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microcontroller based protection of induction motor against voltage fluctuatuions
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CONTENTS
Page no.
ABSTRACT........................................................................................................................i
LIST OF FIGURES:.........................................................................................................ii
LIST OF TABLES:..........................................................................................................iii
CHAPTER 1: INTRODUCTION....................................................................................1
1.1. Introduction...............................................................................................................1
1.2. Aim............................................................................................................................1
1.3. Methodology.............................................................................................................2
1.4. Block diagram...........................................................................................................2
1.5. Siginificance of the work..........................................................................................3
1.6. Description about the project....................................................................................3
1.7. Organisation of report...............................................................................................3
1.8. Conclusion...........................................................................................................................4
CHAPTER 2: INDUCTION MOTOR.............................................................................5
2.1. Introduction...............................................................................................................5
2.2. Principle of operation................................................................................................6
2.3. Starting of induction..................................................................................................6
2.4. General faults in induction........................................................................................7
2.5. Applications..............................................................................................................9
2.6. Conclusion...........................................................................................................................9
CHAPTER 3: MICRO CONTROLLER.......................................................................10
3.1. Introduction.............................................................................................................10
3.2. Features of at89s52.................................................................................................10
3.3. Central processing unit............................................................................................11
3.4. Timers/ counters......................................................................................................11
3.5. Memory organization..............................................................................................12
3.6. Interrupts.................................................................................................................13
3.7. Addressing modes...................................................................................................14
3.8. Architechture of microcontroller at89s52...............................................................15
3.9. Pin configuration.....................................................................................................16
3.10. Ports......................................................................................................................18
3.11. Instruction set of mcs52........................................................................................20
3.12. Programmable clock out.......................................................................................20
3.13. Conclusion.......................................................................................................................20
CHAPTER 4: AUTO-PROTECTION OF INDUCTION MOTOR AGAINST VOLTAGE FLUCTUATIONS.......................................................................................21
4.1. Introduction.............................................................................................................21
4.2. Regulator.................................................................................................................21
4.3. Dual comparator (lm393)........................................................................................22
4.4. Liquid crystal display..............................................................................................24
4.5. Pcb layout................................................................................................................24
4.6. Fault detection circuit..............................................................................................27
4.7. Main circuit diagram...............................................................................................30
4.8. Flow chart...............................................................................................................32
4.9. Program...................................................................................................................33
4.10. Conclusion.......................................................................................................................58
CHAPTER5: EXPERMENTAL RESULTS AND CONCLUSION...........................60
5.1. Result......................................................................................................................60
5.2. Conclusion..............................................................................................................60
5.3. Application..............................................................................................................61
5.4. Future enhancements........................................................................................................61
BIBLIOGRAPHY………………………………………………………..62
APPENDIX-1……………………………………………………………..63
APPENDIX-2……………………………………………………………..68
APPENDIX-3……………………………………………………………..77
ABSTRACT
This Project aims at protection of the three phase Induction motors. The circuit
will take the full control of the motor and it will protect the motor from several faults
such us over voltage and under voltage and the circuit will switch on the motor under
safety conditions. This also protects induction motor from single phasing which is also a
major fault.
The circuit was fully controlled by the microcontroller and the microcontrollers
will continuously monitors the voltages of the three phases and if the voltage goes
abnormal then it will switch off the motor until they are normal. All the conditions are
displayed by it over the LCD display. In our project we are using the popular 8 bit
microcontroller AT89C52. It is a 40 pin microcontroller.
The protection of induction motor with microcontroller has flexibility to switch
off at required time, monitors phases of motor at every time and also every motoring
action is known through LCD display. It also protects motor from single phasing as its
maintenance cost is also cheap.
i
LIST OF FIGURES:
Figure No. Title Page No.
1.1 Block diagram of automatic voltage control of IM using Microcontroller
3.1 Architecture of Microcontroller AT89S52
3.2 Pin diagram of AT89S52
4.1 Regulator
4.2 Dual comparator LM393
4.3 LCD Display
4.4 PCB Layout
4.5 Fault detection circuit
4.6 Three phase fault detection circuit
4.7 Circuit diagram of Automatic Voltage Control of IM using Microcontroller
4.8 Flow Chart
ii
LIST OF TABLES:
Table No Title Page No
3.1 Interrupt source service routine starting address
3.2 Pin Description of AT89S52
3.3 Port 3 Alternate Functions
iii
CHAPTER 1
INTRODUCTION
1.1 INTRODUCTION
The manner in which the use of microcontrollers is shaping our lives in breath
taking. Today this versatile device can be found in a variety of control applications. TVs,
VCRs, CD players, microwave ovens, automotive engines are some of these.
A Microcontroller unit (MCU) uses microprocessor as its central processing unit
(CPU) and it Incorporates memory, Timing reference, I/O peripherals etc., on same chip.
Limited computational capabilities and enhanced I/O are special features.
In our project the microcontroller is used to control the three phase induction
motor.
The motor protection is required as day to day life induction motor usage
increases a lot as it has some specific merits. The circuit was fully controlled by the
microcontroller and the micro controllers will continuously monitors the voltages of the
three phase and if the voltages goes abnormal then it will switch off the motor until they
are normal.
Its not only protect motor from transient voltages, it also switch on the motor
automatically when power comes without manual requirement and off the motor after
predetermined time. This motor is manually monitoring is difficult so automatic
protection of induction motor has such an importance.
1.2. AIM
This Project aims protection of three phase Induction motors and to start and stop
the motor automatically. The circuit will take full control of the motor and it will protect
the motor from several faults such as over voltage and under voltage and the circuit will
switch on the motor under safety conditions. This also protects Induction motor from
single phasing which is also a major fault.
