Engineering Project Management(2)Course paperTitle:Specialty：Taxi meterClass：H1303Name：Han TongLi XinhaoStudent ID：13109205161310920517CATALOG一、INTRODUCTION (1)二、OVERALL DESIGN SCHEME (2)（一）、S OFTWARE AND HARDWARE FLOW CHART (4)（二）、S OURCE PROGRAM DESIGN AND HARDWARE INTRODUCTION (6)2.1 8086 minimum system module (7)2.2 Chip 8255A (8)2.3 Chip 8253 (10)2.4Programmable control chip 8259A ............. 错误!未定义书签。
（三）、P ROBLEMS ENCOUNTERED ......................... 错误!未定义书签。
三、SUMMARY AND EXPERIENCE ........................ 错误!未定义书签。
四、REFERENCE： (15)APPENDIX .......................................... 错误!未定义书签。
一、IntroductionTaximeter is both passengers and drivers of the trade standards, it is an important symbol of the development of the taxi industry, is in a taxi is the most important tool. It is related to the interests of the parties to the transaction. With good performance of the meter whether is very necessary for the majority of taxi drivers or passengers. Therefore, the automobile valuation of is an application value.Our country in the 1970s began to taxi, but then the billing system mostly imported not only accurate, price is also very expensive. With the deepening of reform and opening up, the development momentum of the taxi industry has been very prominent, the domestic machinery manufacturers have launched domestic meter. Taxi valuation functions from at the beginning of the show only away (the driver himself pricing, calculated after four homes in five), to independent billing, and now can play an invoice and a voice prompt, according to time independent changes in price function. With the development of urban tourism, the taxi industry has become the city's window, a symbol of the civilization of a city Degree.With the development of the taxi industry, the taxi is an importantpart of urban traffic, starting from strengthening the industry management and reduce disputes of driver and passenger, with good performance meter to taxi drivers and passengers are very necessary. We design the 8086 based controller, to a44e Hall sensor location, on the taxi multifunctional pricing design, the output of the 8 digital tube display. 二、Overall design schemeBy 8253 as timer / counter, motor speed and measurement of motor speed control; 8255 as input and output interface, control digital tube display after the start mileage (after the decimal point from two effective value).Hardware connection description:Based on the DC motor controller, a motor speed measurement circuit is added.B the 8255 port as digital tube stroke code driven; the low four bits of aC port as the segment code control, showing the actual mileage. At the same time, also for the keyboard output column scan code; PC6 and PC7 input line scan code for the key identification, procedure using only the PC6 four buttons, which is defined as follows:X1: start / stop button; X2: accelerator key, and X3, X4 key combination to use; X3: "+" button; X4: "-" key.A mouth only uses the PA0, the output PWM pulse signal, by driving the motor, the output voltage is proportional to the duty cycle of the PWM pulse.The number of revolutions of the motor, through the hall element transformation for pulse number, into the 8253 passage 2, counting, speed is converted to mileage, the smallest unit is 0.01 km, send the recorded CPU. The results by the digital tube display.（一）、Software and hardware flow chartMain program flowstream（二）、Interrupt routineMileage counter interrupt routineWhenever Hall sensor outputs a low level signal makes a break, when the mileage counter on the mileage pulse meter over 1000 times, enter the mileage count the interrupt service program, mileage variables plus one. The main function of the total amount also correspondingly changes.Interrupt routineIn the middle of the pending interrupt program, 1ms each generate an interrupt, the current mileage value into a variable cache, every 5 minutes will be variable cache value and current mileage values compared when stop the car, the hall sensor for 5 minutes without signal output, current mileage value cache and variable quantity of the same value, then enter the waiting time, every 5 minutes to remember a price.Display programProcedures for the use of timer 1ms per generated once interrupted, the