STMP 3550

The SigmaTel D-Major STMP 3550 is a digital signal processor system-on-a-chip used in the first iPod shuffle. It features a 32-bit ARMv6 processor core clocked at 75 MHz, along with several integrated controllers. It is unique in being the only non-PortalPlayer or Samsung SoC used in the iPod product line. It was also used by competitors such as MSI, Creative, Samsung, and SanDisk.

It has the following features, not all of which were used by the iPod shuffle:


 * Digital signal processor
 * DAC, ADC, and amplifier
 * Headphone output
 * Microphone input
 * Line input (e.g. for FM radio tuner)
 * 5-band equaliser
 * USB 2.0 mass storage controller
 * Battery charging and temperature monitoring controller
 * LED and LCD controller
 * Flash memory and ATA hard drive support
 * CompactFlash, SD/MMC, and SmartMedia card support
 * MP3 and WMA decoder
 * Support for Janus WMA DRM (disabled on iPod shuffle)
 * MP3 encoder available on STMP 3560 model