1
1.3. METHODOLOGY
In this project we are using dual comparator to compare over/under voltages with
the present voltage and send signal to microcontroller if the voltage goes beyond the
range. Here we are using LM393 dual comparator.
Addition to this we are using two switches one for auto on and another one for
auto off. Here the motor will run automatically when auto on is set and it will start the
motor automatically after a particular time if off is set.
According to the program written into the microcontroller the circuit will
automatically on/off the motor. The prime use of the microcontroller is to protect the
motor from over and under voltage and to start/stop the motor automatically.
Microcontroller send signal to the relay which is connected to starter of motor. According
to the signal from the controller the relay will start/stop the motor.
1.4. BLOCK DIAGRAM
The main block diagram of automatic voltage control of Induction motor using
microcontroller is shown in fig:
Fig 1.1 Block diagram of automatic voltage control of IM using microcontroller
2
Starter3 phase over/under voltage detector
OFF Timer Switch LCD Display
Stop Relay
Start Relay
Micro Controller AT89S52 Induction
Motor
1.5. SIGINIFICANCE OF THE WORK
This project can be used to project the motor from undesired voltages .The main
applications of the project is in industrial and agriculture fields to protect the motor and it
also starts and stop the motor automatically.
1.6. DESCRIPTION ABOUT THE PROJECT
Whenever over/under voltages occurs then the dual comparator LM393 will
predict and sends the signal to the microcontroller .The dual comparator LM393 is
initially set to the range between 180V to 260V, if the voltage goes beyond the specified
range it will send the signal to the microcontroller .According to the program written into
the microcontroller AT89S52 and it will send the signal to the relay, and then relay stops
the motor.
The circuit was fully controlled by the microcontroller and the microcontrollers
will continuously monitors the voltages of the three phase and if the voltage goes
abnormal then it will switch off the motor until they are normal. All the conditions are
displayed it over the LCD display.
Auto ON and Auto OFF switches are push to on switches, which will be ON only
until they are held at pressed state once they are released the switch gets opened. The
function of auto switch is that when it is pressed and released the motor is turned off after
providing a delay which is dictated by the positioning of the rotary switch. The physical
functioning of the auto on switch is that once the auto on switch is set and if the supply is
provided and also voltages are in normal condition then the motor start automatically.
1.7. ORGANISATION OF REPORT
Chapter -2 deals with Induction motor which includes construction and operation.
Types of faults in Induction motor, starting methods of Induction motor.
(Reference 1: Electrical machines by I J NAGRATH, D P KOTHARI)
(Reference 2: www.google.com)
(Reference 3: www.alldatasheets.com)
3
Chapter -3 Deals with micro controller which includes the pin description and instruction
set to develop the program for automatic voltages control of induction motor. Here We
are using the microcontroller AT89S52 for automatic voltages control of Induction
motor.
(Reference 1: www.electronicsforyou.com )
(Reference 2: www.google.com)
(Reference 3: www.alldatasheets.com)
(Reference 4: www.atmel.com )
(Reference 5: www.8052.com )
Chapter- 4 Deals with dual comparator, Regulator and LCD includes the circuit operation
of automatic voltages control of Induction motor using Microcontroller.
(Reference 1: www.microcontroller.net )
(Reference 2: www.google.com)
(Reference 3: www.electronicsforyou.com)
(Reference 4: www.alldatasheets.com)
(Reference 5: www.philipssemiconductors.com)
1.8. CONCLUSION
This project can be used with the three phase Induction motor. The circuit will
take full control of the motor and it will protect the motor from several faults such as over
voltage and under voltages and the circuit will switch on the motor under safety
conditions.
4
CHAPTER 2
INDUCTION MOTOR
2.1. INTRODUCTION
Induction Motor is one kind of AC motor where power is supplied to the rotating
device by induction. An electric motor converts electrical power to mechanical power in
its rotor (rotating part). There are several ways to supply power to the rotating part of the
motor. In a DC motor this power is supplied to the armature directly from a DC source.
But in an A.C. Motor this power is induced in the rotating device. An induction motor
can be called a rotating transformer because the stationary (stationary part) is essentially
the primary side of the transformer and the rotor (rotating part) is the secondary side.
Induction motors are widely used, especially polyphase induction motors, which are
frequently used in industrial drives.
Induction motors are now the preferred choice for industrial motors due to their
rugged construction, lack of brushes like in DC motors and they have ability to control
the speed due to rapid developments in power electronics.
There are two types of motors
1. Squirrel cage motor
2. Slip ring motor
Of the two the squirrel cage induction motor is most widely used because of its
simple construction, high reliability and low maintenance cost. The rotor bars in squirrel
cage induction motors are not straight but have some skew to reduce noise and harmonics
Due to the flexibility in the slip ring induction motor to vary the rotor resistance it is used
in the applications involving high starting torque and speed control .But it has high initial
cost, high maintenance cost.
5
2.2. PRINCIPLE OF OPERATION
The basic difference between an induction motor and a synchronous AC motor is
that in the latter a current is supplied into the rotor (usually a DC current) which in turn
creates a (circular uniform) magnetic field around the rotor. The rotating magnetic field
of the stator will impose an electromagnetic torque on the still magnetic field of the rotor
causing it to move (about a shaft) and rotation of the rotor is produced. It is called
synchronous because at steady state the speed of the rotor is the same as the speed of the
rotating magnetic field in the stator.
By way of contrast, the induction motor does not have any direct supply onto the
rotor; instead, a secondary current is induced in the rotor. To achieve this, stator windings
are arranged around the rotor so that when energized with a polyphase supply they create
a rotating magnetic field pattern which sweeps past the rotor. This changing magnetic
field pattern induces current in the rotor conductors. This current interacts with the
rotating magnetic field created by the stator and in effect causes a rotational motion on
the rotor.
