Engineering

Introduction

This page gives an idea about the internals of the iPod 3G 30GB. It consists of collected information that can be found on the web. I've included some pictures from other sources. I've refered to those sources explicitly.

Development

Electronics Design shows a nice article about the development of the iPod.

Internals

Both Anandtech and Portelligent (via EEtimes) offer information about the iPod. The information on Portelligent is only commercialy available. Anandtech shows the iPod opened (iPodBattery shows how to open an iPod yourself - not advices by me).

Topside:

Topside after removal of the hard drive:

IC side:

The central chip in the iPod is the Portalplayer PP5002. It is the chip that controls the iPod (user interface, peripherals, and performs the audio decoding.

The chips is called an SoC (System on Chip), because it integrates many components performing different fucntionality. A block diagram of available functions is shown below:

As can be seen, it contains two ARM7 processors, and a lot of support for peripherals and control.

Wolfson Microelectronics provides the WM8731, the codec with integrated headphone driver. It is chosen because it connects to the PP5002 so well.

Some other chips of interest are:

• Texas Instruments Firewire Driver.
• Samsung 32MB BGA SDRAM chip, which serves as a buffer for songs, not having to acces the HD constantly.
• Philips Semiconductors Power Management and DC-to-DC convertor ICs.
• Cypress Semi USB controller.
• Sharp provides a1MB Flash for firmware.
• TI bridge interface to control the HD.

Other major components:

• Toshiba provides the 1.8" hard disk (for the iPod mini, this is Hitachi).
• The touchpad wheel and controller is made by Synaptics. More information can be found at mp3.com.
• The brand of the battery is unknow. Suspicions are Sony, or a Danish company called Danionics. There has been a lot of fuzz about replacement of the battery. For info about how to get most out of your batteries, see the BatteryUniversity. and the iPod Battery FAQ.
• The brand of the LCD display is unknown.
• A disassembly of the dock.

Software

• PortalPlayer offers a development kit, as shown by their firmware documentation.
• Quadros Systems provides the iPod OS.
• Somebody managed to get Linux running on an iPod. Funny exercise, providing some background information on the device.
• Daniel shows how to copy partitions of the iPod to disk images.
• iPod iTunes database format.
• The iPod diagnostics mode.
• iPod workaround.

European Volume Limitation

Due to European regulations, Apple decided to limit the volume on the iPod. Apple's product information on the web and the iPod FAQ contain no reference regarding this limitation. The FAQ even states in general:

• Question 13: Will music sound as good on my iPod as on my CD player?
  Answer: iPod is designed to provide the best-quality sound. iPod has a powerful 60 mW amplifier so it can deliver audio as loud as you want...

Apple's European sites contain no reference to the limitation whatsoever, e.g. the Dutch website reports exactly the same power figures (the word "max" is of no use here, you could also report 50kW). The only hint can be found in the iPod 1.2.2 updater (for Europe only) notes, where Apple refers to EN 50332-1 compliancy. Some people claim it affects the sound quality.

A German site refers to the specification of this EN 50332-1 standard. Basically it consists of two parts. The first part demands that mobile equipment should be limited to 100dB(A) sound pressure using the accompanying headphones sold. The second part constraints the output power of the device, hence covering any combination of equipment and headphones.

Several sources on the web claim the French government is the actuator of this law, because they want to protect children from damaging their ears caused by loud sound sources. I'm quite fed up with a government (which I can't choose), which in a European context chooses for a standard that assumes worst case scenarios. A lot of music is not recorded at maximum level, and a lot of good quality headphones are low efficiency. Thanks to the French government that these headphones are excluded from my life.

Currently, there are patches available to eliminate the volume restricion. For OS-X the best I know of is goPod, which just eliminates the restriction. Another one, called iPodVolumeBooster, is changing the volume of the iPod. I've compared my 3G iPod with an US 4G iPod, and after the modification these are both as loud. PC users can use euPod, which boosts volume as well.

Though safe, if you don't want to patch the firmware of you iPod, you can change the volume of your songs. Changing the volume of an MP3 file by changing only a tag can be accomplished on a Mac by using iTunes (select one or more song, Get Info, Options Tab, and use the slider to attenuate or amplify). Volumeboost. The effect of attenuation and amplification is very obvious, although you'll have to apply it each time you add new tracks to your database, which is easy to forget.

Using the sound check option might also help boost the volume of some tracks. There is a bug in the way Apple applies the sound check option to songs in iTunes vs. the iPod. A fix consists of using Dave's script (compensating for the bug on the iPod), in combination with MP3-Rage to adjust the volumes of your tracks to the same level (and turn of the sound-check option). The only drawback is that you have to disable fully automatic synchronisation between the iPod and iTunes.

Links

Also see Tushar Jain's pages for alternative information about the iPod internals. He's wrong about the brand of power management chips though (this is Philips Semiconductors, not Linear Technology).