accelerometer vehicle

8/13/2019 Accelerometer Vehicle

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Voltage regulator ( generating 5v dc)

Pinout of the 7805 regulator IC. Pinout of the 7812

regulator IC.

1. Unregulated voltage in 1. Unregulated voltage in

2. Ground 2. Ground

3. Regulated voltage out 3. Regulated voltage out

The power supply designed for catering a fixed demand connected in

this project.

.


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MICROCONTROLLER

BLOCK DIAGRAM


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The microcontroller used here is atmega 16 which has inbuilt adc and

counter along with microcontroller.the pin configuration and details

are given below.

The ATmega16 is a low-power CMOS 8-bit microcontrollerbased on the AVR enhanced RISC architecture. By executing

powerful instructions in a single clock cycle, the ATmega16 achieves

throughputs approaching 1 MIPS per MHz allowing the system

designer to optimize power consumption versus processing speed.

The AVR core combines a rich instruction set with 32 generalpurpose working registers.

All the 32 registers are directly connected to the ArithmeticLogic Unit (ALU), allowing two independent registers to be accessed

in one single instruction executed in one clock cycle. The resulting

architecture is more code efficient while achieving throughputs up to

ten times faster than conventional CISC microcontrollers.

PB0-PB7 PD0-PD7


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The ATmega16 provides the following features: 16K bytes ofIn-System Programmable Flash Program memory with Read-While-

Write capabilities, 512 bytes EEPROM, 1K byte SRAM, 32 generalpurpose I/O lines, 32 general purpose working registers, a JTAG

interface for Boundary-scan, On-chip Debugging support and

programming, three flexible Timer/Counters with compare modes,

Internal and External Interrupts, a serial programmable USART, a

byte oriented Two-wire Serial Interface, an 8-channel, 10-bit ADC

with optional differential input stage with programmable gain (TQFP

package only),a programmable Watchdog Timer with Internal

Oscillator, an SPI serial port, and six software selectable powersaving modes. The Idle mode stops the CPU while allowing the

USART, Two-wire interface, A/D Converter, SRAM,

Timer/Counters, SPI port, and interrupt system to continue

functioning. The Power-down mode saves the register contents but

freezes the Oscillator, disabling all other chip functions until the next

External Interrupt or Hardware Reset. In Power-save mode, the

Asynchronous Timer continues to run, allowing the user to maintain a

timer base while the rest of the device is sleeping.

The ADC Noise Reduction mode stops the CPU and all I/Omodules except Asynchronous Timer and ADC, to minimize

switching noise during ADC conversions. In Standby mode, the

crystal/resonator Oscillator is running while the rest of the device is

sleeping.

This allows very fast start-up combined with low-powerconsumption. In Extended Standby mode, both the main Oscillator

and the Asynchronous Timer continue to run.

The device is manufactured using Atmels high densitynonvolatile memory technology. The On-chip ISP Flash allows the


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program memory to be reprogrammed in-system through an SPI serial

interface, by a conventional nonvolatile memory programmer, or by

an On-chip Boot program running on the AVR core. The boot

program can use any interface to download the application program in

the Application Flash memory. Software in the Boot Flash sectionwill continue to run while the Application Flash section is updated,

providing true Read-While-Write operation. By combining an 8-bit

RISC CPU with In-System Self-Programmable Flash on a monolithic

chip, the Atmel ATmega16 is a powerful microcontroller that

provides a highly-flexible and cost-effective solution to many

embedded control applications.

The ATmega16 AVR is supported with a full suite of programand system development tools including: C compilers, macro

assemblers, program debugger/simulators, in-circuit emulators, and

evaluation kits.

Pin Descriptions


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VCC Digital supply voltage.

GND Ground.

Port A (PA7..PA0) Port A serves as the analog inputs to the A/D

Converter.


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Port A also serves as an 8-bit bi-directional I/O port, if the A/D

Converter is not used. Port pins can provide internal pull-up resistors

(selected for each bit). The Port A output buffers have symmetrical

drive characteristics with both high sink and source capability. When

pins PA0 to PA7 are used as inputs and are externally pulled low,they will source current if the internal pull-up resistors are activated.