However, for these currents to be induced, the speed of the physical rotor must be
less than the speed of the rotating magnetic field in the stator, or else the magnetic field
will not be moving relative to the rotor conductors and no currents will be induced. If by
some chance this happens, the rotor typically slows slightly until a current is re-induced
and then the rotor continues as before. This difference between the speed of the rotor and
speed of the rotating magnetic field in the stator is called slip. It is unit less and is the
ratio between the relative speed of the magnetic field as seen by the rotor (the slip speed)
to the speed of the rotating stator field. Due to this an induction motor is sometimes
referred to as an asynchronous machine.
2.3. STARTING OF INDUCTION
In a three phase induction motor, the induced emf in rotor circuit depends on the
slip of the induction motor and the magnitude of the rotor current depends upon this
induced emf. When the motor is started, the slip is equal to 1 as the rotor speed is zero, so
6
the induced emf in rotor is large. As a result, a very high current flows through the rotor.
This is similar to a transformer with the secondary coil short circuited, which causes the
primary coil to draw a high current is drawn by the stator, on the order of 5 to 9 times the
full load current. This high current can damage the motor windings and because it causes
heavy line voltage drop, other appliances connected to the same line may be affected by
the voltage fluctuation. To avoid such effects, the starting current should be limited. A
starter is a device which limits the starting current by providing reduced voltage to the
motor. Once the rotor speed increases, the full rated voltage is given to it.
2.3.1. TYPES OF STARTERS
Direct on line starter
Autotransformer starter
Star Delta starter
Stator Resistance starter
2.4. GENERAL FAULTS IN INDUCTION
There are various faults occurring in 3 phase induction motor, but in our project
we have protected the induction motor from the following faults only i.e.
1. Voltage imbalances.
2. Single phasing.
2.4.1. EFFECTS OF UNBALANCED SUPPLY
The effect of unbalanced voltages on polyphase induction motors is equivalent to
the introduction of 'negative sequence voltage' having a rotation opposite to that
occurring with balanced voltages. This negative sequence voltage produces in the air gap
a flux rotating against the rotation of the rotor, tending to produce high current. A small
negative sequence voltage may produce in the windings currents considerably in excess
of those present under balanced voltage conditions. "The voltage unbalance (or negative
sequence voltage) in percent may be defined as follows: Per cent voltage unbalance =
Max. Voltage deviation from Avg. voltage x 100 Average voltage.
7
Example: With voltages of 220, 215, and 210, the average is 215, the maximum deviation
from the average is and the percent unbalance is 5 x 100, or 2.3 per cent 215. A relatively
small unbalance in voltage will cause considerable increase in temperature rise in the
phase with the highest current; the percentage increase in temperature rise will be
approximately two times the square of the percentage voltage unbalance. The increase
losses and, consequently, the increase in average heating of the whole winding will be
slightly lower than the winding with the highest current. To illustrate the severity of this
condition, an approximate 3.5 percent voltage unbalance will cause an approximate 25
per cent increase in temperature rise. The locked rotor current will be unbalanced to the
same degree that the voltages are unbalanced but the locked rotor KVA will increase only
slightly. "The currents at normal operating speed with the unbalanced voltages will be
greatly unbalanced in the order of approximately 6 to 10 times the voltage unbalance.
This introduces a complex problem in selecting the proper overload protective devices,
particularly since devices selected for one set of unbalanced conditions may be
inadequate for a different set of unbalanced voltages, increasing the size of the overload
device is not the solution in as much as protection against heating from overload and
single phase operation is lost.”
If it is determined that the problem is one of voltage unbalance, the next step is to find
out what caused unbalanced condition. These are some of the causes:
Unequal loading per phase on the transformer serving the motor;
Single phasing, such as would be caused by Blown fuse on the primary of the
transformer serving the motor;
Unequal Transformer tap settings;
Unequal transformer impedances (impedances can range from 1.6 to 6 per
cent;
Capacitor banks with fuse blown or with unequal capacity per phase;
Voltage regulators out of step or calibration;
Transformer bank connected in configuration that inherently provides poor
regulation, such as open delta or T-T connection. Of these, the most common
8
items are 1 and 2. Item 2 (open phase) can be quite difficult to detect if a high
percentage of the load connected to the transformer secondary is rotating
equipment, in such cases, the open phase may remain at approximately full
potential.
In fact, the large-scale negative sequence currents in induction motor result from
slight unbalanced voltage, causing overheating, shaft vibration, noise, derating and
additional losses, and hence reduce its lifetime and performance.
2.4.2 SINGLE PHASING
It is well known that a three-phase induction motor will continue to operate when
a disturbance of some sort causes the voltages supplied to the motor to become single-
phase. The single-phasing can occur as a result of a fuse blowing or protective device
opening on one phase of the motor. Other possibilities include feeder or step-down
transformer fuses blowing. Even though the motor will continue to operate in this
condition, the motor will heat up very quickly and it is essential that the motor be
removed from service by the opening of a motor circuit breaker or some other type of
protective device. This paper will describe three different ways in which an induction
motor will operate in a single-phase condition. For purposes of this paper "single-phase"
will include any condition in which the three line-to-line voltage phasors appear on the
same line.
2.5. APPLICATIONS
The induction motor has wide applicability as a motor in industry and its single
phase form in several domestic applications. A wide range of speed control is possible
only by circuitry using silicon controlled rectifiers.
