing. The iPod connector must be removed, pins located and traced, and somehow my laptop has to provide power and the proper serial commands to operate the iTrip.

What I know
After many hours of eyeballing the iTrip's innards with a magnifying glass and cross referencing the pins with an iPod pinout, I have located and identified every pin the iTrip uses:

3-Audio Left
4-Audio Right
11-RS232 Ground
12-RS232 TX
13-RS232 RX
21-RS232 Enable
23-USB +5V
25-USB D-
27-USB D+

IT IS IMPORTANT to note that the pins are not arranged on the board of the iTrip exactly according to the iPod pinout! BE VERY CAREFUL!

RED = Pins used by the iTrip
GREEN = Pins not in use

Apparantly the iTrip operates completely over RS232, broadcasting whatever audio comes through pin 3 and 4, when the proper commands are received. I also found that the USB connection is a simple pass-through. This means the iTrip doesnt use the USB connection at all, nor does it draw power from USB. It may as well not be there, and it my case it will not be used at all.

The serial connection
After a quick google search I found that all commands use the Apple Accessory Protocol. As soon as I fingure out how the hell this works I will be able to power the device on. Until then I have a bit of soldering to do on some really tiny pads on the iTrip.

-A laptop's LPT port delivers +3.3V across its data lines rather than the standard +5.0V. This will allow me to turn the iTrip on and off with commands sent to &h378 (basically, 0x00 for off and 0xFF for on)
-The iTrip's LCD has few enough pins (~20) to be attachable to a thin cable set and mounted in the laptops LCD panel. Likewise the selector switch can also be relocated.

(Anonymous) on January 27th, 2009 06:23 am (UTC)
did you manage to crack it?
hi steve, just wanted to know if you managed to crack this one and transmit music from your laptop using the i-trip?
Tobias AndersenTobias Andersen on May 14th, 2012 05:07 pm (UTC)
Did you manage to connect it to your laptop?
I have an old iTrip gathering dust that i want to rip open and connect to my macbook.

If you know what pins i need to solder to an usb + jack, i will be forever grateful. =)

Thanks in advance.