corresponding variable set, light a digital tube display a data display, recycling within the main function, realize the dynamic scan display, also according to the afterglow of the human eye and the persistence of digital tube, you can achieve the display.Keyboard programKeyboard using the way of inquiry, in the main program, when no key is pressed, the cycle of the main program, once the right button is pressed, they turn to the corresponding subroutine to deal with the end of the treatment to return.2.1 8086Minimum system module1、8086CPU constitute the system block diagram：2.2 Chip 8255A1、The role of 8255AIn this experiment, we use 8255A to transfer the digital quantity of analog quantity to CPU., and 8255 to control the work of ADC0809 by way of inquiry work..8086 sends control signals through 8255 to seven LED displays.2、Function analysis of 8255A8255A is parallel programming interface, can according to external conditions (I / O devices need to signal lines and it can provide the state line) to enable the various interface circuit.8255A internal three data port, namely port a, B, C a port port have three modes: mode 0, type 1 and type 2, and port B can only work in mode 0 or 1, and C usually as contact signal is used. In this experiment, the control word design 80h, initialization 8255, the port B, C as output.In three kinds of work, this design uses only mode 0, 0 is the basic input / output, in this way, three ports can by the program specified input / out of the way, but not both as input as output, did not provide a fixed contact network signal C divided into two four, four high and low four bits can be respectively arranged for input or output.3、Technical parameters of 8255A8255A pin signalSelect signal active, lowCS:Chip;A0:, address signal. A1PC JP52: port;PB JP53: port;1）Connected to a peripheral device.PA7~PA0：A port data signal line；PB7~PB0：B port data signal line；PC7~PC0：CPort data signal line；2）Connected to CPURESET: the reset signal. When this signal comes, all registers are cleared. At the same time three data ports are automatically set to the input port.D7~D0: they are connected to the 8255A data line and the system bus.CS: chip select signal. In the system, general according to all the interface chip to allocate at low address (such as the A5, A4, A3) composed of various chip select code. When the address consists of a low level, on 8255A is selected. Only when available, the signal read and write to the 8255 for reading and writing.RD: read the signal. When this signal is valid, the CPU can read data from the 8255A.WR: write a signal. When this signal is valid, CPU can write data to the 8255A.A0, A1: port selection signal.8255A has 3 data ports and 1 control ports, a total of 4 Ports:A1, A0 is 00, select the A port;A1, A0 is 01, select the B port;A1, A0 is 10, select the C port;A1, A0 11, select the control port.4、8255A mode control word8255A control word has two kinds: one is the way to select the control word, the other is the C port to press the position / reset control wordMode select control wordFigure 1 8255A control tableC port position / reset control wordchart2 8255A set / control table2.3 Chip 82531、8253 function analysisNMOS Intel8253 process is made of programmable counter / timer, there are several types of chip models, external pins and functions are compatible, but the work of the maximum count rate is different, such as 8253 (2.6MHz), 8253-5 (5MHz) Chip 8253 has three counters, were to become counter 0, counters 1 and 2, their bodies are completely the same. Input and output of each counter decided to to set in control register the control word, between each other to work completely independently. Each counter by three of the pins and the external contact and a clock CLK input and a gating signal input end of the gate, another output terminal out. Each internal counter is a 8 bits of the control register and a 16 bit count initial valueregister Cr, a count execution component CE and an output latch application Actuator is actually a 16 bit subtract counters, the initial value is the value of the initial value register, and the initial value register value is set by the program. The output latch Latch value is set by the program. The output latch ol is used to latch the count