The File - Dec 16, 2008 - (Page 4)

Trends DSPs integrate automotive bus standards continued from page CAN uses the producer-consumer model for data exchange. The producer, illustrated as Node2 in figure 1, sends out the data as a multi-cast or broadcast message. Node1 and Node4 filters recognise the message identifier and let the message pass. The Node3 filter rejects the message. CAN supports arbitration, and therefore supports multiple masters on the bus. There is no need for a host or an external arbiter to give the bus control to one of the CAN modules. Modules transmit when the bus is free. If two nodes transmit at the same time, the conflict is resolved through an arbitration process called Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), which uses a message identifier. CAN supports a maximum baud rate of 1Mbps. CAN 2.0A has an 11-bit identifier called a standard frame. CAN 2.0B, alternatively, supports an extended frame that uses a 29-bit identifier. Figure 1: The communication concept of a controller area network. MOST standard Multimedia and telematics applications augment features and functionality in automobiles, but also increase complexity. These features require high bandwidths that are way beyond what can be supported by CAN, which has led to the emergence of MOST as the standard for infotainment communications. MOST offers an optimised architecture for the real-time transport of audio, video, data, and control—providing the backbone for modern infotainment systems. It not only defines the physical interconnections between the devices but also specifies the software framework and communication protocol, thus simplifying system design and development. MOST uses Plastic Optical Fibre (POF) as a physical medium and therefore has very good EMC properties. The basic architecture of the MOST network is a logical ring that transmits data from one de- Figure 2: The MOST ring of a multimedia system in an automotive. vice to the next (figure 2). All bus systems are interlinked by means of a central gateway, which transmits signals from one network to another. The MOST system uses either 44.1kHz or 48kHz sample rates for transmitting digital audio. The first generation was MOST25, supporting a baud rate of 25Mbps. The second generation supports a baud rate of 50Mbps hence the name MOST50. Though the sample rate does not change, the frame length can now be 1024bits. MOST150, the latest (third generation) specification, features an isochronous transport mechanism to support extensive video applications, as well as an Ethernet channel. Its high bandwidth can support transmission of multiple high definition (HD) video streams and high quality multi-channel surround sound. Technical challenges Testing a MOST system can be a challenging task. Because infotainment systems are functionally complex, it is important to ensure interoperability and functionality of control devices as early as possible. It is often the case that not all devices are available at the same time to implement and validate crosssystem functionality. Even while performing the system test with all integrated components, it is still a challenge to cover all possible conditions or situations that cannot be tested under laboratory conditions. There can still be some of those corner cases that often do not occur in the field but can lead to serious malfunctions. Most of the current functions and features in automotive require high performance DSPs. Today’s DSPs are equipped with on-chip CAN modules and slave MOST devices known as Media Local Bus (MLB). MLB is a serial port used for exchanging data with other slave devices or with a MOST INIC controller. The onchip integration of these modules helps reduce total system cost and speeds up the system integration process, thereby resulting in shorter design cycles. Online Converging consumer, automotive electronics PC architecture integrates media centre ‘on wheels’ EE Times-India | November 16-31, 2008 | www.eetindia.com http://www.eetindia.co.in/ART_8800544938_1800004_TA_6f9de118.HTM?ClickFromNewsletter_081216 http://www.embeddeddesignindia.co.in/ART_8800546578_2800004_TA_8aec8881.HTM?ClickFromNewsletter_081216 http://www.eetindia.com/STATIC/REDIRECT/Newsletter_081216_EETI02.htm?ClickFromNewsletter_081216

Table of Contents for the Digital Edition of The File - Dec 16, 2008

EETimes India - December 16, 2008
Contents
National Semiconductor
Data Plane Processing Challenges DSP
Design, Debug with DSPs
TES 2008, NCMIPMV '08, ICACT '08, VLSI Conferene 2009, ICETiC 2009

The File - Dec 16, 2008