The Port A pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

Port B (PB7..PB0) Port B is an 8-bit bi-directional I/O port with

internal pull-up resistors (selected for each bit). The Port B output

buffers have symmetrical drive characteristics with both high sink and

source capability. As inputs, Port B pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port Bpins are tri-stated when a reset

condition becomes active, even if the clock is not running.Port B also

serves the functions of various special features of the ATmega16 .

Port C (PC7..PC0) Port C is an 8-bit bi-directional I/O port with

internal pull-up resistors (selected for each bit). The Port C output

buffers have symmetrical drive characteristics with both high sink and

source capability. As inputs, Port C pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port C

pins are tri-stated when a reset

condition becomes active, even if the clock is not running. If the

JTAG interface is enabled, the pull-up resistors on pins PC5(TDI),

PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.

Port C also serves the functions of the JTAG interface andother special features of the ATmega16 as listed on page 61.

Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with

internal pull-up resistors (selected for each bit). The Port D outputbuffers have symmetrical drive characteristics with both high sink and

source capability. As inputs, Port D pins that are externally pulled low

will source current if the pull-up resistors are activated. The Port D

pins are tri-stated when a reset condition becomes active, even if the


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clock is not running. Port D also serves the functions of various

special features of the ATmega16.

RESET Reset Input. A low level on this pin for longer than the

minimum pulse length will generate a reset, even if the clock is not

running. The minimum pulse length is 0.1 vcc. Shorter pulses are notguaranteed to generate a reset.

XTAL1 Input to the inverting Oscillator amplifier and input to the

internal clock operating circuit.

XTAL2 Output from the inverting Oscillator amplifier.

AVCC AVCC is the supply voltage pin for Port A and the A/D

Converter. It should be externally

connected to VCC, even if the ADC is not used. If the ADC is used, it

should be connectedto VCC through a low-pass filter.

AREF AREF is the analog reference pin for the A/D Converter.

Adc

10-bit Resolution

0.5 LSB Integral Non-linearity

2 LSB Absolute Accuracy

13 - 260 s Conversion Time

Up to 15 kSPS at Maximum Resolution

8 Multiplexed Single Ended Input Channels

7 Differential Input Channels

2 Differential Input Channels with Optional Gain of 10x and

200x(1)

Optional Left adjustment for ADC Result Readout

0 - VCC ADC Input Voltage Range Selectable 2.56V ADC Reference Voltage

Free Running or Single Conversion Mode

ADC Start Conversion by Auto Triggering on Interrupt Sources

Interrupt on ADC Conversion Complete

Sleep Mode Noise Canceler


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bits in the ADMUX Register. The internal voltage reference may thus

be decoupled by an external capacitor at the AREF pin to improve

noise immunity.

The analog input channel and differential gain are selected by writing

to the MUX bits in ADMUX. Any of the ADC input pins, as well asGND and a fixed bandgap voltage reference, can be selected as single

ended inputs to the ADC. A selection of ADC input pins can be

selected as positive and negative inputs to the differential gain

amplifier.If differential channels are selected, the differential gain

stage amplifies the voltage difference

between the selected input channel pair by the selected gain factor.

This

amplified value then becomes the analog input to the ADC. If singleended channels are used, the gain amplifier is bypassed altogether.

The ADC is enabled by setting the ADC Enable bit, ADEN in

ADCSRA. Voltage reference and input channel selections will not go

into effect until ADEN is set. The ADC does not consume power

when ADEN is cleared, so it is recommended to switch off the ADC

before entering power saving sleep modes.

The ADC generates a 10-bit result which is presented in the ADC

Data Registers,ADCH and ADCL. By default, the result is presented

right adjusted, but can optionally be presented left adjusted by setting

the ADLAR bit in ADMUX.

If the result is left adjusted and no more than 8-bit precision is

required, it is sufficient to read ADCH. Otherwise, ADCL must be

read first, then ADCH, to ensure that the content of the Data Registers

belongs to the same conversion. Once ADCL is read, ADC access to

Data Registers is blocked. This means that if ADCL has been read,and a conversion completes before ADCH is read, neither register is

updated and the result from the conversion is lost. When ADCH is

read, ADC access to the ADCH and ADCL Registers is re-enabled.

