CN202362457U

CN202362457U - Automobile distance detector based on single-chip microcomputer

Info

Publication number: CN202362457U
Application number: CN2011204929184U
Authority: CN
Inventors: 许世维; 余曼; 王旭; 孙家永
Original assignee: Changan University
Current assignee: Changan University
Priority date: 2011-12-01
Filing date: 2011-12-01
Publication date: 2012-08-01
Anticipated expiration: 2021-12-01

Abstract

The utility model discloses an automobile distance detector based on a single-chip microcomputer. The automobile distance detector comprises four ultrasonic sensor probes which are installed on a front bumper and a rear bumper of an automobile, the single-chip microcomputer, a drive receiving module circuit, a shaping, filtering and amplifying module circuit, a liquid crystal display (LCD) module and a buzzer. Ultrasonic waves are transmitted and echoes are received through the ultrasonic probes, the acquired data is transmitted to the single-chip microcomputer, the single-chip microcomputer calculates the distance between the automobile and an obstacle according to the acquired information, a safe distance limit is set in the single-chip microcomputer, and if the calculated distance is smaller than the limit, the single-chip microcomputer controls the buzzer to give out alarms, the distance between the automobile and the obstacle ahead is displayed on an LCD and a great help is provided for a driver to drive safely. The automobile distance detector based on the single-chip microcomputer has the advantages of low price, convenience in use and the like.

Description

A kind of SCM Based automobile is visited apart from appearance

Technical field

The utility model belongs to the automobile engineering field.Relating to a kind of is that the intelligent vehicle of controlling core is visited apart from appearance with the single-chip microcomputer, can detect the distance between automobile headstock and the barrier exactly, demonstrates the distance and the caution of sounding by display.

Background technology

Along with Chinese economic development, the raising of living standards of the people, automobile becomes the common consumer goods from previous luxury goods, gets into vast average family.But along with increasing of automobile quantity in the city, the automotive safety problem also more and more receives broad masses of the people's concern.And in numerous traffic hazards, cause owing to driver's driving level is limited knock into the back and scratch and in occupation of quite great proportion.Therefore, the driver that can help who designs a kind of lower cost, superior performance surveys preceding the spy apart from appearance of automobile of the place ahead barrier, for domestic low and middle-end car very high marketable value will be arranged.

Summary of the invention

The purpose of the utility model is, provides a kind of SCM Based automobile to visit apart from appearance, can detect the distance between automobile headstock and the barrier exactly, demonstrates the distance and the caution of sounding by display.

In order to realize above-mentioned task, the utility model adopts following technical scheme to be achieved:

Visit before a kind of SCM Based automobile apart from appearance; It is characterized in that; Comprise 4 ultrasonic sensor probes that are installed on the bumper of automobile front and back; 4 ultrasonic sensor probes are connected with the filtering amplification and rectification circuit through driving receiving circuit, and the filtering amplification and rectification circuit is connected with single-chip microcomputer, also is connected with LCD Liquid Crystal Module and hummer on the single-chip microcomputer.

Other characteristics of the utility model are:

Described ultrasonic sensor probe receives the ultrasonic sensor probe of integrated probe for emission.

Described single-chip microcomputer is the STC89C52 single-chip microcomputer.

Described LCD Liquid Crystal Module is 1602 type LCDs.

The SCM Based automobile of the utility model is visited apart from appearance; Adopt the ultrasonic ranging principle, receive integrated probe transmission ultrasound wave and accept echo, calculate the distance between headstock and the barrier by the emission that is installed on the headstock bumper; In safe distance boundary of single-chip microcomputer set inside; If the distance that calculates is lower than this boundary, single-chip microcomputer is then controlled the hummer sound that gives a warning, again by the display range of a signal and the caution of sounding; Thereby be unlikely to clobber when the driver is slowly gone under parking of side position or jam situation, offer help for driver safety goes.This device has numerous advantages such as cheap, easy to use.

Description of drawings

Fig. 1 is the hardware block diagram of the utility model;

Fig. 2 drives receiving circuit figure;

Fig. 3 is the filter shape amplification circuit diagram;

Fig. 4 is single main circuit figure;

Fig. 5 is the LCD MODULE circuit diagram;

Fig. 6 is a main program flow chart;

Below in conjunction with accompanying drawing the utility model is done further explain.

