HD DVB-T/C IPTV STB Reference Design
 Customer
Semidevices, a Russian company specializing in OEM/ODM electronics production.
Objective
The project goal is to develop a reference design platform for a digital consumer set-top box solution. The reference design should support standard (SD) and high-definition (HD) DVB-T, DVB-C and IPTV video signals and play back the decoded stream on a television receiver. The reference design should be based on the STi7167 processor by STMicroelectroniñs. The set-up box targets the middle-end market segment. It should be manufactured in the minimal form factor. The embedded software should be based on the Linux operating system.
Promwad's engineering team performed the following tasks:
- chipset choice and cost optimization;
- BOM estimation for mass production;
- principal circuit development;
- PCB layout;
- prototypes manufacturing and debugging;
- demo software development.
Solution
The STi7167Â by STMicroelectronics is used as a key component of the set-top box. The processor’s main distinctive feature is that the video\audio decoders and the demodulator are placed on one chip, which helps cut the cost and the size of the final device. In addition to processors, STMicroelectronics produces a number of additional microchips and STB active components, covering practically the whole range of components required for digital set-top boxes, which considerably reduces the overall production cost of the device. Moreover, this company provides maintenance and full technical support at the device development stage. STMicroelectronics offers debugged solutions for Linux-based software.
Basic Requirements for the Platform
The set-top box should receive signals within the working frequency range of 174—863 MHz for DVB-T and 47—863 MHz for DVB-C, receive streaming broadcasts through the Ethernet, decode MPEG-2/4 video streams and send the decoded video to a television receiver. It is also essential that the device can record and play back media files from storage devices with USB and SATA interfaces. The output signal format is SD (720õ576), composite, with PAL modulation and HD digital output (up to 1920x1080). The set-top box is connected to a television receiver through the RCA connector (composite video output) and HDMI (digital video and audio output). The set-top box should be fitted with a push-button control panel and an IR receiver to receive commands from the remote control console.
Figure 1. Overall structure of the device
Figure 2. Structural circuit of the device
The STi7167 processor from STMicroelectronics has been selected for this project. STi7167 is fitted with hardware capabilities for video decoding (MPEG-2 ISO/IEC 13818 /MPEG-4 AVC H.264) and sound decoding as well as has an embedded DVB-T/C demodulator. The ST40 kernel, compatible with Linux, Windows CE and OS21, is responsible for STB user functionality. The chip includes a DAC for analog sound and video and a HDMI interface for digital sound and high-definition (HD) video. The device uses the STV6433 external microchip for analog video filtration and amplification and external operational amplifiers for analog sound amplification.
The set-top box is controlled through a push-button keyboard or remotely through an IR port.
While choosing a tuner for the project, a number of suppliers were considered, such as Philips, Earda, Selteka and Sharp. The manufacturer of the product was selected using the following criteria: the cost of the solution, Linux driver support and technical parameters for signal reception. Finally, Earda was selected as the supplier of a tuner for the project and the EDT-3032 module was used. The small form factor tuner has one supply voltage.
Two DDR2 microchips with a total space of 256 MB are used as program and data storage memory. The set-top box application is run from the external NAND Flash. The back panel has a USB 2.0 connector to connect an external reading device and an RJ45 Ethernet connector to receive IPTV streaming broadcasts. The set-top box also has a SATA connector to connect a hard disk to the device.
The set-top box can be used together with an active antenna (power supply for the active antenna is 5Â 75mA). In addition to a high-frequency input (used to receive DVB-T/C signals), the device is also fitted with a high-frequency input for set-top box series connection.
The printed-circuit board is made with one-side mounting, which helps cut its cost, also it is made in the minimal form factor. DDR2 and differential pair tracing is based on signal integrity and calculation of the required impedances.
Embedded Software
A number of embedded software components were adapted and fine tuned to demonstrate the distinctive features of the reference design board:
- U-boot;
- Linux 2.6.23.17 kernel;
- JFFS2 root file system;
- Linux demo application samples;
- RTOS OS21 demo application samples.
Demo applications cover the following functionality:
- 3D graphics demo;
- DVB-T/C reception and playback;
- playback of RTP and UDP streaming video broadcasts;
- transmission of RTP and UDP streaming video broadcasts from STB;
- IEEE 802.11(Wi-Fi) module stream video reception and transmission;
- dual channel video decoding;
- simultaneous recording and playback from a USB stick or a SATA drive;
- additional functionality demo (picture-in-picture (PiP), still picture and slideshow, subtitles, teletext).
Advantages
- Use of microchips by one manufacturer, which provides easier access to technical support.
- Minimal number of chips used in the basic configuration.
- Low cost in mass production
| Technologies |
STLinux, DVB-T/C, IPTV |
| Programming languages |
C, C++ |
| Development tools |
STWorkbench, gcc |
| Project management tools |
SVN, Dotproject, Mantis |
| Man-day |
180 man/days |
| Project execution period |
2 months |
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