The ADC has its own interrupt which can be triggered when a

conversion completes. When ADC access to the Data Registers is


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prohibited between reading of ADCH and ADCL, the interrupt will

trigger even if the result is lost.

Starting a Conversion

A single conversion is started by writing a logical one to the ADC

Start Conversion bit,ADSC. This bit stays high as long as the

conversion is in progress and will be cleared by hardware when the

conversion is completed. If a different data channel is selected while a

conversion is in progress, the ADC will finish the current conversion

before performing the channel change.

Alternatively, a conversion can be triggered automatically by varioussources. Auto Triggering is enabled by setting the ADC Auto Trigger

Enable bit, ADATE in ADCSRA. The trigger source is selected by

setting the ADC Trigger Select bits, ADTS in SFIOR When a positive

edge occurs on the selected trigger signal, the ADC prescaler is reset

and a conversion is started. This provides a method of starting

conversions at fixed intervals. If the trigger signal still is set when the

conversion completes, a new conversion will not be started. If another

positive edge occurs on the trigger signal during conversion, the edge

will be ignored. Note that an Interrupt Flag will be set even if the

specific interrupt is disabled or

the global interrupt enable bit in SREG is cleared. A conversion can

thus be triggered without causing an interrupt. However, the Interrupt

Flag must be cleared in order to trigger a new conversion at the next

interrupt event


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Body in motion usually experience vibration as well as shock. When a mobile falls on a floor, it is

subjected to shock. When a vehicle moves on a bumpy road, it experiences vibrations. Likewise, there

are many situations, where an object encounters shock and vibrations. Sometimes, they survive and at

times, they get damaged. When delicate items like glass, crockery, etc. are packaged properly, they can

withstand severe shock and vibrations. Whether a system will survive or not, how do we know this a

priori? While some vibrations are desirable, some may be disturbing or even destructive. Hence, often a

need is felt to understand the causes of vibrations and to develop methods to measure and prevent them.

An ability of a system to withstand vibrations and shock depends upon the g level the system can

withstand. To measure these glevels, a sensor accelerometer is used.

An accelerometeris a sensor that measures the physical acceleration experienced by an object due to

inertial forces or due to mechanical excitation. Acceleration is defined as rate of change of velocity withrespect to time. It is a measure of how fast speed changes. It is a vector quantity having both magnitude

and direction. As a speedometer is a meter to measures speed, an accelerometer is a meter to measure

acceleration. An ability of an accelerometer to sense acceleration can be put to use to measure a variety

of things like tilt, vibration, rotation, collision, gravity, etc. Accelerometers measure in terms of g (g is

acceleration measurement for gravity which is equal to 9.81m/s). Accelerometers are made using tilt

sensors.

THEORY OF ACCELEROMETERS - WHAT IS AN ACCELEROMETER?The term Accelerometersrefer to the transducers which comprises of mechanical sensing element and

a mechanism which converts the mechanical motion into an electrical output.Theory behind working of accelerometers can be understood from the mechanical model of

accelerometer, using Newtonian mechanics. The sensing element essentially is a proof mass (also

known as seismic mass). The proof mass is attached to spring which in turn is connected to its casing.

In addition, a dashpot is also included in a system to provide desirable damping effect; otherwise system

may oscillate at its natural frequency. The dashpot is attached (in parallel or in series) between the mass

and the casing. The unit is rigidly mounted on the body whose acceleration is of interest.


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When the system is subjected to linear acceleration, a force (= mass * acceleration) acts on the proof-

mass. This causes it to deflect; the deflection is sensed by a suitable means and is converted into an

equivalent electrical signal.

When force is applied on the body, proof mass moves. Its movement is countered by spring and damper.


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Therefore, if m = proof mass of the bodyx = relative movement of the proof-mass with respect to the framec = damping coefficientk = spring stiffness

then


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Thus, with the knowledge of damping coefficient(c ), spring stiffness (k), and proof mass (m), for a useful

acceleration sensor, it is sufficient to provide a component that can move relative to sensors housing and

a means to sense the movement.

Displacement and acceleration are related by fundamental scaling law. A higher resonant frequency

implies less displacement or low sensitivity.

