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SoC for low-cost STBs runs Linux

Dec 20, 2007 — by Jonathan Angel — from the LinuxDevices Archive — 9 views

STMicroelectronics (STM) has announced volume production of an SoC (system-on-chip) intended for standard-definition set-top boxes (STBs). Designed with an emphasis on low cost, the STi5202 uses the SH-4 core and supports Linux, the company says.

According to STM, the STi5202 is based on the STi7109 SoC first released in 2005. It employs the same architecture and is software-compatible, but omits that product's support for HD, HD-DVD, and BluRay. The SATA capabilities of the STi7109 have been dropped as well, leaving USB as the SoC's means of hard drive support.

Befitting an updated product, however, the STi5202 does add support for Flash video, DivX and videoconferencing standards, as well as the recently established Chinese AVS1-P2 Jizhun Profile 4.0 level (SD) video decoding standard, STM says. It also can support HD displays, albeit with an SD picture, via an optional HDMI (high-definition multimedia interface).

The STi5202 illustrated at the heart of a set-top box
(Click to enlarge)

As before, other supported codecs include VC-1 and AVC (advanced video codec). Microsoft's VC-1 codec is used in the WMV9 (windows media video 9) format, while AVC — also known as H.264, and as MPEG-4 Part 10 — is the increasingly popular standard maintained by the AVC Alliance and other standards bodies. The STi5202's integrated video decoder also supports MPEG-2.

The processor subsystem on the STi5202 SoC is based on the ST40 RISC CPU (which has an SH-4 core). According to STM, this is clocked at 266Mhz, offering features including a five-stage pipeline with delayed branch support, a floating-point unit that supports matrix operations, a debug port, and an interrupt controller.

The STi5202 integrates STM's fourth-generation security processor, which it says supports Windows Media DRM 10, as well as the SVP (secure video processor) standard, a project of the SVP Alliance. STM says support for these security schemes allows digital rights to be passed between consumer devices.

STi5202 block diagram
(Click to enlarge)

In addition to the integrated security processor, the STi5202 is said to include:

  • An audio decoder, supporting:
    • WMA-9, WMA-9 Pro, MPEG-1 layer I/II, MPEG-2 layer II, MPEG-2 AAC, MPEG-4 AAC LC 2-channel/5.1 channel MPEG-4 AAC+SBR 2-channel/5.1 channel, Dolby Digital EX, Pro Logic II, MLP (Meridian Lossless Packing) and DTS
    • PCM mixing with internal or external source and sample rate conversion
    • 6- to 2-channel downmixing
    • PCM audio input
    • Independent multichannel PCM output, S/PDIF output, and analog output

  • Transport filtering and descrambling

  • Graphics engine that supports dual displays (standard and enhanced definition
  • USB 2.0 host controller/PHY interface
  • DVI/HDMI output (optional)
  • modem
  • 10/100 Ethernet controller
  • Transport stream merger/router
  • Programmable transport interfaces (PTIs)
  • SD digital video input
  • 4 x UARTs, two of which can be used for smart card applications
  • A JTAG interface


The STB7109 is in volume production now, in a 27 x 27 PBGA package. In addition to Linux, it also supports Windows CE.

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