SigmaTel STMP3xxx

Introduction

The SigmaTel STMP3xxx series is a somewhat popular System-on-a-Chip solution for portable audio players. They include CPU, on chip RAM and ROM, I/O to external storage devices, display, and buttons, USB interface, ADC and DAC, headphone amplifier, and a battery management interface.

The major SigmaTel STMP3xxx series can be devided into the STMP34xx, STMP35xx, and STMP36xx series. The STMP35xx series is backward pin and firmware compatible with STMP3410. The STMP36xx series is based on a different CPU.

SigmaTel STMP35xx Series

Overview

All STMP35xx chips in the series include a Motorola DSP56004-compatible 24-bit signal processor, 288KBytes of on-chip SRAM, and a high speed USB 2.0 interface. The chip also includes a mixer, DAC, ADC and provides interfaces to IDE Hard Drives, CD-DSPs, Flash memory, LCD/LEDs, button & switch inputs, headphone driver, FM tuner input & controls and a microphone.

Processing Unit

The processing unit consists out of a 24-bit DSP core modeled exactly after the Motorola DSP56004. It supports the identical instruction set, registers, addressing modes, as the DSP56k family of digital signal processors. The DSP is a Harvard architecture, simultaneously referencing an X data, a Y data, and a program element. The DSP can access a 16k x 24bits on-chip ROM and a 96k x 24bits on-chip RAM. A set of units provides interrupt control, timers, and a trace debug unit. The DSP comprises a set of three excution units as there are the separated digital filter, an ECC engine, and a bit manipulation unit.

Timing Unit

The STMP35xx includes a real time clock (RTC) with alarming functionality. A crystal oscillator drives a phase lock loop (PLL) providing required clock signals.

Analog Part

The DAC is a Sigma-Delta (ΣΔ) decoder which achieves a SNR more than 90 dB. The headphone driver accepts signals from microphone, analog audio in, FM radio, and DAC, and can directly drive low impedance headphones. The ADC includes inputs for microphone, analog audio in, FM radio, and a feedback channel from headphone amplifier input. The ADC supports MP3 encode features on some STMP35xx flavors.

Peripheral Interfaces

The digital interfaces will connect external digital devices like mass storage devices, I2C bus, displays, buttons, and switches. The connection the the chip core is provided by a memory bus and a separated peripheral bus. To the external world the application specific interfaces are switched by an I/O pin multiplexer.

To the Flash / IDE interface following devices could be connected:

• SmartMedia
• Compact Flash
• NOR Flash
• NAND Flash
• MLC Flash
• Hard Disk Drive

To the SPI Interface following devices could be connected:

• MMC or SD cards

The GPIO interface could be used to drive

• LED displays
• LCD displays
• Buttons
• Switches

USB Interface

The USB interface is connected to both on-chip memory and peripheral bus. The USB physical interface provides connection to full and high speed USB up to 480Mb/second.

Battery and Power Interface

The battery and power interface is built out of four major blocks. There is a DC-DC converter controlled by three low resolution ADCs, and a battery charging unit. The forth component is a temperature protection unit.

Players

STMP 3400

• Samsung YP 55H > STMP 3400
• Rio Nitrus > STMP 3400
• iAudio4 > STMP 3400
• Philips Rush SA230 > STMP3411L