execution component Ce content, so that the CPU can be this read operation. Incidentally, Cr, CE and ol are 16 bit register, but can also for 8-bit registers to use 18253 role2、8253 pin signalCS：Chip select signal, activelow;A1, A0: address signal;2.4 programmable control chip 8259APrinciple of 8259AA piece of 8959A eight interrupt request line IR0~IR78259A by the operating system initialization, you can receive interrupt signal.8259A from the IR request line an interrupt signal, each request line a triggerto keep the request signal, so as to form the interrupt request register (IRR). At the same time, if the interrupt request signal line not be shielded, 8259A to CPU issued int signal, an interrupt request. At this time, if the CPU is in the allowed the interrupt status, the CPU will send inta signals to the 8259A enter the interrupt response time. If there is more than one letter of request , arriving at the same time, 8259A priority circuit will be priority selection for each request, the request of the highest priority in the interrupt response cycle and sent to interrupt service register (ISR) will it set, and reset the IRR of the corresponding bit. Then CPU again send a inta pulse to the 8259A, start another interrupt the corresponding period.8259A in the corresponding period to the data bus d0-d7 input an interrupt vector CPU according to the vector of X4 value can be from interrupt entry address table (IDT) remove the interruptservice program entry address into the interrupt service Procedures. While 8259A if the work in the automatic end interrupt (AEOI) mode automatically so that the corresponding bit in the ISR reset, or need to issue a EOI command to reset the ISR.In PC-XT/AT old - fashioned generally use a piece of 8259A interrupt request signal. In most modern PC, usually with two 8259A as level even. The piece is master slave, due to master an interrupt request line needs to be connected to the slave int foot, with the actual use of the external interrupt number is 15 (8 * 2 - 1).8259A structure1, data bus buffer --D7 ~ D0Data bus buffer for the three state, two-way, 8 bit registers, the data line D7 ~ D0 and CPU system bus connection, constitute the CPU and 8259A between the transmission of information channel.2, read / write control logic --WR/WDThe read / write control logic is used to receive the read / write control signal and the port address selection signal of the CPU system bus, which is used to control the read / write operation of the 8259A internal register.3, cascade buffer / comparator8259A can operate on a single, also can work in a plurality of cascade, cascade hardware connection as shown in Figure 6.10. Cascade buffer /comparator to provide multi chip 8259A management and selection function, the main chip, for the rest of the from the film.4, interrupt control logicInterrupt control logic to follow the programmed management approach to interrupt, responsible for on-chip components for sending a control signal to the and sent to a CPU interrupt request signal int and receive loopback CPU interrupt response of inta signals, control 8259A disruption into state management.5, interrupt request register (request register interrupt, IRR)IRR is an 8-bit registers, used to record the external interrupt request. Which D7 to d0 respectively and external interrupt request signal ir7 ~ ir0 corresponds, when IRi (I = 0 ~ 7) request (level or edge triggered), IRR the corresponding bit Di is set to 1, in response to interrupts inta signals effectively di is cleared.6, interrupt service register (service register interrupt, ISR)Di impulse impulse response (IRi ISR is an 8-bit registers, used to record the current CPU is service interrupt flag. When the external interrupt I = 0 ~ 7) requested by the CPU to enter service by the CPU to the first interrupt response inta ISR in the corresponding bit di (I = 0 ~ 7) is set to 1, and the ISR is restored to the throne the 8259A interrupt closing decision. If the definition for automatic closing, by the CPU of the second interrupt response inta along will reset to 0; if the definition is not automatically end, the CPU sends to the end of interrupt command in its reset .7, interrupt mask register (mask register interrupt, IMR)IMR is an 8-bit registers, used to