TYPES OF ACCELEROMETERSAs movement of the proof mass is sufficient for an accelerometer, accelerometers are designed using

various sensing principles.

PotentiometricOne of the simplest accelerometer type - it measures motion of the proof mass motion by attaching the

spring mass to the wiper arm of a potentiometer. Thus position of the mass and thereby, changing

acceleration is translated to changing resistance.


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The natural frequency of these devices is generally less than 30 Hz, limiting their application to low

frequency vibration measurements. Dynamic range is also limited. But they can measure down to 0 Hz

(DC response).

Capacitive accelerometersCapacitive accelerometers sense a change in electrical capacitance, with respect to acceleration. Single

capacitor or differential capacitors can be used; differential ones being more common


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When force (generated due to acceleration) is applied, piezoelectric material deforms to generate the

charge. This charge is proportional to the applied force or in other words, proportional to acceleration (as

mass is constant). The charge is converted to voltage using charge amplifiers and associated signal

conditioning circuit.

Compared to other type of accelerometers, piezoelectric accelerometers offer unique advantages Wide dynamic rangeExcellent linearityWide frequency rangeNo wear and tear due to absence of moving parts No external power requirement

However, alternating acceleration only can be measured with piezoelectric accelerometers. Theseaccelerometers are not capable of measuring DC response.

Piezo-resistive accelerometers


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Piezo-resistive accelerometers use piezo-resistive materials, i.e., strain gauges. On application of the

force (due to acceleration), resistance of these strain gages changes. The change in resistance is

monitored to measure the acceleration.

Piezo-resistive elements are typically used in micro-machined structures. They have true DC response.

They can be designed to measure upto 1000 g.

Variable inductance accelerometersUsing the concept very similar to the one used in LVDTs, variable inductance accelerometers can be

designed. In these accelerometers, proof mass is made of ferromagnetic materials. The proof mass is

designed in the form of core which can move in or out of the coil.


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Magnetoresistive accelerometers

Magnetoresistive accelerometers employ magnetoresistive effect. Resistance of magnetic materials

changes when exposed to varying magnetic field. These accelerometers are similar to Hall Effect

accelerometers; the only difference is the use of magnetoresistive material instead of Hall element.

Hence, the change in resistance due to the applied acceleration is measured.

FBG Based accelerometersAfiber Bragg grating (FBG)is a type of distributed Bragg reflector fabricated in a short section of optical

fiber that reflects specific wavelengths of light and transmits all others. When a broad-spectrum light is

transmitted through the fiber, and the transmitted beam impinges on the grating, a part of the signal is

transmitted through, and another part is reflected off. The reflected signal is centered at Bragg
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wavelengths. Any change in the grating pitch of the fiber caused by strain or temperature results in a shift

of Bragg wavelength. This is the property used for sensing of movement of mass in the accelerometers.

In FBG sensor based accelerometers, the acceleration is coupled to a mechanical load on the FBG. Due

to the strain experienced by the FBGs (as a result of applied acceleration), there is a shift in the reflected

Bragg wavelengths. Shift in the wavelengths is then calibrated to the level of acceleration.

Heated Gas accelerometersHeat Gas accelerometers measure internal changes in heat transfer due to acceleration. These

accelerometers use gas as a proof mass.Gas is enclosed in a cavity and a heat source is suspended at the center. Two (or more) thermistors areplaced at equal distances from the suspended heat source.Under rest condition (or zero acceleration), the gas is heated to an equilibrium temperature, the heat

gradient is symmetrical, and hence two thermistors are at same temperature.


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Under acceleration, the heat gradient become asymmetrical due to convective heat transfer, the gas

shifts to the direction opposite the motion (the gas is the inertial mass) causing a temperature gradient.

The temperature gradient is calibrated in terms of acceleration.

MEMS-Based AccelerometersMEMS is an enabling technology which allows miniaturization of existing devices, to offer solutions which

cannot be attained by macro-machined products. MEMS allows the complex electromechanical systems

to be manufactured using batch fabrication techniques, decreasing the cost and increasing the reliability.

It allows integrated systems, viz., sensors, actuators, circuits, etc. in a single package and offers

advantages of reliability, performance, cost, ease of use, etc. This technology is being utilized widely to

manufacture state of the art MEMS-Based Accelerometers.

