基于超声波检测的倒车雷达设计（硬件设计） 中英文献

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1、 2007 级毕业（设计）论文 信息工程学院 系（院） 电子信息工程 专业 中英文献翻译 题 目 基于超声波检测的倒车雷达设计（硬件设计） 学 生 姓 名 班 级 2007电子信息工程 学 号 指 导 教 师 日 期 2011 年 03 月 21 日 教 务 处 订 制AT89C2051 Microcontroller Instructions1.1 Features Compatible with MCS-51 Products 2 Kbytes of Reprogrammable Flash MemoryEndurance: 1,000 Write/Erase Cycles 2.7 V t

2、o 6 V Operating Range Fully Static Operation: 0 Hz to 24 MHz Two-Level Program Memory Lock 128 x 8-Bit Internal RAM 15 Programmable I/O Lines Two 16-Bit Timer/Counters Six Interrupt Sources Programmable Serial UART Channel Direct LED Drive Outputs On-Chip Analog Comparator Low Power Idle and Power D

3、own Modes1.2 DescriptionThe AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with 2 Kbytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmels high density nonvolatile memory technology and is compatible with the industry standard

4、 MCS-51 instruction set and pinout. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.The AT89C2051 provides the following standard fea

5、tures: 2 Kbytes of Flash, 128 bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, a precision analog comparator, on-chip oscillator and clock circuitry. In addition, the AT89C2051 is designed with static logic for operatio

6、n down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt system to continue functioning. The Power Down Mode saves the RAM contents but freezes the oscillator disabling all other ch

7、ip functions until the next hardware reset.1.3 Pin Configuration 1.4 Pin DescriptionVCC Supply voltage.GND Ground.Port 1Port 1 is an 8-bit bidirectional I/O port. Port pins P1.2 to P1.7 provide internal pullups. P1.0 and P1.1 require external pullups. P1.0 and P1.1 also serve as the positive input (

8、AIN0) and the negative input (AIN1), respectively, of the on-chip precision analog comparator. The Port 1 output buffers can sink 20 mA and can drive LED displays directly. When 1s are written to Port 1 pins, they can be used as inputs. When pins P1.2 to P1.7 are used as inputs and are externally pu

9、lled low, they will source current (IIL) because of the internal pullups.Port 1 also receives code data during Flash programming and program verification.Port 3Port 3 pins P3.0 to P3.5, P3.7 are seven bidirectional I/O pins with internal pullups. P3.6 is hard-wired as an input to the output of the o

10、n-chip comparator and is not accessible as a general purpose I/O pin. The Port 3 output buffers can sink 20 mA. When 1s are written to Port 3 pins they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (

11、IIL) because of the pullups. Port Pin Alternate FunctionsP3.0RXD (serial input port)P3.1TXD (serial output port)P3.2INT0 (external interrupt 0)P3.3INT1 (external interrupt 1)P3.4T0 (timer 0 external input)P3.5T1 (timer 1 external input)Port 3 also serves the functions of various special features of

12、the AT89C2051 as listed below:1.5 Oscillator CharacteristicsXTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz crystal or ceramic resonator may be used. To drive the device

13、from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2. There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divideby-two flip-flop, but minimum and maximum voltag

14、e high and low time specifications must be observed.1.6 Special Function RegistersA map of the on-chip memory area called the Special Function Register (SFR) space is shown in the table below. Note that not all of the addresses are occupied, and unoccupied addresses may not be implemented on the chi

15、p. Read accesses. to these addresses will in general return random data, and write accesses will have an indeterminate effect.User software should not write 1s to these unlisted locations, since they may be used in future products to invoke new fea tures. In that case, the reset or inactive values o

16、f the new bits will always be 0.1.7 Restrictions on Certain InstructionsThe AT89C2051 and is an economical and cost-effective member of Atmels growing family of microcontrollers. It contains 2 Kbytes of flash program memory. It is fully compatible with the MCS-51 architecture, and can be programmed

