Abstract: This article proposed the embedded Chinese obviously terminal design proposal, involves one kind of vehicle to carry the satellite positioning system, carries the localization information which and the GSM/GPRS wireless communication function through the serial port correspondence using the vehicle the GPS terminal provides realizes the real time display localization information, the vehicle to carry functions and so on telephone, short information and voice prompt, achieves the man-machine interaction the goal, simultaneously unifies the central software also to be able to realize the vehicles dispatch function well.
Key word: GPS; Embedded; Chinese obviously terminal; Serial port correspondence
1 introduction
In the last few years, the GPS guidance localization technology is developing unceasingly, more and more vehicles installed the vehicle to carry the GPS terminal. At this point, the vehicle carries the GPS terminal already to become the municipal transportation management network the important component. But since continuously, user after having installed the vehicle carries the GPS terminal, because lacks the friendly man-machine interaction equipment, has affected the user use and the vehicle carries the GPS terminal the popularization, limited the vehicle to carry the GPS terminal product the function expansion. Through the addition Chinese character alphanumeric display terminal, can cause the user more convenient use vehicle to carry the GPS terminal, the convenient center carries on the dispatch management, makes up the beforehand product the insufficiency.
2 embedded Chinese’s compositions obviously
Figure 1 the vehicle carries the GPS system structure drawing
The embedded Chinese’s function obviously is mainly carries the terminal and the mileage fare meter correspondence through the serial port and the GPS vehicle, the receive processes the GPS vehicle to carry the related operation data which the terminal transmission the GPS framing signal and the mileage fare meter transmit, and lets the user through the infrared remote control and the pressed key obviously carry on the establishment and the operation to the Chinese, then in the liquid crystal module demonstrated that the corresponding content, and can provide the pronunciation service.
The embedded Chinese obviously is composed of the following several parts: Chinese obviously motherboard, liquid crystal module, infrared receive, pressed key, loudspeaker, light emitter diode as well as coupling.
3 motherboard hardware part
The embedded Chinese’s motherboard obviously is composed of the following several parts: And mouth Flash, feed circuit, LCD module connection and driving circuit, serial port communication circuit, watch-dog electric circuit and speech chip and power amplifier electric circuit.
Figure 2 Chinese obviously structure drawing
3.1 MSP430 series monolithic integrated circuit
The MSP430 series monolithic integrated circuit is 16 monolithic integrated circuits which develops by TI Corporation, its prominent characteristic is the ultra low power loss, requests the low situation very suitably in each kind of power, is the present field all interior integration dodges the fast memory (Flash ROM) in the product the power loss to be lowest, the consumption power is only other dodges the fast microprocessor (Flash MCUs) 1/5. It consumes the copper current under the 3V working voltage to be lower than 350uA/MHz, waits for an opportunity the pattern is only 15 uA/MHz, has five kind of energy conservation patterns. Its 64K procedure space had guaranteed may hold the enough word length, but in the program execution may write internal FLASH may use in depositing the central number, the telephone number and the GPS vehicle carries the terminal establishment and so on important data. In the monolithic integrated circuit has the anti-ESD protection, has the strong antijamming ability. The online programming, the procedure renewal is convenient. The simulator structure is simple, may manufacture voluntarily. This series technical grade monolithic integrated circuit operating temperature scope for the - 40~ 85 degrees Celsius, may satisfy the vehicle to carry the equipment application request.
3.2 feed circuits
For compatible different Che Zai the storage battery provides 12V and the 24V voltage, the feed circuit uses the voltage changer ought to be able to satisfy may the input voltage in 9V to 36V between. Because the vehicle carries the environment to be worse, the storage battery supply variation is big, to prevent the big electric current which the exterior disturbance causes to burn out the internal primary device, may from restore the fuse in the power source input end series. This design mentality motherboard’s basic power loss approximately about 50mA, when the LCD back light lightens, power loss about 180mA, therefore may select the fuse electric current in 350mA from restores the fuse to be possible to satisfy the request. In order to prevent the microprocessor or the monolithic integrated circuit because of the instantaneous pulse, if the electrostatic disturbance, causes the malfunction or the damage, may in the power source positive electrode input end parallel TVS tube, because the vehicle carries the storage battery power line voltage is 12V or 24V, therefore may act according to the actual situation selection.
Figure 3 feed circuit
3.3 memories
Flash needs to preserve the GPS localization information, the key point, the fonts, the telephone conversation record, the short information, the operation data and other data. The Flash capacity demand analysis is as follows:
3.3.1 fonts approximately need the 800K byte.
