cảm biến siêu âm sensor RF05

sensor sr05 cảm biến siêu âm, tài liệu sử dujnh tiếng việt giúp các bạn nào cần làm báo cáo tiếng anh, trong tài liệu trình bày rõ ràng cấu tạo, tác dụng và cách giao tiếp giữa vi điều khiển với cảm biến siêu âm rf05

2014

Application of Distance Sensor

in Parking Car

Phạm Duy Khanh Đinh Tiến Đạt

Lê Thanh Tùng CTT Cơ Điện Tử K55

Table of Contents

A Abstract 2

B Introduction and Overview 3

C Approach 4

I Structure of our system 4

II Hardware 4

1 Distance sensor 4

2 Microcontroller 10

3 Display device 11

4 Actuator and Status devices 12

III Software 13

1 Programer and complier software 13

2 Simulation platform 15

3 PCB design platform 15

D Design System 16

I Hardware 16

1 Power Supply Block (LM7805) 16

2 Main Block 17

3 Actuator Block 20

II Software 22

1 Distance sensor (HC SR04) code 23

2 Display device (LCD 16x2) code 26

3 Actuator (DC motor) code 29

E Results of our system 32

F Conclusion 32

List of fingures

Figure 1: Structure of System 4

Figure 2: Operation of Optical Sensor 5

Figure 3: Sharp GP2Y0A02YK0F analog distance sensor 20-150 cm 5

Figure 4: Operation of Ultrasonic Sensor 6

Figure 5: HC SR04 Ultrasonic sensor 7

Figure 6: Operation of Microwave Sensor 8

Figure 7: HB-100 Microwave Sensor 8

Figure 8: Some types of lcd panel 11

Figure 9: LCD text 16x2 12

Figure 10: DC Motor 13

Figure 11: AVR Studio 6 14

Figure 12: User Interface of AVR Studio 6 14

Figure 13: Proteus 7.8 15

Figure 14: User Interface of Proteus 7.8 15

Figure 15: Altium Designer 14 15

Figure 16: PCB Design of Product 16

Figure 17: IC LM7805 16

Figure 18: Schematic of Power Block 17

Figure 19: Block Diagram of Main Block 17

Figure 20: Schematic of Main Block 18

Figure 21: Real Product 19

Figure 22: IC LM298 20

Figure 23: Schematic of L298 Module 21

Figure 24: Real of L298 Module 21

Figure 25: Flow Chart of Main Program 22

Figure 26: Timing Diagram of HC SR04 23

Figure 27: Flow Chart of Get Width Pulse on HC SR04 24

Figure 28: Flow Chart of LCD in 4bit mode 26

Figure 29: PWM Waveform 30

Figure 30: A Simlifed H Bridge 30

Figure 31: Timing Diagram of fast PWM on Timer 2 in Atmega8 31

A Abstract

An increasing number of new vehicles are being equipped with ultrasonic sensors These sensors detect the presence and proximity of objects in the pathway of the reversing vehicle and warn the driver through an audible signal This report

investigates the performance capabilities and potential safety effectiveness of these

systems in reducing the risks to small children and other pedestrians from

reversing vehicles These sensor systems are primarily designed and marketed as parking aids However, some are being promoted as safety systems with the

potential to reduce or prevent collisions with pedestrians, especially small children

In terms of detection area performance, parking aid systems sacrificed detection distance and height in order to suppress false or nuisance alarms The durability and reaction time results revealed there were no substantial performance

differences between the systems The safety benefits of these devices were then estimated based on these test results

B Introduction and Overview

There are many pedestrians struck and injured by reversing vehicles each year in Viet Nam However, this is likely an underestimate as this figure only represents those pedestrians struck in traffic situations It does not account for pedestrians injured or killed in private driveways or parking lots for example Therefore, the exact number of pedestrians injured or killed in Viet Nam is not known but studies

in other jurisdictions have highlighed this problem The study also found that most

of these non-traffic collisions involved toddlers Among the recommendations was

to investigate the potential of rear proximity sensors in detecting the presence of nearby children This paper reports on the performance of ultrasonic sensor systems The purpose was not to set out performance criterea but rather to investigate the capabilities of commercially available systems and to asses their potential effectiveness in reducing pedestrian collisions

C Approach of Product

I Structure of System

In our system, we have monitor to display infomation of status and distances recieved from distances sensor If the car is in dangerours regions, the red light is turned on and the buzzer is notified and speed of motor also reduced to zero to the car not cross to object

Figure 1: Structure of System

II Hardware

1 Distance sensor

a Introduce types of distance sensor

Measuring the level, position, distance and displacement of physical objects is

essential for many applications: process feedback control, performance evaluation, transport, traffic control, robotics, security systems, to name just a few