17、using the MCS-51 instruction set. However, there are a few considerations one must keep in mind when utilizing certain instructions to program this device.All the instructions related to jumping or branching should be restricted such that the destination address falls within the physical program mem

18、ory space of the device, which is 2K for the AT89C2051. This should be the responsibility of the software programmer. For example, LJMP 7E0H would be a valid instruction for the AT89C2051 (with 2K of memory), whereas LJMP 900H would not.1. Branching instructions:LCALL, LJMP, ACALL, AJMP, SJMP, JMP A

19、+DPTRThese unconditional branching instructions will execute correctly as long as the programmer keeps in mind that the destination branching address must fall within the physical boundaries of the program memory size (locations 00H to 7FFH for the 89C2051). Violating the physical space limits may c

20、ause unknown program behavior.CJNE ., DJNZ ., JB, JNB, JC, JNC, JBC, JZ, JNZ With these conditional branching instructions the same rule above applies. Again, violating the memory boundaries may cause erratic execution.For applications involving interrupts the normal interrupt service routine addres

21、s locations of the 80C51 family architecture have been preserved.2. MOVX-related instructions, Data Memory:The AT89C2051 contains 128 bytes of internal data memory. Thus, in the AT89C2051 the stack depth is limited to 128 bytes, the amount of available RAM. External DATA memory access is not support

22、ed in this device, nor is external PROGRAM memory execution. Therefore, no MOVX . instructions should be included in the program.A typical 80C51 assembler will still assemble instructions, even if they are written in violation of the restrictions mentioned above. It is the responsibility of the cont

23、roller user to know the physical features and limitations of the device being used and adjust the instructions used correspondingly.1.8 Program Memory Lock BitsOn the chip are two lock bits which can be left unprogrammed (U) or can be programmed (P) to obtain the additional features listed in the ta

24、ble below:Lock Bit Protection Modes(1) Program Lock BitsLB1LB2Protection Type1UUNo program lock features.2PUFurther programming of theFlash is disabled.3PPSame as mode 2, also verifyis disabled.Note: 1. The Lock Bits can only be erased with the Chip Erase operation1.9 Idle ModeIn idle mode, the CPU

25、puts itself to sleep while all the on-chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset.P1.0 and P1

26、.1 should be set to 0 if no external pullups are used, or set to 1 if external pullups are used.It should be noted that when idle is terminated by a hardware reset, the device normally resumes program execution, from where it left off, up to two machine cycles before the internal reset algorithm tak

27、es control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when Idle is terminated by reset, the instruction following the one that invokes Idle should not be one that wri

28、tes to a port pin or to external memory.1.10 Power Down ModeIn the power down mode the oscillator is stopped, and the instruction that invokes power down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power down mode is terminated. The

29、only exit from power down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.P1.0 and P1.1 shoul

30、d be set to 0 if no external pullups are used, or set to 1 if external pullups are used.1.11 Programming The FlashThe AT89C2051 is shipped with the 2 Kbytes of on-chip PEROM code memory array in the erased state (i.e., contents = FFH) and ready to be programmed. The code memory array is programmed o

31、ne byte at a time. Once the array is programmed, to re-program any non-blank byte, the entire memory array needs to be erased electrically.Internal Address Counter: The AT89C2051 contains an internal PEROM address counter which is always reset to 000H on the rising edge of RST and is advanced by app

32、lying a positive going pulse to pin XTAL1.Programming Algorithm: To program the AT89C2051, the following sequence is recommended.1. Power-up sequence:Apply power between VCC and GND pins Set RST and XTAL1 to GNDWith all other pins floating, wait for greater than 10 milliseconds2. Set pin RST to H Se

33、t pin P3.2 to H3. Apply the appropriate combination of H or L logic levels to pins P3.3, P3.4, P3.5, P3.7 to select one of the programming operations shown in the PEROM Programming Modes table.To Program and Verify the Array:4. Apply data for Code byte at location 000H to P1.0 to P1.7. 5. Raise RST