2.6. CONCLUSION
The induction motor is an important class of electrical machine. Day to day it has
more than 85% of industrial usage because of its simple construction and reliable. By
having these advantages in agricultural and industrial fields we are protecting Induction
Motor from over/under voltages and single phasing.
9
CHAPTER 3
MICRO CONTROLLER
3.1. INTRODUCTION
The AT89S52 is a low-power, high-performance CMOS 8-bit microcomputer
with 8 Kbytes of Flash Programmable and Read Only Memory (PEROM). The device is
manufactured using Atmel’s high-density nonvolatile memory technology and is
compatible with the industry standard 80C51 instruction set and pinout. The on-chip
Flash allows the program memory to be reprogrammed in-system or by a conventional
nonvolatile memory programmer.
By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel
AT89S52 is a powerful microcontroller which provides a highly-flexible and cost
effective solution to many embedded control applications.
The AT89S52 provides the following standard features: 8K bytes of Flash, 256
bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit
timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-
chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic
for operation 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 con-tents but freezes the oscillator, disabling all other chip functions until the next
interrupt or hardware reset.
3.2. Features of AT89S52
Compatible with MCS-51 Products
8K Bytes of In-System Programmable (ISP) Flash Memory
Endurance: 1,000 Write/Erase Cycles
4.0V to 5.5V Operating Range
10
Fully Static Operation: 0 Hz to 33 MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Interrupt Recovery from Power-down Mode
Eight Interrupt Sources
Full Duplex UART Serial Channel
Low-power Idle and Power-down Modes
3.3. CENTRAL PROCESSING UNIT
The CPU is the brain of the microcontrollers reading user’s programs and
executing the expected task as per instructions stored there in. Its primary elements are an
8-bit Arithmetic Logic Unit (ALU), Accumulator (Acc), few more 8 bit registers, B
register, stack pointer (SP), Program Status Word (PSW) and 16 bit registers, Program
Counter (PC) and Data Pointer Register (DPTR).
The ALU (Acc) performs arithmetic and logic functions on 8 bit input variables.
Arithmetic operations include basic addition, subtraction, multiplication and division.
Logical operations are AND, OR, Exclusive OR as well as rotate, clear, complement and
etc. Apart from all the above, LAU is responsible in conditional branching decisions, and
provides a temporary place in data transfer operations within the device.
B register is mainly used in multiply and divide operations. During execution, B
register either keeps one of the two inputs or then retains a portion of the result. For other
instructions, it can be used as another general purpose register.
Program status word keeps the current status of the ALU in different bits.
3.4. TIMERS/ COUNTERS
8052 has three 16 bit Timers/ Counters capable of working in different modes.
Each consists of a ‘High’ byte and a ‘Low’ byte which can be accessed under software.
There is a mode control register and a control register to configure these timers/ counters
in number of ways.
11
These timers can be used to measure time intervals, determine pulse widths or
initiate events with one microsecond resolution up to a maximum of 65 millisecond
(corresponding to 65, 536 counts). Use software to get longer delays. Working counter,
they can accumulate occurrences of external events (from DC to 500 KHz) with 16 bit
precision.
3.5. MEMORY ORGANIZATION
The 8052 architecture provides both on-chip memory as well as off-chip memory
expansion capabilities. It supports several distinctive ‘physical’ address spaces,
functionally separated at the hardware level by different addressing mechanisms, read
and write controls signals or both:
On chip Program Memory
On chip Data Memory
Off chip program memory
Off chip Data Memory
On chip Special Function Registers
The Program Memory area (EPROM incase of external memory or Flash/
EPROM in case of internal one) is extremely large and never lose information when the
power is removed. Program Memory is used for information needed each time power is
applied: Initialization values, calibration data, keyboard lookup tables etc., along with
the program itself. The program memory has a 16 bit address and any particular memory
location is addressed using the 16 bit program counter and instructions which generate a
16 bit address.
On chip data memory is smaller and therefore quicker than Program Memory and
it goes into a random state when power is removed. On chip RAM is used for variables
which are calculated when the program is executed.
In contrast to the Program Memory, On chip Data Memory accesses need a single
8 bit value (may be a constant or another variable) to specify a unique location. Since 8
bits are more than sufficient to address 128 RAM locations, the On chip RAM address
generating register is single byte wide.
12
Different addressing mechanisms are used to access these different memory
spaces and this greatly contributes to microcomputer’s operating efficiency.
The 64 Kbyte program memory space consists of an internal and an external
memory portion. If the EA pin is held high, the 8051 executes out of internal Program
Memory unless the address exceeds 0FFFH and locations 1000H through FFFFH are then
fetched from external Program Memory. If the EA pin held low, the 8051 fetches all
instructions from the External Program Memory. In either case, the 16 bit Program
Counter is the addressing mechanism.
The Data Memory address space consists if an internal and an external memory
space. External Data Memory is accessed when a MOVX instruction is executed.
Apart from On-chip Data Memory of size 128/256 bytes, total size of Data
Memory can be expanded up to 64K using external RAM devices.
Total internal Data Memory is divided into three blocks:
Lower 128 bytes.
Higher 128 bytes.
Special Function Register space.
Higher 128 bytes are available only in 8032/8052 devices.
Even through the upper RAM area and SFR area share address locations, they are
accessed through different addressing modes. Direct addresses higher than 7FH access
SFR memory space and indirect addressing above 7FH access higher 128 bytes (in
8032/8052).
3.6. INTERRUPTS
The 8052 has five interrupt sources: one from the serial port when a transmission
or reception operation is executed; two from the timers when overflow occurs and two
come from the two input pins INT0, INT1. Each interrupt may be independently enabled
or disabled to allow polling on same sources and each may be classified as high or low
priority.
