The appearance of GPS 3D navigation maps is not accidental. 3D navigation displays more information than 2D. By realistically simulating the streets and intersections in the real world through 3D images, drivers can not only see detailed and realistic pictures and numbers. With hundreds of digital integrated positioning points, you can also see the simulation of the entire city and its surrounding areas, making it easier and easier to find the right direction at a difficult intersection, a strange city, and travel safer to your destination. Make navigation more intuitive and easier to drive. Therefore, 3D navigation will be the future direction of navigation technology development.
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3D navigation increases stability requirements
The emergence and promotion of 3D maps and maps of more information points have made large-capacity memories an important direction for the development of navigation products in 2008. The need for mass storage also comes from the need for data protection. At present, the navigation software and map data of many navigators are stored in the SD card. If the SD card is lost, the data is completely lost; and the SD card is used to store the navigation.
Software and maps have relatively limited protection for copyright. Therefore, some manufacturers choose to burn navigation software and maps directly into the built-in Flash to ensure the security of data and software.
Figure 1 Atlas III based GPS navigation hardware system solution
The choice of memory can affect the stability and reliability of the entire product. Some processors currently integrate MLC (Multi-Level Cell Flash) controllers, but we do not recommend using Embedded Raw MLC directly. Instead, we recommend using Managed NAND, such as iNAND, because Managed MLC is a professional memory vendor that will use MLC controllers and MLCs. The memory chips are integrated and a large number of hardware and software optimizations are performed. After a large number of production tests, it is provided to customers as a complete qualified product, with good reliability and better read and write performance (continuous reading: 10MB/s, continuous writing: 9MB/s), technology More mature.
At present, GPS navigation product memory mainly has two kinds of SLC (single layer unit flash memory) and MLC (multilayer unit flash memory). In terms of reliability, MLC has poorer read/write performance than SLC. SLC flash memory can be read and written about 100,000 times, while MLC can only read and write about 5,000 to 10,000 times. This puts high demands on the degree of optimization of MLC drivers and the adequacy of testing. In particular, to optimize the wear leveling rate algorithm, try to make the number of reads and writes of different blocks similar, thus extending the service life of the entire MLC. It is also extremely important to deal with the management of bad blocks. For audio and video playback, navigation software to read maps and other applications that need to read and write Nand flash frequently, if the MLC driver development is not properly developed or the test is not comprehensive, it is likely to cause the MLC bad block to increase rapidly during use, Flash available capacity is fast Reducing, eventually causing serious consequences such as data loss or even system crashes.
Such problems are gradually accumulated during the use of consumers, so it is difficult to find in the production test stage, and these fatal technical hazards can only be discovered when the products are in the hands of consumers. Therefore, when choosing an MLC solution, the reliability considerations must be cautious. In the read and write speed, the MLC read and write speed is slower than the SLC chip under the same conditions. The bottleneck of MLC in read and write speed will drag down the performance of the entire system. Especially for multimedia playback applications, if the reading speed is too slow, the playback may be discontinuous, and the sound image may not be synchronized. For navigation software, it appears that loading the map takes too long. These directly affect the consumer experience.
From the mainstream GPS navigation hardware solutions, there are two main solutions for using MLC at present: Embedded Raw MLC. The Raw MLC chip is directly used in the system, and the Raw MLC chip is driven by the MLC controller built in or external to the processor. Such a solution, developers need to integrate their own hardware, optimize the MLC driver to solve the problem of reliability and read and write speed. The advantage is that the cost is lower than other schemes; the disadvantage is that the read/write efficiency needs to be optimized (in the worst case, only 2MB/s), and the reliability is not guaranteed.
Managed Nand. Managed Nand is a professional memory vendor that integrates the MLC controller with the MLC chip and performs a number of hardware and software optimizations. After passing the mass production test, it is provided to the customer as a complete qualified product. Reliability is well guaranteed. Representative products are: SanDisk's iNand and Samsung's MoviNand. The advantage is efficient reading and writing (iNand continuous reading: 10MB / s, continuous writing: 9MB / s), the technology is mature and easy to use. The reliability of the product is guaranteed by the professional manufacturer; the disadvantage is that the cost is higher than the Embedded Raw MLC.
