28-10-2016, 02:14 PM
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PROJECT DESCRIPTION
In this Project we use ATMEL-89S52 microcontroller and interfaced with the Ultrasonic Sensor Module for Detecting the Distance of any object from it .this sensor have transmit the sound waves and when sound waves is reflected by any object then calculate the time when wave is back to it and then according to distance formula we have find the distance of object from the sensor.
when any object is come near to this sensor then it will give the Interrupt to microcontroller and microcontroller display this distance to LCD that is used in our project. This complete project work in 5V Dc Power Supply.
COMPONENTS USED
• Lm 7805(Regulator)
• LEDs
• 2 Ceramic capacitors – 33pf
• 2 Electrolytic capacitors – 10uf / 25v and 1000uf/25V
• Four diodes
• 12v transformer
• Microcontroller ATMEL-89S52
• Resistor- 10K
• Crystal Oscillator
• Variable resistor – 10K
• Reset Switch
• Ultrasonic Sensor Module HC - SR04
• PCB
RESISTANCE
Resistance refers to the property of a substance that impedes the flow of electric current. Some substances resist current flow more than other. If a substance offers very high resistance to current flow it is called an insulator. If its resistance to current flow is very low, it is called a conductor. Resistivity refers to the ability of substance to resist current flow. Good conductors have low resistivity and insulators have high resistivity.
Ohm’s Law
George Simon Ohm (1789-1854), a German physicist, formulated the relationships among voltage, current, and resistance into what is referred to as Ohm’s law:
The current in a circuit is directly proportional to the applied potential difference and inversely proportional to the resistance of the circuit.
The International Standard (SI) unit of resistance is the ohm, designated by the Greek letter one ohm of resistance is equal to the resistance of a circuit in which a potential difference of one volt produces a current of one ampere.
Mathematically Ohm’s law is written as:
I = E/R
Where I is the current in amperes, E is the applied voltage (difference in potential) in volts and R is the resistance in ohms.
Therefore, voltage can be calculated using formula:
E = I * R
Resistance can be calculated using the formula:
R = E/I
It is important to note that adjusting voltage or current can not change resistance. Resistance in a circuit is a physical constant and can only be modified by changing components, exchanging resistance for those rated at more or fewer ohms, or by adjusting variable resistors.
Types of Resistors
Resistors come in variety of values and types. The most common type is fixed resistor. Fixed resistor have single value of resistance, which remain constant. There are also variable resistors that can be adjusted to vary or change the amount of resistance n a circuit.
The value of resistance of resistors is given in ohms. Resistors can have values from less than one ohm up to many millions of ohms.
1. Fixed Resistors
The most common fixed resistor is the composition type. The resistance element is made of graphite, or some other form of carbon, and alloy materials. These resistor generally have resistance values that range from 0.1Ω to 22 MΩ.
Another kind of fixed resistor is the wire wound type. The resistance element is usually made of nickel-chromium wire wound on a ceramic rod. These resistor generally have resistance values that range from 1Ω to 100 kΩ.
VOLTAGE REGULATOR
Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or variable output voltages. They are also rated by the maximum current they can pass. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current ( 'overload protection') and overheating ( 'thermal protection'). Many of the fixed voltage regulator ICs have 3 leads and look like power transistors, such as the 7805 +5V 1A regulator shown on the right. They include a hole for attaching a heatsink if necessary.
Function
Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve and early diodes were actually called valves.
Forward Voltage Drop
Electricity uses up a little energy pushing its way through the diode, rather like a person pushing through a door with a spring. This means that there is a small voltage across a conducting diode, it is called the forward voltage drop and is about 0.7V for all normal diodes which are made from silicon. The forward voltage drop of a diode is almost constant whatever the current passing through the diode so they have a very steep characteristic (current-voltage graph).
Reverse Voltage
When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a very tiny current of a few µA or less. This can be ignored in most circuits because it will be very much smaller than the current flowing in the forward direction. However, all diodes have a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail and pass a large current in the reverse direction, this is called breakdown.
Capacitors
Function
Capacitors store electric charge. They are used with resistors in timing circuits because it takes time for a capacitor to fill with charge. They are used to smooth varying DC supplies by acting as a reservoir of charge. They are also used in filter circuits because capacitors easily pass AC (changing) signals but they block DC (constant) signals.