In our problem, we need a sensor that can mearsure extractly distances from source (car) to unknown body (unknown about shape, material, movement,etc)

Hence, we will consider 3 types of distance sensors: optical sensor, microwave sensor and ultrasonic sensor

 Optical Distance Sensor:

A light wave is transmitted by the sensor, reflected by the measuring object and

received by the detector The simplest way to calculate distances with optical sensors

is based on the determination of the elapsed time interval between emission and

reception of a pulse (signal burst) or series of pulses

Figure 2: Operation of Optical Sensor

 Ultrasonnic Distance Sensor:

Ultrasonic waves are mechanical oscillations at a frequency which is beyond the

audibility of humans (more than 20 kHz) By a mutual interference of ultrasonic

waves from the individual sensors, the high density of emitted energy in a certain direction can be reached Using the proper phasing of the transducers configured in a matrix, the concentration of energy in a small area is feasible The same phasing

principle can be implemented on the matrix of receivers for a reflected wave By the computer control of phases of transducers operating in a transmitting or receiving mode

 Travel time principle

The pulses containing a definite number of periodic waves propagate with sound

1 http://www.pololu.com/product/1137

velocity towards a measured object The pulses are then reflected from the measured object and picked up by the receiver (Figure 7.29) with a lag time equal to the

elapsed time between the emission and reception of pulses The received pulses of ultrasonic waves are transformed to the electrical signal by means of the

piezoelectric effect the scanning regime of operation is feasible (e.g in ultrasonic tomography)

 Doppler effect

The Doppler effect, (discovered by C Doppler in 1843) is the change in

frequency undergone by radiation (be it mechanical or electromagnetic) when it is reflected by an object that is moving with respect to the radiation transmitter If the reflector moves with velocity v the shift of frequency is approximately given by

Resolution: mm

Examples:

Figure 5: HC SR04 Ultrasonic sensor

US $3.61 2

 Microwave Distance Sensor (radar)

Microwaves are electromagnetic waves with high frequency (GHz range)

The procedures used in microwave sensors for distance and position measurement are analogical to those of ultrasonic sensors

The measurements are based on:

– The travel time measurement

– Doppler effect

– Frequency Modulated Continuous Wave (FMCW):

The FMCW-based sensor continuously sends signals with a periodical frequency modulated carrier wave The frequency difference is proportional to the distance

which can be calculated from the following equation:

Where fm is the frequency of the triangular modulating signal and fh s the frequency sweep

The precision of a FMCW radar system depends mainly on the linearity of the

triangular waveform of the frequency modulating signal

2 http://www.robotshop.com/en/hc-sr04-ultrasonic-range-finder.html

Travel time measurement is the original procedure used in radar systems for a

In Vietnam, we cannot buy HB100 or Sharp GP2Y0A02YK0F, so we

decide choose HC SR04 Ultrasonic Sensor to use in our problem

b Introduce features and characteristics of HC SR04

Ultrasonic ranging module HC-SR04 provides 2cm - 400cm non-contact measurement function, the ranging accuracy can reach to 3mm The modules includes ultrasonic transmitters，receiver and control circuit

The basic principle of work

 Using IO trigger for at least 10us high level signal

 The Module automatically sends eight 40 kHz and detect whether there is a pulse signal back

 If the signal back, through high level,time of high output IO duration is the time from sending ultrasonic to returning Test distance=(high level

timexvelocity of sound (340M/S) /2

Wire connecting direct as following:

1 5V Supply

2 Trigger Pulse Input

3 Echo Pulse Output

4 GND

If you are sourcing a ultrasonic ranging module , the HC-SR04 is good choose Its stable performance and high ranging accuracy make it a popular module in electronic market

Compared to the Shape IR ranging module , HC-SR04 is more inexpensive than it But it has the same ranging accuracy and longer ranging distance

More details:

 Power supply :5V DC

 Quiescent current : 2mA

 Effectual angle: 15 degree

 Ranging distance : 2cm - 500 cm

 Resolution : 0.3 cm

There are 4 pins out of the module : VCC , Trig, Echo, GND So it's a very easy

interface for controller to use it ranging The all process is : pull the Trig pin to high level for more than 10us impulse , the module start ranging ; finish ranging , If you find an object in front , Echo pin will be high level , and based on the different

distance, it will take the different duration of high level So we can calculated the distance easily :

Distance = ((Duration of high level)(Sonic :340m/s))/2 Finally,look at the back of the module All of the chip in the module have been

burnish, maybe the author want to prevent the designed from plagiarism But

ultrasonic ranging module is nearly the same principle,so it's not hard to speculated that the role of the chip - I'm sure at least one 74series chip on it) It is not a difficult task to crack it, but it's at so low a price, even cheaper than your copy

2 Microcontroller

a Overview of microcontroller

A microcontroller (sometimes abbreviated µC, uC or MCU) is a small computer on a single integrated circuit containing a processor core, memory, and

programmable input/output peripherals Program memory in the form of NOR

flash or OTP ROM is also often included on chip, as well as a typically small amount

of RAM Microcontrollers are designed for embedded applications, in contrast to themicroprocessors used in personal computers or other general purpose applications Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems By

reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems

b Why choose Atmega8?