Although some of the PND's major international processors use integrated MLC controllers, they do not use the direct-fed Embedded Raw MLC solution. Instead, Managed Nand was chosen. Presumably, these big manufacturers also chose a more reliable and efficient Managed Nand after weighing the balance between cost and reliability. After all, for any responsible manufacturer, stability is overwhelming. An unreliable product, even if the cost seems to have an advantage, may not be converted into real profits. Quite the contrary, this can lead to irreparable losses.
For the same reason, Yuanfeng International and SiRF and Sandisk jointly launched the SiRF AtlasIII platform based on iNand. The PCBA navigation board developed by it is also based on this platform. In this platform, a 2Mb / 4Mb Nor flash is used to store the boot loader and registry information that needs to be modified frequently. Store data such as OS image and navigation software on iNand or directly on the SD Card. With this solution, not only can the large-capacity built-in Flash capacity be provided, but also the problem of system reliability reduction caused by the use of Embedded Raw MLC can be avoided.
The stability and reliability of the system also have a lot to do with the hardware and software design of the system. If the design is poor, there will be frequent crashes and the like, and in serious cases, the system will collapse, which will affect the consumer's use and result in large-volume returns. In particular, most of the current navigation products integrate audio and video player software and other application software. If some software has BUG, ​​it may cause system performance degradation, navigation path calculation is too slow, and maps cannot be updated in real time.
Figure 2 Yuanfeng multimedia navigation products YFN35C306-17C-3
Design considerations for hardware solutions
For GPS navigation products, hardware is always a part that cannot be ignored. The choice of processor and memory, the selection of GPS receiver components, the design of the power management section, and the development of embedded software determine the performance of the product. A little different from other consumer electronics products, design companies have become a prominent part of the GPS navigation industry chain. Focusing on the development of navigation product hardware, the design company provides a variety of complete solutions for the majority of OEMs to promote more mature and stable navigation products.
As a solution provider for many well-known GPS navigation brands, Yuanfeng International is currently promoting SiRF's SoC Atlas III solution, with a 400MHz ARM926 and 264MHz DSP dual-core processor, optimized 30-channel embedded GPS baseband and high-speed DDR200. Or the 166/133MHz SDR memory controller enables excellent GPS positioning, tracking, path search and smooth image display based on various solutions of the platform, and simultaneous music playback. The WINCE 5.0 software platform used by Yuanfeng International and the software tools such as AP3.0 enable users to experience a more user-friendly operation experience.
The continuous development of hardware has improved the performance and integration of GPS navigation products, and also effectively reduced the cost, increased the cost performance, and ensured better system scalability. For example, the increased processing power of the CPU's main frequency increases, making more applications possible, such as the operation of 3D navigation software and multimedia playback. The chip is upgraded from ARM9 to ARM11. The process is from 0.18um, 0.13um to 90nm, 65nm. The system performance is continuously improved, the power consumption is lower and the integration is higher. The development of antenna technology has also promoted the development of GPS navigation products. The size of the original 25 × 25 × 4mm, to the current 13 × 13 × 4mm evolution, does not reduce the sensitivity of the GPS signal, but through the technological innovation, the signal sensitivity of the entire system is effectively improved, greatly speeding up the signal capture speed . At the same time, the reduction in size also effectively increases system integration, making thinner and more stylish designs possible.
Conclusion
As a kind of consumer electronic products, GPS navigation products are going to integrate richer and higher quality digital content into more diversified products to realize organic connection of hardware, software, content and services. Especially in the field of design, more emphasis will be placed on personalization. Therefore, high-definition, 3D, high-storage, multi-functional, and intelligent navigation products have become the development trend.
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