3.3.2 GPS localization information needs to preserve as the driving record, at present the overwhelming majority GPS module is each second transmits a GPS locator data, if each does not retain the too big practical significance as the driving record, therefore may every other one to ten minutes retain a locator data, like this 10000 may preserve about one week-long driving record at least, meets the practical application needs. The localization information includes: Time, longitude, longitude marking, latitude, latitude marking, speed, direction, condition as well as extra message and so on.
Localization information content computation: 10000 ×48 byte =480000 byte
3.3.3 regarding need the regulating prompt, the road section prompt, the region prompt and so on special demand, may through save these key points or the polygon locator data information in advance, in the vehicles travel process passes through, arrives, leaves these regions, will receive the localization information to and coordinates the pronunciation with it ratio to disseminate news then distinguishes and carries on the prompt. The key point information includes: Enters the key point time, to drive out of key point time, left bottom latitude, left bottom longitude, top left-hand corner latitude, top left-hand corner longitude, right bottom latitude, right bottom longitude, top right-hand corner latitude top right-hand corner longitude as well as other flag bit and so on.
Key point information content computation: 52 byte ×200 =10400 bytes (preserve 100 key points, reserves 100 key point capacities)
The polygon information includes: Information and so on apex serial number, apex longitude, apex latitude.
Polygon: 10 ×9 apex * (2 10 11)=2070 byte (preserves 10 9 side shapes most greatly)
Therefore the capacity should above 1MB, be supposed better to use and mouth correspondence Flash at least satisfies with the MSP430 series monolithic integrated circuit’s high speed data transmission.
3.4 speech chips and power amplifier electric circuit
In order to reduce the development cycle, may consider that used the processor interior to integrate the complete speech synthesis system. The speech chip which flies by the Science and Technology Institute of China news is an example, this chip support random Chinese text’s synthesis, Chinese code may use GB2312 or the Unicode two encoding methods, level logic is the TTL level, through the serial port (UART) receive superior machine transmission’s order and the data, the order and the data carries on the seal and the transmission take the frame way, the permission transmission data greatest length as 200 bytes. The speech chip after receiving the order or the text synthesis finished, through serial port TXD2 to MCU transmission feedback information. MCU may through the receive chip feedback, understand whether the chip has received the order correctly, as well as chip whether to have completed the text synthesis. When the chip READY signal foot is in the low level, indicated that the chip is at waits for an opportunity the ready state; When is in the high level, indicated that the chip is being at the text synthesis condition. The pronunciation through 10bit the DAC simulation audio frequency output, the periphery power amplifier electric circuit uses most commonly used LM386 the power amplifier electric circuit to be able to satisfy the request.
Figure 4 speech chip functional block diagram
3.5 other peripheral circuits
Because domestic present Che Zai the GPS terminal and the mileage fare meter basic are use the serial port correspondence the way connection Chinese character alphanumeric display terminal, therefore the basis does not take the same bus to carry the terminal and the mileage fare meter must use the corresponding serial port mailing address, may consider that uses transformation chip electric circuits, the electric current link electric circuit or other solution and so on MAX202. Electric current link circuitry following chart:
Figure 5 electric current link electric circuit schematic diagram
MCU and Flash should better use the 3.3V power supply the low power loss chip, therefore needs to connect with the LCD module through the 3.3V~5V level switch chip for the core driving circuit, may also use the appropriate solution according to the LCD module.
4 conclusions
Carries the GPS technology in the vehicle already very mature today, the vehicle carried the GPS system’s trend of development provides the friendlier man-machine interaction function, a more perfect service. The embedded Chinese character alphanumeric display terminal then realizes through the serial port to the vehicle carries the terminal the expansion, carries the GPS terminal for the vehicle to provide the friendly man-machine interaction contact surface, as well as the personalized establishment, facilitates the user greatly the use, moreover expanded the vehicle to carry the GPS terminal the function and the resources, could provide the richer service content for the user. Therefore, the embedded Chinese character alphanumeric display terminal will certainly to impel the vehicle to carry the GPS system’s popularization enormously, promotes the vehicle to carry the GPS system’s development.
Reference:
[1] Hu greatly programmable. MSP430 series 16 monolithic integrated circuit principles and application. Beijing: Beijing University of Aeronautics and Astronautics Publishing house, 2000
[2] Hu greatly programmable. MSP430 series FLASH 16 monolithic integrated circuits. Beijing: Beijing University of Aeronautics and Astronautics Publishing house, 2001
the [3] Beijing gathers the advantage science and technology Limited company. The mileage fare meter and the vehicle carry the terminal GPS communication protocol. Beijing: Beijing gathers the advantage science and technology Limited company, 2005