First MEMS accelerometers used piezoresistors. However, piezoresistors are less sensitive than

capacitive detection. Most of the MEMS accelerometer use capacitive sensing principle. Typical MEMS

accelerometer is composed of movable proof mass with plates that is attached through a mechanical

suspension system to a reference frame. Movable plates (part of the proof mass) and ?xed outer plates

form differential capacitor. Due to application of the force, proof mass deflects; the deflection is measured

in terms of capacitance change.


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SEM photograph of MEMS 3D accelerometer is shown below


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METHODS OF CALIBRATIONCalibration of an accelerometer is to accurately determine its sensitivity at various frequencies of interest.

Methods commonly employed to calibrate the accelerometers are:

1. Gravity TestThe accelerometers having true DC response can be calibrated using this method.In this method, an accelerometer is placed with its sensitive axis (+ and -) along the direction of gravity

and the outputs are noted. Difference between the two readings corresponds to 2 g difference. From this

scale factor can be computed.

2. Back-to-back Accelerometer CalibrationThis technique is arguably the most convenient method for accelerometer calibration.Back-to-back calibration involves coupling the test accelerometer directly to a (NIST) traceable double-

ended calibration standard accelerometer and driving the coupled pair with a vibration exciter at various

frequencies and acceleration (g) levels. Since the accelerometers are tightly coupled together, both


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experience exactly the same motion, thus the calibration of the back-to-back standard accelerometer can

be precisely transferredto the test accelerometer.

APPLICATIONS OF ACCELEROMETERSAccelerometers are one of those sensors which find numerous applications in academia as well as in

large number of industries. These applications range from airbag sensor in automotive applications to

monitoring vibrations on a bridge and in many military and space systems. There are a number

of practical applications for accelerometers; accelerometers are used to measure static acceleration

(gravity), tilt of an object, dynamic acceleration, shock to an object, velocity, and the vibration of an object.

Accelerometers are being used nowadays in mobile phones, laptops, washing machines, etc.

Motor

In any electric motor, operation is based on simple electromagnetism. Acurrent-carrying

conductor generates a magnetic field; when this is then placed in an external magnetic field, itwill experience a force proportional to thecurrent in the conductor, and to the strength of the

external magnetic field. As you are well aware of from playing with magnets as a kid, opposite

(North and South) polarities attract, while like polarities (North and North, South and South)

repel. The internal configuration of aDC motor is designed to harness the magnetic interaction

between acurrent-carrying conductor and an external magnetic field to generate rotationalmotion.

Let's start by looking at a simple 2-poleDC electric motor (here red represents a magnet or

winding with a "North" polarization, while green represents a magnet or winding with a "South"

polarization).

EveryDC motor has six basic parts -- axle, rotor (a.k.a., armature), stator, commutator, fieldmagnet(s), and brushes. In most common DC motors (and all thatBEAMers will see), the
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external magnetic field is produced by high-strength permanent magnets1. The stator is the

stationary part of the motor -- this includes the motor casing, as well as two or more permanent

magnet pole pieces. The rotor (together with the axle and attached commutator) rotate withrespect to the stator. The rotor consists of windings (generally on a core), the windings being

electrically connected to the commutator. The above diagram shows a common motor layout --

with the rotor inside the stator (field) magnets.

The geometry of the brushes, commutator contacts, and rotor

windings are such that when power is applied, the polarities ofthe energized winding and the stator magnet(s) are misaligned,

and the rotor will rotate until it is almost aligned with the stator's

field magnets. As the rotor reaches alignment, the brushes moveto the next commutator contacts, and energize the next winding.

Given our example two-pole motor, the rotation reverses the

direction ofcurrent through the rotor winding, leading to a "flip"

of the rotor's magnetic field, driving it to continue rotating.

In real life, though,DC motors will always have more than two

poles (three is a very common number). In particular, this avoids"dead spots" in the commutator. You can imagine how with our

example two-pole motor, if the rotor is exactly at the middle of

its rotation (perfectly aligned with the field magnets), it will get"stuck" there. Meanwhile, with a two-pole motor, there is a

moment where the commutator shorts out the power supply (i.e.,

both brushes touch both commutator contacts simultaneously).