With ease-of-use, low power consumption, and high level of integration in mind, microprocessors to deliver a unique combination of performance, power efficiency and design flexibility Optimized to speed time-to-market, they are based on the

industry's most code-efficient architecture for C and assembly programming

No other atmega 8 deliver more computing performance with better power efficiency Industry-leading development tools and design support let you get to market faster

Once there, the large AVR family lets you reuse your knowledge when improving your products and expanding to new markets—easily and cost-effectively

c Introducce features and characteristics of Atmega8

The low-power Atmel 8-bit AVR RISC-based microcontroller combines 8KB of

programmable flash memory, 1KB of SRAM, 512K EEPROM, and a 6 or 8 channel 10-bit A/D converter The device supports throughput of 16 MIPS at 16 MHz and operates between 2.7-5.5 volts

3 Display device

A liquid-crystal display (LCD) is a flat panel display, electronic visual display, or video

display that uses the light modulating properties of liquid crystals Liquid crystals do not emit light directly

LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images which can be displayed or hidden, such as preset words, digits, and 7-segment displays as in a digital clock They use the same basic technology, except that arbitrary

images are made up of a large number of small pixels, while other displays have larger

elements

LCDs are used in a wide range of applications including computer monitors, televisions, instrument panels, aircraft cockpit displays, and signage They are common in consumer devices such as video players, gaming devices, clocks, watches, calculators, and telephones,

Figure 8: Some types of lcd panel

Why choose LCD 16x2?

1.Easy to control

2.Enough space to display the information that user need to know about

module : distance , warning level

3.Friendly to users

Introduce features and characteristic of LCD 16x2

Figure 9: LCD text 16x2

FEATURES

• 5 x 8 dots with cursor

• Built-in controller (KS 0066 or Equivalent)

• + 5V power supply (Also available for + 3V)

• 1/16 duty cycle

• B/L to be driven by pin 1, pin 2 or pin 15, pin 16 or A.K (LED)

• N.V optional for + 3V power supply

4 Actuator and Status devices

In Fact , the systems contains the motion part and notification part There is car’s engine and notion light, speaker To simulate the real systems , we use a motor is such as car’s engine 3 leds and a chip speaker is used to be warning system

Why choose DC motor to simulate?

Figure 10: DC Motor

In this project , we only use motor to simulate the motion of car We need a motor

that easy to control, cheap So DC motor is best solution

DC (Direct Current) Motors are two wire (power & ground), continuous rotation motors When you supply power, a DC motor will start spinning until that power is removed Most

DC motors run at a high RPM (revolutions per minute), examples being computer cooling fans, or radio controlled car wheels!

III Software

1 Programer and complier software

We use AVR Studio v6.2 to write code and complier programs

Figure 11: AVR Studio 6

Atmel® Studio 6 is the integrated development platform (IDP) for developing and debugging Atmel ARM® Cortex®-M and Atmel AVR® microcontroller (MCU) based applications The Atmel Studio 6 IDP gives you a seamless and easy-to-use environment to write, build and debug your applications written in C/C++ or assembly code

Atmel Studio 6 is free of charge and is integrated with the Atmel Software Framework (ASF)—a large library of free source code with 1,600 ARM and AVR project

examples ASF strengthens the IDP by providing, in the same environment, access to ready-to-use code that minimizes much of the low-level design required for projects Use the IDP for our wide variety of AVR and ARM Cortex-M processor-based

MCUs, including our broadened portfolio of Atmel SAM3 ARM Cortex-M3 and M4 Flash devices

Figure 12: User Interface of AVR Studio 6

2 Simulation platform

Figure 13: Proteus 7.8

We use Proteus 7.8 software to dimulate our product before make real product

Figure 14: User Interface of Proteus 7.8

3 PCB design platform

Figure 15: Altium Designer 14

Altium Designer combines Schematic, ECAD Libraries, Rules & Constraints, BoM, Supply Chain Management, ECO Processes and World-Class PCB Design tools in one easy to use, Native 3D enhanced, Unified Environment, increasing