Embodiment

As shown in Figure 1; Present embodiment provides a kind of SCM Based automobile and visits apart from appearance; Comprise 4 ultrasonic sensor probes that are installed on the bumper of automobile front and back; 4 ultrasonic sensor probes are connected with the filtering amplification and rectification circuit through driving receiving circuit, and the filtering amplification and rectification circuit is connected with single-chip microcomputer, also is connected with LCD Liquid Crystal Module and hummer on the single-chip microcomputer.

Visiting apart from appearance before the automobile is to utilize the ultrasonic ranging principle, and the ultrasonic ranging principle generally adopts transit time method (time of flight), that is:

D1/2ct (1)

In the formula, D is a testing distance, and c is the aerial velocity of propagation of ultrasound wave, and t is that ultrasound wave is from being transmitted into the time interval that receives echo.

Utilize the Timer of single-chip microcomputer can accurately measure the value of t, c can be considered constant (getting c=331.4m/s usually), thereby just can calculate the distance of ultrasonic probe and barrier according to formula (1).

4 ultrasonic sensor probes (for emission receives integrated probe) are installed on automobile rear bumper; Let each probe a branch of ultrasonic pulse string of emission and judgement whether echo is arranged in turn by control circuit during reversing; Then computed range of echo is arranged, get that distance of lacking most and be used for showing and the sound caution with barrier.

Below provide concrete implementation process:

1, hardware circuit design

1.1 driving receiving circuit

With reference to Fig. 2, drive receiving circuit and form by 4 identical circuit, choose wherein the 1 tunnel as shown in Figure 2.The train of impulses (8 to 12) of the 40kHz that is at first produced by the single-chip microcomputer delivery outlet is delivered to SOUT1, again through all transformer T1 in the Darlington driving circuit drives of being made up of Q1 and Q2, makes the secondary ultrasonic probe generation ultrasound wave that connects of T1.The echoed signal that the while ultrasonic probe receives is amplified via the IF amplifier circuit that Q3, R6, R7, R8, R9, C1 form, and the signal RCV1 that exports is delivered to late-class circuit amplify.The enlargement factor of this grade is about 62 times.R4, C2 are used for power filter among the figure, and R5 is used for impedance matching.

1.2 amplification filtering shaping circuit

With reference to Fig. 3, because the ultrasonic echo signal that receives of receiving circuit is very faint, and can be mingled with various noises, all need filtering, amplification, shaping just can deliver to single-chip microcomputer later on to judge.Fig. 3 is the filtering amplification and rectification circuit.IC2A1 and IC2A2 are the low noise dual operational amplifiers by single power supply; They can use TL072 or RC4558, form the two-stage active band-pass filter with resistance capacitance, and its centre frequency is 40kHz; First order gain is 20, and second level gain is 120.C26, D21, D22, C28 form detecting circuit among the figure, and to search the positive half-wave in the echoed signal, the SIN signal of output is given analog comparator.

1.3 single-chip microcomputer

With reference to Fig. 4, present embodiment needs the STC89C52 single-chip microcomputer of STC Corporation.The STC89C52 single-chip microcomputer is a kind of low-power consumption, high-performance CMOS 8 8-digit microcontrollers, has 8K at system programmable Flash storer.On single-chip, have 8 dexterous bit CPUs and, make that STC89C52 is that numerous embedded Control application systems provide high flexible, ultra effective solution at system programmable Flash.STC89X52 can reduce to the operation of 0Hz static logic in addition, supports 2 kinds of softwares can select energy-saving mode.Under the idle pulley, CPU quits work, and allows RAM, timer/counter, serial ports, interruption to work on.Under the power down protection mode, the RAM content is preserved, and oscillator is freezed, and all work of single-chip microcomputer stop, till next one interruption or hardware reset.The highest operation frequency 35Mhz, 6T/12T is optional.