13
A high priority source can override a low priority service routine. These options
are selected by interrupt enable and priority control registers, IE and IP.
When an interrupt is activated, then the program flow completes the execution of
the current instruction and jumps to a particular program location where it finds the
interrupt service routine. After finishing the interrupt service routine, the program flows
return to back to original place.
The Program Memory Address, 0003H is allocated to the first interrupt and next
seven bytes can be used to do any task associated with that interrupt.
INTERRUPT SOURCE SERVICE ROUTINE STARTING ADDRESS
External 0 0003H
Timer/counter 0 000BH
External 1 0013H
Timer/counter 1 001BH
Serial port 0023H
Table 3.1 Interrupt source service routine starting address
3.7. ADDRESSING MODES
8052’s assembly language instruction set consists of an operation mnemonic and
zero to three operands separated by commas. In two byte instructions the destination is
specified first, and then the source. Byte wide mnemonics like ADD or MOV use the
Accumulator as a source operand and also to receive the result.
The 8052 supports five types of addressing modes:
Register Addressing
Direct Addressing
Register Indirect Addressing
Immediate Addressing
Index Addressing
14
3.8. ARCHITECHTURE OF MICROCONTROLLER AT89S52
Fig 3.1 Architecture of Microcontroller AT89S52
3.9. PIN CONFIGURATION
15
Fig 3.2 pin diagram of
AT89S52
16
3.9.1. PIN DESCRIPTION OF AT89S52
Pin. No Pin name Pin description
1,7 Port 1 Input/output Pins9 RST Reset Input10 RXD Receive Data11 TXD Transmit Data12 INT0 Interrupt 013 INT 1 Interrupt 114 T0 Timer 0 input15 T1 Timer 1 input16 WR Write Strobe17 RD Read Strobe18 XTAL 2 Crystal Input 219 XTAL 1 Crystal Input 120 Vss Ground21 A8 Address 822 A9 Address 923 A10 Address 1024 A11 Address 1125 A12 Address 1226 A13 Address 1327 A14 Address 1428 A15 Address 1529 PSEN Program Store Enable30 (PROG)ALE Address Latch Enable (EPROM Program Plus)31 (Vpp)/EA External enable(EPROM Program voltage)32 AD7 Address/Data 733 AD6 Address/Data 634 AD5 Address/Data 535 AD4 Address/Data 436 AD3 Address/Data 337 AD2 Address/Data 238 AD1 Address/Data 139 AD0 Address/Data 040 Vcc +5v
Table 3.2. Pin Description of AT89S52
17
3.10. PORTS
Port 0
Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can
sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high
impedance inputs. Port 0 can also be configured to be the multiplexed low-order
address/data bus during accesses to external program and data memory. In this mode, P0
has internal pull-ups. Port 0 also receives the code bytes during Flash programming and
outputs the code bytes during program verification. External pull-ups are required during
program verification.
Port 1
Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 1 output
buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are
pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that
are externally being pulled low will source current (IIL) because of the internal pull-ups.
In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count
input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown
in the following table. Port 1 also receives the low-order address bytes during Flash
programming and verification.
Port 2
Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 2 output
buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are
pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that
are externally being pulled low will source current (IIL) because of the internal pull-ups.
Port 2 emits the high-order address byte during fetches from external program
memory and during accesses to external data memory that uses 16-bit addresses (MOVX
@ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s.
During accesses to external data memory that uses 8-bit addresses (MOVX @ RI), Port 2
18
emits the contents of the P2 Special Function Register. Port 2 also receives the high-order
address bits and some control signals during Flash programming and verification.
Port 3
Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. The Port 3 output buffers
can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the
internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being
pulled low will source current (IIL) because of the pull-ups. Port 3 receives some control signals
for Flash programming and verification. Port 3 also serves the functions of various special
features of the AT89S52, as shown in the following table.
Port Pin Alternate Functions
P3.0 RXD (serial input port)
P3.1 TXD (serial output port)
P3.2 INT0 (external interrupt 0)
P3.3 INT1 (external interrupt 1)
P3.4 T0 (timer 0 external input)
P3.5 T1 (timer 1 external input)
P3.6 WR (external data memory write strobe)
P3.7 RD (external data memory read strobe)
Table 3.3 Port3 Alternate Functions
Port 3 also receives some control registers for Flash Programming and
Programming verification.
19
3.11. INSTRUCTION SET OF MCS52
1. ARITHEMATIC OPERATIONS
2. LOGICAL OPERATIONS
3. DATA TRANSFER
4. BOOLEAN VARIABLE MANIPULATIO
3.12. PROGRAMMABLE CLOCK OUT
A 50% duty cycle clock can be programmed to come out on P1.0. This pin,
besides being a regular I/O pin, has two alternate functions. It can be programmed to
input the external clock for Timer/Counter 2 or to output a 50% duty cycle clock ranging
from 61 Hz to 4 MHz (for a 16MHz operating frequency). To configure the
Timer/Counter 2 as a clock generator, bit C/T2 (T2CON.1) must be cleared and bit T20E
(T2MOD.1) must be set. Bit TR2 (T2CON.2) starts and stops the timer. The clock-out
frequency depends on the oscillator frequency and the reload value of Timer 2 capture
registers (RCAP2H, RCAP2L), as shown in following equation.
3.13. CONCLUSION
The AT89S52 is a low-power, high-performance CMOS 8-bit microcomputer
with 8 Kbytes of Flash Programmable and Read Only Memory (PEROM). It is easy to
develop the program for the protection of motor from over and under voltages. The
output of the microcontroller is applied to the relays to switch ON and OFF the motor.