34、to 12V to enable programming.6. Pulse P3.2 once to program a byte in the PEROM array or the lock bits. The byte-write cycle is self-timed and typically takes 1.2 ms.7. To verify the programmed data, lower RST from 12V to logic H level and set pins P3.3 to P3.7 to the appropiate levels. Output data c

35、an be read at the port P1 pins.8. To program a byte at the next address location, pulse XTAL1 pin once to advance the internal address counter. Apply new data to the port P1 pins.9. Repeat steps 5 through 8, changing data and advancing the address counter for the entire 2 Kbytes array or until the e

36、nd of the object file is reached.10. Power-off sequence: set XTAL1 to L set RST to LFloat all other I/O pins Turn Vcc power offData Polling: The AT89C2051 features Data Polling to indicate the end of a write cycle. During a write cycle, an attempted read of the last byte written will result in the c

37、omplement of the written data on P1.7. Once the write cycle has been completed, true data is valid on all outputs, and the next cycle may begin. Data Polling may begin any time after a write cycle has been initiated.Ready/Busy: The Progress of byte programming can also be monitored by the RDY/BSY ou

38、tput signal. Pin P3.1 is pulled low after P3.2 goes High during programming to indicate BUSY. P3.1 is pulled High again when programming is done to indicate READY.Program Verify: If lock bits LB1 and LB2 have not been programmed code data can be read back via the data lines for verification:1. Reset

39、 the internal address counter to 000H by bringing RST from L to H.2. Apply the appropriate control signals for Read Code data and read the output data at the port P1 pins.3. Pulse pin XTAL1 once to advance the internal address counter.4. Read the next code data byte at the port P1 pins. 5. Repeat st

40、eps 3 and 4 until the entire array is read.The lock bits cannot be verified directly. Verification of the lock bits is achieved by observing that their features are enabled.Chip Erase: The entire PEROM array (2 Kbytes) and the two Lock Bits are erased electrically by using the proper combination of

41、control signals and by holding P3.2 low for 10 ms. The code array is written with all 1s in the Chip Erase operation and must be executed before any non-blank memory byte can be re-programmed.Reading the Signature Bytes: The signature bytes are read by the same procedure as a normal verification of

42、locations 000H, 001H, and 002H, except that P3.5 and P3.7 must be pulled to a logic low. The values returned are as follows.(000H) = 1EH indicates manufactured by Atmel (001H) = 21H indicates 89C2051Programming InterfaceEvery code byte in the Flash array can be written and the entire array can be er

43、ased by using the appropriate combination of control signals. The write operation cycle is self-timed and once initiated, will automatically time itself to completion.All major programming vendors offer worldwide support for the Atmel microcontroller series. Please contact your local programming ven

44、dor for the appropriate software revision.Ultrasonic ranging system designPublication title: Sensor Review. Bradford: 1993. Vol. ABSTRACT：Ultrasonic ranging technology has wide using worth in many fields，such as the industrial locale，vehicle navigation and sonar engineeringNow it has been used in le

45、vel measurement，self-guided autonomous vehicles, fieldwork robots automotive navigation，air and underwater target detection，identification，location and so onSo there is an important practicing meaning to learn the ranging theory and ways deeply. To improve the precision of the ultrasonic ranging sys

46、tem in hand，satisfy the request of the engineering personnel for the ranging precision，the bound and the usage，a portable ultrasonic ranging system based on the single chip processor was developedKeywords：Ultrasound r，Ranging System，Single Chip Processor1.IntroductiveWith the development of science

47、and technology, the improvement of peoples standard of living, speeding up the development and construction of the city. urban drainage system have greatly developed their situation is constantly improving. However, due to historical reasons many unpredictable factors in the synthesis of her time, t

48、he city drainage system. In particular drainage system often lags behind urban construction. Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon. It brought to the city sewage, and it is clear to the city sewage and drainage culv