STMP 3500

• MPMan CS157 > SMTP 3504
• iPod Shuffle > STMP 3550 - IpodShuffle
• iAudio i5, G2, G3, U2, F1 > STMP 3520
• Cenix CMP-M5 > STMP 3507
• Creative MuVo >STMP 3520
• Creative Zen Nano >STMP 3520
• Creative Zen Stone > STMP 3550
• Dyne Tuny 11 (AKA Trekstor i.Beat p!nk ) > STMP 35xx
• Philips SA 177+ SA1100 +SA1300s + SA1200 > STMP 35xx
• Philips GoGear SA 31xx + 41xx +51xx > STMP 35xx - PhilipsGoGear3100Port
• Samsung YP-53 +YP-T6 > STMP 35xx
• Samsung YP-U1 +YP-F1 > STMP 3550
• Samsung YP-U2 +YP-F2 > STMP 3550
• RioForge , Rio Carbon > STMP 35xx
• SanDisk Sansa e130/e140 > STMP 35xx
• Packard Bell Vibe 360 > STMP35xx
• iBead 400 (AKA Trekstor i.Beat organix) + iBead 600 (AKA Trekstor i.Beat sweez) >STMP 3520 - TrekStorIBeatOrganixFM
• Median Mcody MX300, MX700 > STMP 3520
• Median Mcody M20, M22, M25 > STMP 3507
• Median Mcody M30 (AKA Trekstor i.Beat Blaxx ) > STMP 3507
• Meizu X2, E2 (AKA Emgeton E2 Cult) > STMP3520
• Mobiblu DAH-1500i > STMP3520 - MobibluPort

Product Briefing

STMP 3600

• Samsung YP-Z5 > STMP 3650
• Creative Zen V / Zen V plus > STMP 36xx (ref: http://www.epizenter.net/comment.php?comment.news.271)
• Trekstor Vibez > STMP 3650
• IXINg (Technonia) TM-S4 + IXINg Duo > STMP 3650
• Siren IV Edge > STMP 3600
• RAmos RM-650 > STMP 3650
• Sandisk Sansa Express > STMP 3630 - SansaExpressPort

STMP36xx Linux BSP
Product Briefing

STMP 3700

• Creative ZEN > STMP 3760 - CreativeZEN

Product Briefing

Unknown

• Gigabeat P > STMP3???
• Some no-name players labeled "S1 mp3". The STMP3 chips are not supported by the s1mp3.org open firmware.

Motorola DSP56004

The STMP3xxx specifications state that the embedded DSP chip is "DSP56004-compatible", however, it is unclear whether additional instructions have been introduced. Porting Rockbox to an architecture whose smallest addressable unit is 24 bits with inadequate compilers is going to be painful at best. Luckily, information on the chip series is very easy to come by -- more than enough to write or port a new compiler.

The DSP56004 is a 24-bit digital signal processor architecture from Motorola. Compilers for older series, including 560xx, 561xx, 563xx and 566xx are hard to come by; there are several incomplete ports of GCC, and a few open source assemblers, dating back to early 1990s. The 568xx series, however, has a freely downloadable IDE and an adequate-seeming port of GCC from 2004.

For more information, see MotorolaDSP56k.

Firmware

SigmaTel is offering an SDK for these series of chips for $12,000. The SDK includes full source code to a reference implementation MP3 player. It is unclear how many MP3 player firmwares are directly based on this SDK, but there is evidence of similarity. For example, the SDK includes implementations of MP3 and WMV decoders, which most STMP3-powered players exclusively support.

Gigabeat P

A firmware updater is available for the Gigabeat P: http://www.gigabeat.net/mobileav/audio/soft/inf_gbP_fw3020.htm

• it contains the updater itself for windows with all the drivers to connect the player to the computer
• and the updated files for the player: bootmanager.sb, updater.sb, hostrsc.bin, hostlink.sb, stmpsys.sb, resource.bin

SanDisk Sansa e100

A firmware updater for the Sansa e100 series is available here: http://www.sandisk.com/Retail/Default.aspx?CatID=1295

• The package includes an updater for Windows.
• The updated files for the player are included: bootmanager.sb, updater.sb, hostrsc.bin, hostlink.sb, stmpsys.sb, resource.bin

TrekStor i.Beat organix

The Trekstor firmware updater for i.Beat organix is available at http://www.trekstor.de/en/service/index.php. Select topic=MP3 players, the right product, and your language.

Philips Rush SA230

The firmware updater of the Philips Rush SA230 player includes an unencrypted/unsigned binary firmware image; additionally, the updater boots off of USB before writing any flash, making this a safe environment for hacking and testing on real hardware. The updater application, drivers and firmware files (resource.bin, booty.s, dcc.s, stmpsys.s, usbmsc.s) are available from Philips web site here