This would be bad for the power supply, waste energy, anddamage motor components as well. Yet another disadvantage of

such a simple motor is that it would exhibit a high amount oftorque "ripple" (the amount oftorque it could produce is cyclicwith the position of the rotor).

So since most smallDC motors are of a three-pole design, let's tinker with the workings of onevia an interactive animation (JavaScript required):

You'll notice a few things from this -- namely, one pole is fully energized at a time (but twoothers are "partially" energized). As each brush transitions from one commutator contact to the
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next, one coil's field will rapidly collapse, as the next coil's field will rapidly charge up (this

occurs within a few microsecond). We'll see more about the effects of this later, but in the

meantime you can see that this is a direct result of the coil windings' series wiring:

There's probably no better way to see how an averageDC motor is

put together, than by just opening one up. Unfortunately this is

tedious work, as well as requiring the destruction of a perfectly

good motor.

Luckily for you, I've gone ahead and done this in your stead. Theguts of a disassembled Mabuchi FF-030-PN motor (thesame

model thatSolarbotics sells) are available for you to seehere (on

10 lines / cm graph paper). This is a basic 3-poleDC motor, with 2

brushes and three commutator contacts.

The use of an iron core armature (as in the Mabuchi, above) is quite common, and has a numberof advantages

2. First off, the iron core provides a strong, rigid support for the windings -- a

particularly important consideration for high-torque motors. The core also conducts heat away

from the rotor windings, allowing the motor to be driven harder than might otherwise be thecase. Iron core construction is also relatively inexpensive compared with other construction

types.

But iron core construction also has several disadvantages. The iron armature has a relatively high

inertia which limits motor acceleration. This construction also results in high winding

inductanceswhich limit brush and commutator life.

In small motors, an alternative design is often used which features a 'coreless' armature winding.

This design depends upon the coil wire itself for structural integrity. As a result, the armature is

hollow, and the permanent magnet can be mounted inside the rotor coil. CorelessDC motorshave much lower armatureinductance than iron-core motors of comparable size, extending brush

and commutator life.
http://encyclobeamia.solarbotics.net/articles/dc.htmlhttp://www.solarbotics.com/order/default.asp?ACTION=CAT&CATID=8#tar42http://www.solarbotics.com/order/default.asp?ACTION=CAT&CATID=8#tar42http://www.solarbotics.com/http://www.solarbotics.net/starting/200111_dcmotor/pix/mabuchi_exploded.jpghttp://encyclobeamia.solarbotics.net/articles/dc.htmlhttp://encyclobeamia.solarbotics.net/articles/torque.htmlhttp://encyclobeamia.solarbotics.net/articles/inductance.htmlhttp://encyclobeamia.solarbotics.net/articles/dc.htmlhttp://encyclobeamia.solarbotics.net/articles/inductance.htmlhttp://encyclobeamia.solarbotics.net/articles/inductance.htmlhttp://encyclobeamia.solarbotics.net/articles/dc.htmlhttp://encyclobeamia.solarbotics.net/articles/inductance.htmlhttp://encyclobeamia.solarbotics.net/articles/torque.htmlhttp://encyclobeamia.solarbotics.net/articles/dc.htmlhttp://www.solarbotics.net/starting/200111_dcmotor/pix/mabuchi_exploded.jpghttp://www.solarbotics.com/http://www.solarbotics.com/order/default.asp?ACTION=CAT&CATID=8#tar42http://www.solarbotics.com/order/default.asp?ACTION=CAT&CATID=8#tar42http://encyclobeamia.solarbotics.net/articles/dc.html


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MOTOR DRIVERL 93D

The most commonly used H-bridges are L293D and L298. L293

have maximum current rating of 600mA while that of L298 is 2A.L293B and L293D are available in market. If we use L293B wehave to put 4 protection diodes while in L293D, diodes are insidethe IC. L298 requires external protection diodes.

L293D has two channels. i.e, we can connect two motors to thesame bridge. I have driven 4 motors of 250mA using L293D, with2 motor in each channel.


