Design of the most popular embedded on-board compu

Design of embedded on-board computer

[Abstract] firstly, the on-board communication technology of several multinational companies is briefly introduced, and then the self-developed on-board embedded computer (Auto PC) is systematically described. The auto PC adopts the embedded processor Xscale based on Intel company, has built-in GPRS wireless communication module, extends the GPS module of global positioning system, and uses the embedded operating system windows to realize wireless access to the Internet; Data exchange and processing with in vehicle control module through CAN bus; Realize remote diagnosis through the monitoring center; Embedding GIS and GPS to realize vehicle self navigation; Hands free, caller ID function; Based on Windows Office software, realize remote office; Camera function; Multimedia entertainment and other auxiliary functions

key words: embedded on-board computer windows CE operating system GPRS distributed data processing global positioning system

1 introduction

on-board electronic devices are increasing at an alarming rate, including applications such as navigation systems, communication devices and on-board entertainment systems. Telematics combines communication and computer technology to provide information, communication and entertainment services for drivers and passengers. In order to stand out from the fierce competition, automobile manufacturers also continue to expand the consumer content and connectivity of their in car systems. Therefore, there is no doubt that the future of the automotive industry lies in accessing the network and connecting data - at any time, anywhere, through wireless access to the network, we can not only meet the needs of users anytime and anywhere, but also benefit automotive manufacturers. It can also provide customers with the best quality information services, so that they can communicate with the network at all times in the car, and get high-quality services anytime and anywhere. At the front end, through the IT solution technology used in cars, it has provided profits to automobile manufacturers; At the same time, the application of IT technology provides useful information to feed back to the back-end designers, reducing costs and bringing users products that meet their needs. Through wireless access, car users will become an integral part of the Internet, which has brought countless benefits to the whole society

the benefits brought to car users through wireless access include:

(1) self diagnosis to check excessive fuel or overflowing washer fluid, or excessive wear of brake pads, or provide driving routes

(2) entertainment and communication keep children quiet when there is a traffic jam on the road and keep in touch with their parents at home

(3) information helps provide real-time traffic conditions and the fastest route; Provide information about car failure service and repair shop before car failure. At the same time, provide emergency services to drivers in trouble, such as car theft, or need overhaul

(4) safety provides enhanced communication with the first aid and fault service center, and the vehicle protection system is more intelligent, thereby reducing unnecessary alarms

similarly, wireless access will bring the following benefits to automobile manufacturers:

(1) it was impossible to know more about customers in the past. It can track the mileage of the car after years of efforts, how users drive, the time spent on the car, the places visited, and the number of trips. All this information can be used in automobile design and service improvement to meet market demand

(2) the source of new profits provides users with automobile services, communication information and resale opportunities

(3) it can reduce the models that are not needed by the market and produce the number of cars that meet the needs of the market

(4) improve customer relationship management and promote customers' purchase

2 introduction to relevant on-board system products of foreign companies

there are a variety of computer telematics solutions in the current market, forming functions of different service contents and functions of different levels of the same content. Various feasible solutions are designed to meet the needs of different users. Moreover, this trend will be more obvious in the future. The relevant products available in the current market are shown in Table 1

3 information service platform system design

system components, including three main parts (see Figure 1):

vehicle terminal equipment (embedded vehicle computer)

network service provider

network platform monitoring center

Figure 1 system structure composition

the whole system adopts computer and industrial control technology, and realizes the control and coordination of the whole system through the combination of software and hardware technology, Make the whole system work automatically. The on-board terminal equipment adopts an industrial embedded computer to control the function modules in the vehicle, collect various data information in the vehicle, compress and package the data, and transmit it to the system monitoring center through the network service provider. The monitoring center analyzes and processes the data through the special supporting software, and then sends the instructions of the monitoring center to the on-board terminal through the network supplier to remotely monitor the vehicle, and provide vehicle maintenance, entertainment, navigation, communication and other services at the same time. This article only introduces the on-board terminal (Auto PC)

4 embedded on-board computer auto PC (on-board terminal device)

this device adopts an embedded system, which directly embeds the computer into the application system, and integrates computer software/hardware technology, communication technology and semiconductor microelectronics technology. Embedded system consists of embedded processor, embedded system hardware and embedded application software

4.1 function description

after research, the embedded on-board computer (Auto PC) we want to develop should have the following functions:

4.1.1 realize wireless data transmission and voice communication through GPRS module, that is, realize wireless access to the Internet and answer. By integrating the functions of Internet into the vehicle, people can browse, send and receive e-mail, etc. in the car, so that car consumers can easily and quickly enjoy richer new information services. The built-in GPRS module is used to realize wireless connection. GPRS is a high-speed and efficient wireless system, fully known as "general packet radio service", which is a new packet data transmission technology opened on the existing GSM network. It allows mobile users to send and receive data in packet mode, especially suitable for intermittent, sudden or frequent, small amount of data transmission, and also suitable for occasional large amount of data transmission, which is the characteristic of most interconnected applications. High speed transmission GPRS adopts packet switching technology, and the highest theoretical value of data transmission rate can reach 171.2kbps. The channel type used can be either DCH (special signaling channel) or TCH (traffic channel), but the actual speed may be different due to the limitation of coding and terminal

GPRS system with automatic switching also has the advantage that data transmission and voice transmission can be carried out at the same time or switched. In other words, users can receive voice while surfing on mobile. Using the language channel control program, through the control of the wireless module, combined with the multi-function handle or touch screen or voice call to complete the dialing, vehicle dialing, hands-free and other functions

4.1.2 data exchange and processing with the control module in the car

there are two kinds of buses in the existing Buick car, class 2 and can. Among them, the communication between engine power control module (ECM) and body electronic module (BCM) adopts calss 2 bus, while the data transmission between ECM and transmission control module (TCM) adopts can bus. However, due to the simple can communication (only twisted pair is required), fast speed (high-speed can reach 500kbit/s), strong noise resistance and high reliability (with error check). In the next few years, can bus will gradually replace class 2 bus. Therefore, auto PC adopts can bus to realize communication with on-board module

can is a form of multi master competitive bus. Instead of the traditional station address coding method, it encodes the data information, and can identify more than 2032 (2.0A) or 500million (2.0B) data blocks at most. Any node in the network can actively send information to other nodes in the network at any time, regardless of the master and slave. It is very suitable for the interconnection and communication between the electronic control units of modern vehicles. Therefore, auto PC can obtain a large amount of shared data through CAN bus and obtain engine operating parameters from ECM in time; Obtain body status information from BCM. At the same time, auto PC sends commands to control each module through the bus, controls the operation of the engine, and controls the status of doors and windows

4.1.3 remote diagnosis

auto PC obtains a large amount of vehicle condition information from each control module through the CAN bus, such as the data volume of relevant engine intake, exhaust, fuel supply and sensors, the status information of the transmission, and the relevant body status information, such as door status, window status, lamp status and other status information. Track the vehicle information from time to time, locate the vehicle position at the same time, and remind passengers in time if there is a fault. All these data collection packages are sent to the monitoring service center. The application analysis software can only be stored in the monitoring center because of its large amount of data and large space occupation, as well as to meet the requirements of multiple customers. After receiving these data packets, the monitoring center decompresses and releases the data, and obtains the fault information through the special software analysis code. If the cause of the fault is simple, the solution and steps are given, and the user can carry out it as required. If the problem is complex, due to the installation of GPS, the system gives the maintenance address and contact method closest to the fault vehicle, and the system automatically notifies the maintenance center of the current location, owner and vehicle number of the fault vehicle

the data transmission of the collected vehicle information and the monitoring center adopts distributed data processing, and adopts the distributed database system of the computing environment based on the client/server. Each terminal (Auto PC) requests the service program to provide services in the form of SQL through remote call (RPC), and the server (monitoring center) executes the required processing, and then returns the results to the terminal, The wireless network between the terminal and the server realizes seamless collaborative computing; In the whole system, tcp/ip protocol communication is used to ensure the consistency, integrity and availability of data distributed in each terminal of the network through data replication technology and two-stage delivery protocol

4.1.4 vehicle navigation system

the existing vehicle navigation systems generally include: Vehicle Independent Navigation and positioning system, vehicle integrated navigation and positioning system. The latter mainly includes gps/dr vehicle navigation system and gps/e-map (electronic map) navigation system. At present, most of the pre installed products on the car are in GPS/e-map mode. In China, global positioning system (GPS) technology has become increasingly mature, which can provide vehicle navigation and positioning information. However, the domestic basic geographic information storage (GIS) can not meet the demand, mainly because: the research and development started late; China is in the process of rapid development, and geographic information changes rapidly, so it cannot be updated in time

gps/e-map mode, there are two main ways to deal with e-map. One is to store the map on DVD; At the same time, it is combined with the entertainment system in the car. The other is WebGIS, that is, maps are stored in the monitoring center for immediate local download and update. The construction of cities such as Japan and South Korea has been gradually improved, and the road traffic has not changed much. Therefore, DVD maps are mostly used. Most vehicles with pre installed navigation system in China also adopt this mode. But the disadvantages are: because China is in the process of large-scale economic construction, the city is developing and changing rapidly, and the map is updated frequently, so DVD discs need to be replaced constantly. Therefore, the map mode of this system adopts WebGIS. At the same time, the system also embeds