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Low cost system architecture for CD data access in car navigation sets

IP.com Disclosure Number: IPCOM000009373D
Original Publication Date: 2002-Aug-20
Included in the Prior Art Database: 2002-Aug-20
Document File: 2 page(s) / 141K

Publishing Venue

Motorola

Related People

Peter Wiese: AUTHOR

Abstract

In car navigation systems the map data is usually coming from a CDROM. The CDROM drive is coupled to the host MCU via an IDE/ATAPI interface. Using an audio only CD drive with a simple serial interface the cost of the drive, the more simple wiring and the MCU without the parallel ATA interface will drive down the overall car navigation system cost. A car navigation system mainly comprises a GPS sensor for positioning, a velocity and a heading sensor for dead reckoning, a CDROM for mass storage of the map data, a display and a keyboard for the MMI and a MCU for the route calculation. These building blocks are usually complemented by a car radio or multimedia system.

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Low cost system architecture for CD data access in car navigation sets

Peter Wiese

In car navigation systems the map data is usually coming from a CDROM. The CDROM drive is coupled to the host MCU via an IDE/ATAPI interface. Using an audio only CD drive with a simple serial interface the cost of the drive, the more simple wiring and the MCU without the parallel ATA interface will drive down the overall car navigation system cost.

A car navigation system mainly comprises a GPS sensor for positioning, a velocity and a heading sensor for dead reckoning, a CDROM for mass storage of the map data, a display and a keyboard for the MMI and a MCU for the route calculation. These building blocks are usually complemented by a car radio or multimedia system. A typical diagram showing the realization on block level is described in drawing 1.

 

Drawing 1: Typical diagram of a car navigation system

The dashed line indicates the components inside the navigation system. The system pictured in drawing 2 looks very similar. The main differences are: The CDROM is now a simple audio CD-drive (1) with a serial digital audio output, which normally connects to a stereo audio DAC. The interfacing changes from a parallel 16 bit interface to a serial 3-wire interface (2), which is shared for audio playback and CD data decoding. The processor does only need to have a serial I²S audio interface (3) instead of the wide ATA interface. In order to extract the CD data blocks from the I²S stream the MCU need...