After detection, add analog comparator, adopt the LM111 chip here, an analog quantity of sending here and a standard value are compared.When being higher than this value; High (or low) level of output; Otherwise, then export low (or high) level, promptly utilize analog comparator to detect and whether receive echo; Utilize the cycle period of the accurate measurement of sound of timer two-way time and control emission and detection of echoes, utilize the pattern 0 (synchronous shift register mode) of UART to expand parallel delivery outlet.Single chip circuit is as shown in Figure 4.The P1.2-P1.5 mouth is used for producing the 40kHz train of impulses among the figure, and the P1.7 mouth is used to export caution sound.The 2nd pin INPUT (input end of analog comparator) of LM111M chip is used for detection of echoes, and the 3rd pin INPUT connects reference voltage (threshold values of echo), gets into single-chip microcomputer through the signal that produces behind the analog comparator through the P1.0 mouth.

1.4 liquid crystal display

LCD display spare has that working current is little, in light weight, low in energy consumption, the life-span is long, the clear advantage such as attractive in appearance of writing, in the instrument that portable apparatus, low-power consumption are used, has obtained widespread use.Along with the decline of LCD display price and the raising of performance, the trend that replaces the LED device with LCD is more and more obvious.

The LCD Liquid Crystal Module of present embodiment adopts 1602 type LCDs of Changsha sun people Electronics Co., Ltd., and this display is industrial character mode lcd, can show i.e. 32 characters (16 row, 2 row) of 16x02 simultaneously.

With reference to Fig. 5; Present embodiment adopts the dereference mode to utilize the I/O interface line of single-chip microcomputer to realize and the linking of dot character type LCD MODULE; Fig. 5 is a FPDP with the P0 mouth of 89C52, and the P3 mouth is realized and being connected of dot character type LCD MODULE as control port.Its time sequential routine is adopted software simulation fully; When write operation; The negative edge that is signal E is effective; On the software setting order; RS and

state are set earlier; Data are set again, produce the E signal pulse then, RS and

state at last reset.When read operation; Make the high level of signal E effective, so on the software setting order, RS and R/W state are set earlier; The E signal is set again for high; At this moment from the data port reading of data, then the E signal is put lowly, RS and

state at last reset.Potentiometer is V among Fig. 5 ₀End provides adjustable driving voltage, in order to realize showing the adjusting of contrast.

2, software design

With reference to Fig. 6, The software adopted C language, modular design.Software mainly is made up of master routine and functional module subroutine, to strengthen the readability of program, in debug process, earlier each functional module subroutine is debugged earlier one by one at last, after all subroutines are all passed through, carries out comprehensive debugging again.The process flow diagram of master routine is as shown in Figure 5, is mainly used in the completion initialization, and control port produces the 40kHz train of impulses, and the startup of control timer and stopping to detect calling of subroutines such as ultrasonic echo and calculating, demonstration, sound.

On the software design, made full use of two the 16 bit timing counter T0 and the T1 of STC89C52 single-chip microcomputer.T0 is set to timing mode, is used for the control emission and detects the round-robin cycle; T1 is used for measure calculating sound wave two-way time.

The measuring distance of this detection instrument is 0～1.5m, resolution 0.1m.In 1.1～1.5m scope is the place of safety, and it is that 0.5Hz " drips, drips " low-frequency sound that hummer sends frequency; In 0.6～1.0m scope is slow-drivezone, and hummer sends the intermediate frequency sound that frequency is 5Hz; In 0～0.5m scope is the explosive area, and hummer sends the sound that frequency is the 100Hz upper frequency, and hummer is mute beyond the 1.5m.After detection instrument calculates obstacle distance, on the LCD LCD screen, show distance apart from barrier.

Claims

1. a SCM Based automobile is visited apart from appearance; It is characterized in that; Comprise 4 ultrasonic sensor probes that are installed on the bumper of automobile front and back; 4 ultrasonic sensor probes are connected with the filtering amplification and rectification circuit through driving receiving circuit, and the filtering amplification and rectification circuit is connected with single-chip microcomputer, also is connected with LCD Liquid Crystal Module and hummer on the single-chip microcomputer.

2. SCM Based automobile as claimed in claim 1 is visited apart from appearance, it is characterized in that, described ultrasonic sensor probe receives the ultrasonic sensor probe of integrated probe for emission.

3. SCM Based automobile as claimed in claim 1 is visited apart from appearance, it is characterized in that described single-chip microcomputer is the STC89C52 single-chip microcomputer.

4. SCM Based automobile as claimed in claim 1 is visited apart from appearance, it is characterized in that described LCD Liquid Crystal Module is 1602 type LCDs.