20
CHAPTER 4
AUTO-PROTECTION OF INDUCTION MOTOR AGAINST VOLTAGE FLUCTUATIONS
4.1 INTRODUCTION
The motor voltage control using the microcontroller mainly includes fault
detection circuit to detect abnormal voltage conditions and the circuit was fully controlled
by the microcontroller and the microcontroller will continuously monitors the voltages of
the three phases and if the voltages goes abnormal then it will switch off the motor until
they are normal.
4.2 REGULATOR
The LM7805 monolithic 3-terminal voltage regulator employs internal current-
limiting, thermal shutdown and safe-area compensation, making them essentially
indestructible. If adequate heat sinking is provided, they can deliver over 1.0A output
current.
4.2.1 PIN CONFIGURATION
Fig 4.1. Regulator
21
They are intended as fixed voltage regulators in wide range of applications
including local (on-card) regulation for elimination of noise and distribution of noise and
distribution problems associated with single-point regulation for elimination. In addition
to use as fixed voltage regulators, these devices can be used with external components to
obtain adjustable output voltages and currents. Considerable was expended to make the
entire series of regulators easy to use and minimize the number of external components.
It is not necessary to bypass the output, although this does improve transient response.
Input bypassing is needed only if the regulator is located far from the filter capacitor of
the power supply.
4.3 DUAL COMPARATOR (LM393)
The LM393 series consists of two independent precision voltage comparators with
an offset voltage specification as low as 2.0 mV max for two comparators which were
designed specifically to operate from a single power supply over a wide range of
voltages. Operation from split power supplies is also possible and the low power supply
current drain is independent of the magnitude of the power supply voltage. These
comparators also have unique characteristics in that the input common-mode voltage
range includes ground, even though operated from a single power supply voltage.
Application areas include limit comparators, simple analog to digital converters,
pulse, square wave and time delay generators, wide range VCO, MOS clock timers,
multivibrators and high voltage digital logic gates. The LM193 series was designed to
directly interface with TTL and CMOS. When operated from both plus and minus power
supplies, the LM193 series will directly interface with MOS logic where their low power
drain is a distinct advantages over standard comparators
4.3.1 FEATURES
Wide supply
o --- Voltage range: 2.0V to 36V
o --- Single or dual supplies: ±1.0V to ±18V
Very low supply current drain (0.4mA) --- independent of supply voltage
Low input biasing current: 25nA
Low input offset current: ±5nA
22
Maximum offset voltage: ±3mV
Input common-mode voltage range includes ground
Different input voltage range equal to the power supply voltage
Low output saturation voltage: 250mV at 4mA
Output voltage compatible with TTL,DTL,ECL,MOS and CMOS logic systems
Available in the 8-BUMP(12 mil) micro SMD package
4.3.2. PIN DIAGRAM OF LM393
Fig 4.2. Pin Diagram of Dual Comparator LM393
23
4.4 LIQUID CRYSTAL DISPLAY
The most commonly used Character based LCDs are based on Hitachi's HD44780
controller or other which are compatible with HD44580. In this tutorial, we will discuss
about character based LCDs, their interfacing with various microcontrollers, various
interfaces (8-bit/4-bit), programming, special stuff and tricks you can do with these
simple looking LCDs which can give a new look to your application.
Fig. 4.3. LCD Display
The most commonly used LCDs found in the market today are 1 Line, 2 Line or 4
Line LCDs which have only 1 controller and support at most of 80 characters, whereas
LCDs supporting more than 80 characters make use of 2 HD44780 controllers.
Most LCDs with 1 controller has 14 Pins and LCDs with 2 controller has 16 Pins
(two pins are extra in both for back-light LED connections).
To send data we simply need to select the data register. Everything is same as the
command routine. Following are the steps:
Move data to LCD port
Select data register
Select write operation
Send enable signal
Wait for LCD to process the data
Keeping these steps in mind we can write LCD command routine as.
The equivalent C code Keil C compiler. Similar code can be written for SDCC.
4.5 PCB LAYOUT
24
Fig. 4.4. PCB Layout.
4.5.1 FABRICATION DETAILS
The fabrication of all the demonstration units is carried in the following sequence.
1. Finalizing the total circuit diagram, listing out the components and their sources
of procurement.
2. Procuring the components and testing the components.
3. Making layout, preparing the interconnection diagram as per the circuit diagram,
preparing the drilling details, cutting the laminate to the required size
4. Drilling the holes on the board as per the components layout, painting the tracks
on the board as per the inter connection diagram.
25
5. Removing the un-wanted copper other than track portion. Then cleaning the board
with water, and solder coating the copper tracks to protect the tracks from rusting
or oxidation due to moisture.
6. Assembling the components as per the components layout of the circuit diagram
and soldering components
7. Integrating the total unit inter wiring the unit and final testing the unit. Keeping it
ready for demonstration.
4.5.2 PCB FABRICATION PROCEDURE
The basic material in the manufacture of PCB is copper cladded laminate. The
laminate consists of two or more layers insulating reinforced materials bonded together
under hat and pressure by thermo setting resins used are phenolic or epoxy. The
reinforced materials used are electrical grade paper or woven glass cloth. The laminates
are manufactured by impregnating thin sheets of reinforced materials with the required
resin. The laminates are divided in to various grades by national electrical manufacturers
association (NEMA). The nominal overall thickness of laminate normally used in PCB
industry is 1.6mm with copper cladding on one or two sides.
