iParty, a Novel Autonomous iPod Music Mixer

As of October 2007, the iPod had sold over 119 million units worldwide and as a result, has become the best-selling digital audio player series in history. With such a huge user base the iPod accessory market is even larger, as most iPod users own several iPod accessories. Within the iPod accessory market a void exists.

For iPod consumers there is a distinct hurdle to go from unplugging the headphones to plugging multiple iPods into a stereo system. For example, at college parties and gatherings the party goers are often forced to suffer through the sometimes poor musical taste of the party thrower. The iParty device allows several of the party goers to connect their personal iPods to the device and as a result, allow their personal musical taste to be heard.

An early sketch of the first iParty prototype is shown below.

Prototype

The iParty’s primary objective is to provide the consumer with the ability to mix multiple iPods into one standard stereo signal that can then be played on any sort of powered speakers or amplifier. The iParty’s secondary objective is to provide the best user experience possible without limiting or restricting the primary objective. The main features are:

• Automatic iPod detection
  • iPhone
  • iPod touch
  • iPod classic (starting with generation 3)
  • iPod nano (all generations)
  • iPod mini (all generations)
• Stereo audio mixing
  • Line level output
• Autonomous DJ mode
  • Random song playback
• iPod charging circuit
• One hand operation
  • Jog wheel with center select
• Graphical LCD
  • Used for displaying system information
  • Automatic backlight dimming
• Robust
• Low power
• Field upgradable
• Visually pleasing

System Level Design

To control the connected iPods the microcontroller sends specific commands via 19200 bits per second serial communication using standard 8N1 settings. The transmitted commands follow a strict ordered structure as shown below.

For example, to tell an iPod to play the currently selected song the following bytes should be serial transmitted:

0xFF 0×55 0×04 0×04 0×00 0×29 0×01 0xCE

The iParty enclosure, was first designed using the CAD software, SolidWorks. After a preliminary design was completed, a generic ABS plastic enclosure was modified to match the design.

Enclosure Design

Here are some pictures of the final project:

Printed Circuit Board Design

Inside View

Finished PCB

All 10MB of the final report can be downloaded here.