49、ert in the sewage treatment system. comfort is very important to peoples lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core. Control System is the core c

50、omponent of the development of ultrasonic range finder. Therefore, it is very important to design a good ultrasonic range finder.2. A principle of ultrasonic distance measurement 2.1 The principle of piezoelectric ultrasonic generator Piezoelectric ultrasonic generator is the use of piezoelectric cr

51、ystal resonators to work. Ultrasonic generator, the internal structure as shown, it has two piezoelectric chip and a resonance plate. When its two plus pulse signal, the frequency equal to the intrinsic piezoelectric oscillation frequency chip, the chip will happen piezoelectric resonance, and promo

52、te the development of plate vibration resonance, ultrasound is generated. Conversely, if the two are not inter-electrode voltage, when the board received ultrasonic resonance, it will be for vibration suppression of piezoelectric chip, the mechanical energy is converted to electrical signals, then i

53、t becomes the ultrasonic receiver. The traditional way to determine the moment of the echos arrival is based on thresholding the received signal with a fixed reference. The threshold is chosen well above the noise level, whereas the moment of arrival of an echo is defined as the first moment the ech

54、o signal surpasses that threshold. The intensity of an echo reflecting from an object strongly depends on the objects nature, size and distance from the sensor. Further, the time interval from the echos starting point to the moment when it surpasses the threshold changes with the intensity of the ec

55、ho. As a consequence, a considerable error may occur Even two echoes with different intensities arriving exactly at the same time will surpass the threshold at different moments. The stronger one will surpass the threshold earlier than the weaker, so it will be considered as belonging to a nearer ob

56、ject.2.2The principle of ultrasonic distance measurement Ultrasonic transmitter in a direction to launch ultrasound, in the moment to launch the beginning of time at the same time, the spread of ultrasound in the air, obstacles on his way to return immediately, the ultrasonic reflected wave received

57、 by the receiver immediately stop the clock. Ultrasound in the air as the propagation velocity of 340m / s, according to the timer records the time t, we can calculate the distance between the launch distance barrier (s), that is: s = 340t / 2 3.Ultrasonic Ranging System for the Second Circuit Desig

58、n System is characterized by single-chip microcomputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, single-chip selection of 8751, economic-to-use, and the chip has 4K of ROM, to facilitate programming. Circuit schematic diagram shown in Fi

59、gure 2. Figure 1 circuit principle diagram3.1 40 kHz ultrasonic pulse generated with the launch Ranging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40, its operating voltage of the pulse signal is 40kHz, which by the single-chip implementation of the following procedures t

60、o generate. puzel: mov 14h, # 12h; ultrasonic firing continued 200ms here: cpl p1.0; output 40kHz square wave Ranging in front of single-chip termination circuit P1.0 input port, single chip implementation of the above procedure, the P1.0 port in a 40kHz pulse output signal, after amplification tran

61、sistor T, the drive to launch the first ultrasonic UCM40T, issued 40kHz ultrasonic pulse, and the continued launch of 200ms. Ranging the right and the left side of the circuit, respectively, then input port P1.1 and P1.2, the working principle and circuit in front of the same location. 3.2 Reception

62、 and processing of ultrasonic Used to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the op-amp amplification IC1A and after polarization IC1B to IC2. IC2 is locked loop with audio decoder chip LM567, internal voltage-controlled

63、 oscillator center frequency of f0 = 1/1.1R8C3, capacitor C4 determine their target bandwidth. R8-conditioning in the launch of the carrier frequency on the LM567 input signal is greater than 25mV, the output from the high jump 8 feet into a low-level, as interrupt request signals to the single-chip

64、 processing. Ranging in front of single-chip termination circuit output port INT0 interrupt the highest priority, right or left location of the output circuit with output gate IC3A access INT1 port single-chip, while single-chip P1.3 and P1. 4 received input IC3A, interrupted by the process to identify the source of inquiry