The next stage in the PCB fabrication is artwork preparation. The artwork (master
drawing) is essentially a manufacturing tool used in the fabrication of PCB’s. It defines
the pattern to be generated on the board. Since the artwork is the first of many process
steps in the fabrication of PCB’s. Normally, in industrial applications the artwork is
drawn on an enlarged scale and photographically reduced to required size. It is not only
easy to draw the enlarged dimensions but also the errors in the artwork correspondingly
get reduced during photo reduction. For ordinary application of simple single sided
boards artwork is made on ivory art paper using drafting aids. After taping on a art paper
and photography the image of the photo given is transformed on silk screen printing.
After drying the paint, the etching process is carried out. This is done after drilling of the
holes on the laminate as per the components layout. The etching is the process of
chemically removing unwanted copper from the board.
26
The next stage after PCB fabrication is solder making the board to prevent tracks
from corrosion and rust formation. Then the components will be assembled on the board
as per the components layout.
The next stage after assembling is the soldering the components. The soldering
may be defined as process where in joining between metal parts is produced by heating to
suitable temperatures using non ferrous filler metals has melting temperatures below the
melting temperatures of the metals to be joined. This non-ferrous intermediate metal is
called solder. The solders are the alloys of lead and tin.
4.6. FAULT DETECTION CIRCUIT
Fig 4.5 Fault detection circuit
The basic functioning of the fault detection circuit can be explained as follows.
The center tapped step down transformer is supplied on the primary side from one of
three phases of the supply and its output voltage is rectified by a full wave rectifier. The
output from the rectifier is fed to the two operational amplifiers through a capacitor.
During the normal working conditions without any faults the zener diode connected to
the inverting and non-inverting terminals of the operational amplifiers IC2a and IC2b
27
respectively will be charged to a voltage of 4.2v and the output voltage of the two
opamps will be zero. This voltage across zener diode which remains constant is supplied
to the two opamps as a reference voltage. Of the two opamps one will be operating in
inverting mode (IC2a) and the other in non-inverting mode (IC2b). When the condition of
over voltage occurs, the voltage at the non inverting terminal of the opamp, IC2b will be
more than 4.2 volts as a result of this the output voltage of this opamp will be high and
this error signal will be fed to the micro controller which trips the relay and thus
disconnects the motor from the supply. Similarly the opamp (IC2a) sends an error signal
during under voltage condition.
Similar circuits are used for other two phases. The total fault detection circuit
shown below.
28
Fig 4.6. Three phase fault detection circuit
29
4.7. MAIN CIRCUIT DIAGRAM
Fig 4.7. Circuit Diagram of Automatic Voltage Control of IM using Microcontroller
30
4.7.1. CIRCUIT EXPLANATION
The Circuit diagram consists of three voltage sensor circuits and a relay driver
circuit, power supply circuit and the Microcontroller circuit.
The Main part of the above circuit diagrams is the Microcontroller AT89S52. The
Microcontroller will switch on the motor only the following conditions are satisfied.
If the three phase voltage was normal
If all the phases are present
The Three phase voltages are checked by dual opamp IC LM393. It checks the
input voltage with the reference voltage. The off time was set by the rotary switch for ½
hr to 2hr.
For driver the relay we are using NPN transistor is used as an current amplifier.
The Microcontroller will control the whole circuit according to program burned on its
ROM. All the conditions are displayed over the LCD display.
The power supply section is the important one. It should deliver constant output
regulated power supply for successful working of the project. An 0-12V/500mA
transformer is used for our purpose the primary of this transformer is connected into main
supply through on/off switch and fuse for protecting from overload and short circuit
protection. The secondary is connected to the diodes convert from 12V AC to 12V DC
voltage. Which is further regulated to +5v, by using IC 7805.
31
4.8. FLOW CHART
32
START
SWITCH OFF MOTOR AND ALL LEDs
SWITCH ON MOTOR OFF
RELAY
SWITCH ON MOTOR ON
RELAY
CHECK ROTATOR SWITCH STATUS
CALL APPROXIMATE
DELAY
CHECK PHASE
VOLTAGES
CHECK PHASE
VOLTAGES
CHECK AUTO
ON
CHECK AUTO OFF
ABNORMAL
NORMAL
PRESSED
NOT PRESSED
ABNORMAL
NORMAL
PRESSED
NOT PRESSED
Fig 4.8. Flow Chart
4.9. PROGRAM
The actual used for programming the micro controller is presented below.
INCLUDE REG_52.PDF
PH1 EQU P3.0
PH2 EQU P3.1
PH3 EQU P3.2
LED1 EQU P1.0 ; AUTO ON
LED2 EQU P1.1 ; AUTO OFF
LED3 EQU P1.2 ; MOTOR
; ONRLY EQU P2.0
OFFRLY EQU P2.1
AUTOON EQU P2.6
AUTOOFF EQU P2.7
TIM1 EQU P2.2
TIM2 EQU P2.3
TIM3 EQU P2.4
TIM4 EQU P2.5
; ***LCD CONTROL***
LCD_RS EQU P0.0 ; LCD REGISTER SELECT LINE
LCD_E EQU P0.1 ; LCD ENABLE LINE
33
LCD_DB4 EQU P0.3 ; PORT 1 IS USED FOR DATA
LCD_DB5 EQU P0.4 ; USED FOR DATA
LCD_DB6 EQU P0.5 ; FOR DATA
LCD_DB7 EQU P0.6 ; FOR DATA
; ***CURSOR CONTROL INSTRUCTIONS***
OFFCUR EQU 0CH
BLINKCUR EQU 0DH
; ***DISPLAY CONTROL INSTRUCTIONS***
CLRDSP EQU 01H
ONDSP EQU 0CH
; ***SYSTEM INSTRUCTIONS***
CONFIG EQU 28H ; 4-BIT DATA,2 LINES,5X7 MATRIX LCD
ENTRYMODE EQU 6 ; INCREMENT CURSOR DON'T SHIFT DISPLAY
; ---------==========----------==========---------=========---------
DSEG ; this is internal data memory
ORG 20H ; Bit addressable memory
34
FLAGS: DS 1
LD1 BIT FLAGS.0
LD2 BIT FLAGS.1
MOT BIT FLAGS.2
NEW: DS 1
NEW1 BIT NEW.0
NEW2 BIT NEW.1
NEW3 BIT NEW.2
NEW4 BIT NEW.3
NEW5 BIT NEW.4
MOTT BIT NEW.5
TIM: DS 1 ; scrolling display
SCRL: DS 1 ; count for scr disp
OFF_TIME: DS 1
CSEG ; Code begins here
;---------==========----------==========---------=========---------
; PROCESSOR INTERRUPT AND RESET VECTORS
;---------==========----------==========---------=========---------
ORG 00H ; Reset
JMP MAIN
35
ORG 001BH ; Timer Interrupt1
JMP SCROLL
; ---------==========----------==========---------=========---------
; Main routine. Program execution starts here.