Capacitance
This is a measure of a capacitor's ability to store charge. A large capacitance means that more charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very large, so prefixes are used to show the smaller values.
Three prefixes (multipliers) are used, µ (micro), n (nano) and p (pico):
• µ means 10-6 (millionth), so 1000000µF = 1F
• n means 10-9 (thousand-millionth), so 1000nF = 1µF
• p means 10-12 (million-millionth), so 1000pF = 1nF
Capacitor values can be very difficult to find because there are many types of capacitor with different labelling systems!
There are many types of capacitor but they can be split into two groups, polarised and unpolarised. Each group has its own circuit symbol.
Electrolytic Capacitors
Electrolytic capacitors are polarised and they must be connected the correct way round, at least one of their leads will be marked + or -. They are not damaged by heat when soldering.
There are two designs of electrolytic capacitors; axial where the leads are attached to each end (220µF in picture) and radial where both leads are at the same end (10µF in picture). Radial capacitors tend to be a little smaller and they stand upright on the circuit board.
It is easy to find the value of electrolytic capacitors because they are clearly printed with their capacitance and voltage rating. The voltage rating can be quite low (6V for example) and it should always be checked when selecting an electrolytic capacitor. If the project parts list does not specify a voltage, choose a capacitor with a rating which is greater than the project's power supply voltage. 25V is a sensible minimum for most battery circuits.
Ultrasonic sensor
Ultrasonic transducers are transducers that convert ultrasound waves to electrical signals or vice versa. Those that both transmit and receive may also be called ultrasound transceivers; many ultrasound sensors besides being sensors are indeed transceivers because they can both sense and transmit. These devices work on a principle similar to that of transducers used in radar and sonar systems, which evaluate attributes of a target by interpreting the echoes from radio or sound waves, respectively. Active ultrasonic sensors generate high-frequency sound waves and evaluate the echo which is received back by the sensor, measuring the time interval between sending the signal and receiving the echo to determine the distance to an object
PROJECT DESCRIPTION
In this Project we use ATMEL-89S52 microcontroller and interfaced with the Ultrasonic Sensor Module for Detecting the Distance of any object from it .this sensor have transmit the sound waves and when sound waves is reflected by any object then calculate the time when wave is back to it and then according to distance formula we have find the distance of object from the sensor.
when any object is come near to this sensor then it will give the Interrupt to microcontroller and microcontroller display this distance to LCD that is used in our project. This complete project work in 5V Dc Power Supply.
COMPONENTS USED
• Lm 7805(Regulator)
• LEDs
• 2 Ceramic capacitors – 33pf
• 2 Electrolytic capacitors – 10uf / 25v and 1000uf/25V
• Four diodes
• 12v transformer
• Microcontroller ATMEL-89S52
• Resistor- 10K
• Crystal Oscillator
• Variable resistor – 10K
• Reset Switch
• Ultrasonic Sensor Module HC - SR04
• PCB
RESISTANCE
Resistance refers to the property of a substance that impedes the flow of electric current. Some substances resist current flow more than other. If a substance offers very high resistance to current flow it is called an insulator. If its resistance to current flow is very low, it is called a conductor. Resistivity refers to the ability of substance to resist current flow. Good conductors have low resistivity and insulators have high resistivity.
Ohm’s Law
George Simon Ohm (1789-1854), a German physicist, formulated the relationships among voltage, current, and resistance into what is referred to as Ohm’s law:
The current in a circuit is directly proportional to the applied potential difference and inversely proportional to the resistance of the circuit.
The International Standard (SI) unit of resistance is the ohm, designated by the Greek letter one ohm of resistance is equal to the resistance of a circuit in which a potential difference of one volt produces a current of one ampere.
Mathematically Ohm’s law is written as:
I = E/R
Where I is the current in amperes, E is the applied voltage (difference in potential) in volts and R is the resistance in ohms.
Therefore, voltage can be calculated using formula:
E = I * R
Resistance can be calculated using the formula:
R = E/I
It is important to note that adjusting voltage or current can not change resistance. Resistance in a circuit is a physical constant and can only be modified by changing components, exchanging resistance for those rated at more or fewer ohms, or by adjusting variable resistors.