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Ratings of L293DOutput Current 1 A Per Channel (600 mA for L293D)Peak Output Current 2 A Per Channel (1.2 A for L293D)

Maximum VC4.5 to 36V (>VSS)( it should be greaterthan or equal the supply voltage,vss) input side(input toL293D from parallel port or microcontroller) VIH High-levelinput voltage( a voltage which L293D takes input as HIGH(1))

VC 7 V (2.3 to VC)VC 7 V (2.3 to 7 V)VIL High-level input voltage( a voltage which L293D takesinput as LOW(0)) (-.3 to 1.5V), remember that VIL should not

be less than -.3V output side(output of L293D to motor)VOH High-level output voltage (VCC2 1.8, VCC2 1.4)VOL Low-level output voltage (1.2v , 1.8v). If you want to usePWM to control L293D then apply PWM output to the chipinhibit of the IC.

Remember all these parameters when we connect L293D incircuits. L293B are available, if you use it use 4 externalprotection diodes. L293D costs around Rs.90 L293D in circuit sothat it won't create any problems.

TROUBLESHOOTING L293D:

1. Insert IC into the breadboard. Make sure that IC is insertedproperly into breadboard. You can verify it using continuity test in


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the multimeter. Test continuity between the pins of the IC and theholes of the breadboard. If you get a beep then you can sure thatIC isfitted strongly into breadboard and the portion ofbreadboard you are using is good.

2. Test the continuity in the 16 pins of the IC and the breadboardholes, to make sure that nothing goes wrong. You should bethorough with the steps you are taking.

3. Apply Vss=5V(Pin 16) . The first thing to apply when youconnect an IC is applying Vcc and ground. Remember Vss shouldbe in the range of 4.5V to 7V.

4. Now connect ground at Pins 4, 5,12,13. Remember if you usemultiple supplies, you should short circuit all grounds and thisground is applied to the Pins.

5. Now Vss and Gnd applying is over.

6. Now apply +5V to chip enable pins . Chip enable pins arepin1,9.

7. Here we are trying to use both channels, atleast test bothchannels of the IC so that we can test whether IC is good or not.

8. Apply Vc at Pin8. For testing the IC you can apply Vc=Vss=5V.When you connect the motor you should apply Vc>Vss or may itcanbe equal also. I have tested it.

9. The following test are done for each channels separatively. Inthe following explanation I refer '1' as +5V(Vss) and '0' as ground.

10.Apply Input 1 = Input 2 =0( ie,ground ) and connect multimeterto output 1 and ground of the circuit. Now test output1 andoutput2 voltages. Both should be zero at this condition.


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11.Apply Input1=1 and Input2=0 and check voltages at output1and output2. Remember your multimeter's one lead should beground. Then you should get one output= Vc and other output =

0. Suppose if you got output1=Vc and output2=0.

12.Apply Input1=0 and Input2=1 and check voltages at output1and output2. Then output1=0 and output2=Vc. That is this case isshould be reverse of the previous case, motor will rotate inopposite direction.

13.Apply Input1=1 and Input2=1 and check voltages at output1

and output2. Then output1=output2=Vc. This is the braking case.

14.Test conditions 10-13 for both channels to test the IC is good.You should test it thoroughly so that a repetition is not needed. Ifyour IC is not working, repeat steps 1-13 to make sure IC is bad.

15.The most problems occurring are breadboard problems,IC notinserted properly, applying Vss and Vc wrongly(this cansometimes cause problems to IC), not disabling chip inhibit,absence of common ground.

16. If you are applying Vc=Vss = +5V, then you can use twoLED's to see outputs.

17.When chip inhibit is enabled, ie chip is not working the outputswill be high impedance, you can test high impedance using anLED. First connect the cathode of LED to ground through a series

resistor of 330ohm and test the output. LED will not glow. Theapply 5V to the anode of the LED and apply output to the cathodethrough a series resistor of 330 ohm. Now also LED won't glow.Now you can assure that the output is high impedance.


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18.Before connecting motor to the outputs of L293D, first test themotor is working with the desired VC by applying VC and grounddirectly to the two leads of the motor. Confirm this first, thenconnect the motor.

Train auto collision avoider

The same ir transmitter and receiveris used to detect theobstacles in front of the train and is used asa separate model forauto collision avoider.

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accelerometer vehicle

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