store ir7 ~ ir0 interrupt mask flag. Its eight mask bit D7 to d0 and external interrupt request ir7 ~ ir0 corresponding, for controlling IRi request is allowed to enter. When the IMR Di bit is 1, corresponding to the IRi request forbidden; when the IMR Di bit is 0, then allow a corresponding interrupt request to enter. It can be set by software or clear. By programming setting mask word, can change the original priority level.See Appendix for program codeThree, summary and experienceAs a automation's big three students, I think doing computer programming is very meaningful, and it is very necessary. During the university time has passed, most of our contact is professional class. We master English in the classroom is only theoretical knowledge of professional courses, how to exercise our ability to practice? How to apply what we learn professional basic course of theory knowledge to practice it? I want to do a similar course design is for us to provide a good platform for practice.The importance to learn professional course curriculum design in the curriculum design process, I feel the deepest undoubtedly access to a large number of design data. In order to make their design more perfect, access to this information is very necessary, but also essential. Secondly, in this design, we use the previously learned knowledge, such as: assembly language, analog and digital circuit knowledge. Although in the past have never been alone used them, but in the learning process with a problem I find efficiency is very high, this is me to do the curriculum design of a harvest. On the other, the curriculum design, let me feel the team. In the team, I Our mutual cooperation, on the course design, which is crucial, lack of every person will have an impact on our design. Also to be thanked the teacher when we meet with difficulties, giving our suggestions and encouragement. End of the two weeks of the course design, but from the middle school to knowledge will let me a lifetime. The resultsshow that the proposed analysis, solve problems and practical ability raise will benefit to me in the future learning, work and life.For a period of two weeks of graduation design is nearing completion, with the help of Teacher Liu and Wang cordial guidance and students. The design is accomplished. On this to all give me the curriculum design guidance and help teachers and students to express the most sincere thanks:四、Reference1.Wu Xiuqing, Zhou Heqin < microcomputer principle and interface technology fourth edition >2.Zhou Changsen < electronic circuit computer simulation technology >3.Yang Suhang < microcomputer system principle and Application >appendix;Meter (using the speed controller to control the rotation of the motor, read the total mileage)DA TA SEGMENTT EQU 100 ;Timing cycle time (*T)T_HI DB 50 ;High level duration (*T_HI)NOW_T DB TNOW_HI DB 50T8253 EQU 609 ;Timer 8253 initial value =1.19M*0.512MS (basic cycle) =609RUN DB 0 ;Start stop signSPEED DW 0 ; MileageSTEP DW 50 ;10 meters of 8253 pulse number (that is, every 50 pulses, 10 meters ahead)TAB DB 3FH,06H,5BH,4FH,66H,6DH,7DH,07H,7FH,6FH ;0~9Display codeDISP DB 4 DUP (0),52H;Storage speedDA TA ENDSSTACK SEGMENT STACKDW 64 DUP(?) ;Define stack segmentSTACK ENDSCODE SEGMENT ;Code segment definitionASSUME CS:CODE,DS:DA TA ;Designated segmentSTART: MOV AX,DATAMOV DS,AXPUSH DS ;The current user DS segment into the stack to saveMOV AX,0000HMOV DS,AX ;Modify DS=0000H, point to the interrupt vector table where the segmentMOV AX,OFFSET IRQ0 ;Take out the entry offset address of the interrupt processing subroutine (in 0)ADD AX,2000H ;Fixed, actual address = load address offset + relative to the offset of the start of the 0MOV SI,0020H ;IR0 interrupt vector number 08H, in the vector table of the 20H~23HMOV [SI],AX ;Load offset address vector tableMOV AX,0000HMOV SI,0022HMOV [SI],AX ;Load segment address (0000H) into vector tableMOV AX,OFFSET IRQ7ADD AX,2000HMOV SI,0003CHMOV [SI],AX ;Load the offset address into the IRQ7 interrupt vectorMOV AX,0000HMOV SI,003EHMOV [SI],AX ;Load segment address (0000H) into vector tablePOP DS ;Recover user data segment DSMOV AL,13HOUT 20H,AL ;Write to ICW1MOV AL,08HOUT 21H,AL ;Write to ICW2MOV AL,01HOUT 21H,AL ;Write to ICW4MOV AL,7EH ;D7, D0 bit reset to 0OUT 