Types of Resistors
Resistors come in variety of values and types. The most common type is fixed resistor. Fixed resistor have single value of resistance, which remain constant. There are also variable resistors that can be adjusted to vary or change the amount of resistance n a circuit.
The value of resistance of resistors is given in ohms. Resistors can have values from less than one ohm up to many millions of ohms.
1. Fixed Resistors
The most common fixed resistor is the composition type. The resistance element is made of graphite, or some other form of carbon, and alloy materials. These resistor generally have resistance values that range from 0.1Ω to 22 MΩ.
Another kind of fixed resistor is the wire wound type. The resistance element is usually made of nickel-chromium wire wound on a ceramic rod. These resistor generally have resistance values that range from 1Ω to 100 kΩ.
VOLTAGE REGULATOR
Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or variable output voltages. They are also rated by the maximum current they can pass. Negative voltage regulators are available, mainly for use in dual supplies. Most regulators include some automatic protection from excessive current ( 'overload protection') and overheating ( 'thermal protection'). Many of the fixed voltage regulator ICs have 3 leads and look like power transistors, such as the 7805 +5V 1A regulator shown on the right. They include a hole for attaching a heatsink if necessary.
Function
Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the direction in which the current can flow. Diodes are the electrical version of a valve and early diodes were actually called valves.
Forward Voltage Drop
Electricity uses up a little energy pushing its way through the diode, rather like a person pushing through a door with a spring. This means that there is a small voltage across a conducting diode, it is called the forward voltage drop and is about 0.7V for all normal diodes which are made from silicon. The forward voltage drop of a diode is almost constant whatever the current passing through the diode so they have a very steep characteristic (current-voltage graph).
Reverse Voltage
When a reverse voltage is applied a perfect diode does not conduct, but all real diodes leak a very tiny current of a few µA or less. This can be ignored in most circuits because it will be very much smaller than the current flowing in the forward direction. However, all diodes have a maximum reverse voltage (usually 50V or more) and if this is exceeded the diode will fail and pass a large current in the reverse direction, this is called breakdown.
Capacitors
Function
Capacitors store electric charge. They are used with resistors in timing circuits because it takes time for a capacitor to fill with charge. They are used to smooth varying DC supplies by acting as a reservoir of charge. They are also used in filter circuits because capacitors easily pass AC (changing) signals but they block DC (constant) signals.
Capacitance
This is a measure of a capacitor's ability to store charge. A large capacitance means that more charge can be stored. Capacitance is measured in farads, symbol F. However 1F is very large, so prefixes are used to show the smaller values.
Three prefixes (multipliers) are used, µ (micro), n (nano) and p (pico):
• µ means 10-6 (millionth), so 1000000µF = 1F
• n means 10-9 (thousand-millionth), so 1000nF = 1µF
• p means 10-12 (million-millionth), so 1000pF = 1nF
Capacitor values can be very difficult to find because there are many types of capacitor with different labelling systems!
There are many types of capacitor but they can be split into two groups, polarised and unpolarised. Each group has its own circuit symbol.
Electrolytic Capacitors
Electrolytic capacitors are polarised and they must be connected the correct way round, at least one of their leads will be marked + or -. They are not damaged by heat when soldering.
There are two designs of electrolytic capacitors; axial where the leads are attached to each end (220µF in picture) and radial where both leads are at the same end (10µF in picture). Radial capacitors tend to be a little smaller and they stand upright on the circuit board.
It is easy to find the value of electrolytic capacitors because they are clearly printed with their capacitance and voltage rating. The voltage rating can be quite low (6V for example) and it should always be checked when selecting an electrolytic capacitor. If the project parts list does not specify a voltage, choose a capacitor with a rating which is greater than the project's power supply voltage. 25V is a sensible minimum for most battery circuits.
Ultrasonic sensor
Ultrasonic transducers are transducers that convert ultrasound waves to electrical signals or vice versa. Those that both transmit and receive may also be called ultrasound transceivers; many ultrasound sensors besides being sensors are indeed transceivers because they can both sense and transmit. These devices work on a principle similar to that of transducers used in radar and sonar systems, which evaluate attributes of a target by interpreting the echoes from radio or sound waves, respectively. Active ultrasonic sensors generate high-frequency sound waves and evaluate the echo which is received back by the sensor, measuring the time interval between sending the signal and receiving the echo to determine the distance to an object