Data storage system surpasses DVDs for advanced car navigation

Car navigation has established itself in the market with rapid increases in functionality, performance and a substantial ability to handle large data sets quickly. In the first type of GPS navigation system, a CD-ROM disk was used as the media for the storage device that contains programs and large map data.

But it became necessary to have many CD-ROMs to cover a whole country because of an increasing amount of map data and many kinds of related information. To cope with increased data, the appearance of larger capacity media raised high hopes for navigation systems. A new type of DVD navigation system was put on the market in 1997. Adopting a large volume DVD-ROM disk with 4.7 Gbytes in one layer and 8.5 Gbytes in two layers, one disk could contain map data and all related information. However, navigation systems have used up most of the capacity of DVD-ROM disks.

Taking a step to resolve this, we launched a new type of hard disk drive (HDD) navigation system. Before development, our team had researched the evolution of car navigation systems and what is appropriate for car audio. The objectives were to develop a hardware platform to enable high performance, reduce size and provide ways to decode music.

The navigation hardware platform consists of three major blocks: a CPU, an ASIC and a graphic display controller (GDC). In order to provide the environment to process a large amount of data quickly, we enhanced the speed of the CPU and bus to 60 MHz, and increased the memory size from 16 Mbytes to 32 Mbytes. We also designed an ASIC that has many peripheral functions and interfaces to other devices needed for the navigation system.

To connect third generation cellular phones, the ASIC implements USB connectivity. Our solution has internal memory for the USB host controller in the ASIC and it is possible to use this function also in an embedded system.

In order to draw maps quickly, we made a careful choice of a GDC with coordinate transformation and clipping functions. This choice was made because the latest car navigation system would need to draw maps using the bird's eye view, three-dimensional simplified buildings and multilevel crossings.

We adopted a new 2.5-inch HDD (10 Gbytes) drive as the storage device instead of the DVD-ROM disk. As a consequence of the high data access speed of HDD, the basic navigation abilities have been improved. The time required to search the route, the speed of map scrolling, and the response of voice recognition was improved. One of the most striking characteristics of this car navigation system is the music server function using a rewritable storage device.

The most common area for placement of the system is in the trunk or under a seat, with the display set up on the dashboard or audio space in the console. In order to keep this navigation system to within the 2 DIN audio space, the system unit of the car navigation system is fitted in a 1 DIN size, and the display, TV tuner, FM/AM tuner, and amp are all placed in a the second 1 DIN size space. We have achieved this smaller size by adopting a BGA type package for the ASIC and DSP, and through the use of a GDC that has internal DRAM memory within itself.

Digital signal processing technology is used to encode and decode music. Using a DSP and the HDD, we created an added function, a music server. With the capacity of the pre-installed 2.5inch HDD of 10 Gbytes and the navigation data using about 8 Gbytes, the music server capacity takes up the remaining 2 Gbytes in which 20 CD albums can be stored. This system also supports an extra 10 Gbytes of HDD, so if the extra HDD is installed, it is possible to download about 150 CD albums. The system currently uses MP3 technology for encoding and decoding music, but other possible encoding system could be implemented with the programmable DSP.

This article will be presented at ICCE in a paper titled "HDD Car Navigation System."