21H,AL ;Write OCW1 (IMR); open IR7 8259A and IR0 interruptMOV AL,34H ;Set 8253 channel 0 working mode, 00110100BOUT 43H,AL ;CH0 uses the first to write low 8, after writing the high 8, the way 2, the binary countMOV AX,T8253 ;The initial value of the count is the basic cycleOUT 40H,AL ;Write to CH0MOV AL,AHOUT 40H,ALMOV AL,0B6H ;Set 8253 channel 2 working mode, 10110110BOUT 43H,AL ;CH2 first write low 8, after writing high 8 bit =0, 3, binary countMOV AX,STEPOUT 42H,ALMOV AL,AHOUT 42H,AL ;Write to CH2MOV AL,88H ;Write the way to control the word 8255A, set the way to work for 10001000BOUT 63H,AL ;A port mode 0 output, C port high 4 bit input, B port mode 0 output, CMouth low 4 bit outputMOV AL,00HOUT 60H,AL ;Off motorSTI ;Open interruptA1: MOV SI,OFFSET DISPMOV BL,2MOV AX,SPEEDA11: AND AL,0FHMOV [SI+3],ALAND AH,0FHMOV [SI+1],AHDEC SIMOV AX,SPEEDMOV CL,4ROR AX,CLDEC BLJNZ A11 ;The speed of the compression BCD code into a non compression code, into the bufferMOV SI,OFFSET DISPCALL DISPLAYMOV AL,00H ;Open switch scanOUT 62H,ALIN AL,62H ;Read C portAND AL,40HJZ A2 ;Key press, turn to read the keyboardJMP EXITA2: MOV AH,00H ;Record key scan codeMOV CX,04 ;Cyclic scan 4 timesMOV DL,77H ;Open the first line of the switch scan A21: INC AH ;Scan code +1ROL DL,1MOV AL,DLOUT 62H,AL ;Open a line of switch scanningIN AL,62H ;Read C portTEST AL,40H ;Take PC6 (Y1)JNZ A22 ;No key press, turnCALL DALEYCALL DALEY ;To shakeIN AL,62H ;Read C portAND AL,40H ;Take PC6 (Y1)JNZ A22 ;,CMP AH,2JNZ RELEA ;Is not to accelerate the key, turn (press theaccelerator key alone is invalid)OR AH,80H ;Is the accelerator key, the D7 bit =1JMP A22RELEA: CALL DISPLAYMOV AL,DLOUT 62H,ALIN AL,62HAND AL,40H ;Wait key releaseJZ RELEAJMP A23 ;AHSave scan code, =1 (X1 key press) start stop, =2 acceleration, =3'+', =4'-' key A22:LOOP A21JMP EXITA23: MOV AL,AHAND AL,0FHCMP AL,01HJNZ A3 ;Not press the start and stop button, then turnMOV AL,RUNTEST AL,01HJNZ A24 ;From start to stopMOV RUN,01 ;Set flagMOV NOW_T,T ;Reload time cycleMOV AL,T_HIMOV NOW_HI,AL ;Reload high level timingMOV SPEED,00 ;Re valuation (mileage)JMP EXITA24: MOV RUN,00 ;Reset start flagMOV AL,00HOUT 60H,AL ;Off motorJMP EXITA3: MOV AL,AHAND AL,0FHCMP AL,03JNZ A6 ;Not '+' button, turnMOV BL,1TEST AH,80HJZ A4 ;Did not press the accelerator keyMOV BL,10 ;Press the accelerator key, plus 10, plus 1.A4: ADD BL,T_HICMP BL,100JBE A5MOV BL,100A5: MOV T_HI,BL ;The percentage increase can not be >100% JMP EXITA6: MOV AL,AHAND AL,0FHCMP AL,04JNZ EXIT ;Not turn - keyMOV BH,01TEST AH,80HJZ A7 ;Did not press the accelerator keyMOV BH,10 ;Press the accelerator key, -10, normal -1 A7: MOV BL,T_HISUB BL,BHJNC A8MOV BL,00A8: MOV T_HI,BL ;The minimum percentage was 0%EXIT: JMP A1;IR0 8259A interrupt processing subroutine (8253 of the CH0 timer basic cycle 0.512MS) IRQ0: PUSH AXSTIMOV AL,RUNAND AL,ALJZ IREXIT ;Does not start, then the test speedMOV AL,NOW_TSUB AL,1JNZ IRSP1MOV NOW_T,T ;Reload time cycleMOV AL,T_HIMOV NOW_HI,AL ;Reload high level timingJMP IREXITIRSP1: MOV NOW_T,AL ;High duration to, the PA0 output is 0 MOV AL,NOW_HITEST AL,ALJNZ IRSP2MOV AH,00H ;High duration to, the PA0 output is 0JMP IRSP3IRSP2: SUB AL,1 ;High level duration less thanMOV NOW_HI,AL ;Value after saving -1MOV AH,01H ;PA0 output is 1, high levelIRSP3: MOV AL,AHOUT 60H,ALIREXIT: MOV AL,20H ;EOI interrupt routineOUT 20H,AL ;Write OCW2 8259ACLIPOP AXIRET ;Interrupt return;IR7 8259A interrupt processing subroutine (8253 CH2 count interrupt, 10 m)IRQ7: PUSH AXSTIMOV AX,SPEEDADD AL,01DAAXCHG AL,AHADC AL,00DAAXCHG AL,AHMOV SPEED,AXMOV AL,20H ;EOI interrupt routineOUT 20H,AL ;Write OCW2 8259ACLIPOP AXIRET ;Interrupt return;DISPLAY:PUSH AXPUSH BXPUSH CXPUSH DXPUSH SIMOV CX,4MOV DL,7FHMOV SI,OFFSET DISPMOV BX,OFFSET TABDISP1: ROL DL,1MOV AL,[SI]XLAT ;Lookup table to display codeTEST DL,02HJNZ DISP2 ;Is the second digit display?OR AL,80H ;Yes, add the decimal point. DISP2: OUT 61H,ALMOV AL,DL ;Allows X1, X2, X3, X4 (PC3~PC0) digital control in turnOUT 62H,ALCALL DALEYINC SILOOP DISP1 ;Four cycles, display speedXOR AL,ALOUT 61H,AL ;Guan XianshiPOP SIPOP DXPOP CXPOP BXPOP AXRET; time delay subroutine ；wait subroutineDALEY: PUSH CXMOV CX,0560H ;Internal cycle timesDALEY1:LOOP DALEY1 ;0560H times, to complete the delay POP CXRETCODE ENDSEND START。