; ---------==========----------==========---------=========---------
MAIN:
MOV SP,#60H
MOV FLAGS,#00H
MOV NEW,#00H
MOV OFF_TIME,#00H
CLR OFFRLY
SETB LED1
SETB LED2
SETB LED3
CALL RESETLCD4
CALL INITLCD4
CALL TITLES
SETB NEW2
MOV TMOD,#11H ; Scrolling Display
MOV TL1,#08H
MOV TH1,#01H
SETB ET1
MOV SCRL,#00H
36
MOV TIM,#120
SETB TR1
SETB EA
UP: SETB PH1 ;
SETB PH2
SETB PH3
SETB AUTOON
SETB AUTOOFF
; Chk if motor is on
JNB AUTOON, HJ1 ; chk auto on
JNB AUTOOFF, HJ2 ; chk auto off
CALL DISP
JNB MOT, UP
JNB PH1, MOTOR_OFF
JB PH2, MOTOR_OFF
JB PH3, MOTOR_OFF
AJMP UP
UP4: JNB AUTOON,$ ;DEBOUNCE FOR AUTO ON KEY
CALL DELAY1
JNB AUTOON,$
SETB LED1
37
AJMP UP
HJ1: JB MOT, UP
; AUTO ON
JNB AUTOON,$
CALL DELAY1
JNB AUTOON,$
CLR LED1
UP3: JNB AUTOON,UP4
SETB NEW4
CALL DISP
JNB PH1,UP3
JB PH2,UP3
JB PH3,UP3
SETB OFFRLY
SETB MOT ;set motor bit
CLR LED3
CLR LD1
SETB MOTT
AJMP UP
HJ2: ; AUTO OFF
JNB AUTOOFF,$
CALL DELAY1
38
JNB AUTOOFF,$
JNB MOT, UP1
SETB NEW5
CLR LED2
CALL DELAY
AJMP SET_TIMER
UP1: AJMP UP
MOTOR_OFF:
JB LD1, UP1 ; chk motor status skip if motor is in off
SETB LED1
SETB LED2
SETB LED3
CLR MOT
CLR TR0
CLR TF0
CLR OFFRLY
SETB LD1
CLR NEW5
CLR NEW4
CLR MOTT
AJMP UP
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SET_TIMER:
SETB TIM1
39
SETB TIM2
SETB TIM3
SETB TIM4
SETB PH1
SETB PH2
SETB PH3
SETB AUTOOFF
JB TIM1,VB1
MOV OFF_TIME,#01H
CALL HALF_HR_DELAY
AJMP MOTOR_OFF
VB1: JB TIM2,VB2
MOV OFF_TIME,#02H
CALL HALF_HR_DELAY
CALL HALF_HR_DELAY
AJMP MOTOR_OFF
VB2: JB TIM3,VB3
MOV OFF_TIME,#03H
CALL HALF_HR_DELAY
CALL HALF_HR_DELAY
CALL HALF_HR_DELAY
AJMP MOTOR_OFF
VB3: JB TIM4, VB4
MOV OFF_TIME,#04H
40
CALL HALF_HR_DELAY
CALL HALF_HR_DELAY
CALL HALF_HR_DELAY
CALL HALF_HR_DELAY
AJMP MOTOR_OFF
VB4: AJMP UP
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
HALF_HR_DELAY:
MOV TMOD, #11H ; time delay for 1/2 hour
MOV R5, #30 ; count for 1/2 hour (30 for 1/2 Hour)
TP1: MOV R6,#60 ;count for 1 min (60 FOR 1 MIN)
TP: CPL LED2
MOV R7,#20
; Start timer for 1 SEC (20 for 1 Sec (50ms X 20=1 sec)
UP2: MOV TL0, #0AAH
MOV TH0, #3CH
SETB TR0
FGD: JNB AUTOOFF, DFS
JNB PH1, MOTOR_OFF1
JB PH2, MOTOR_OFF1
JB PH3, MOTOR_OFF1
JNB TF0, FGD
CLR TR0
41
CLR TF0
DJNZ R7, UP2
DJNZ R6, TP
DJNZ R5, TP1
RET
UPP: AJMP UP
MOTOR_OFF1:
JB LD1, UPP ; chk motor status skip if motor is in off
SETB LED3
SETB MOT
CLR OFFRLY
DFS: CLR TR0
CLR TF0
CLR MOTT
RET
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DELAY:
MOV R1, #0FFH
RE1: MOV R2, #0FFH
RE: NOP
DJNZ R2, RE
DJNZ R1, RE1
RET
42
;**********************************************************
DELAY1:
MOV R1, #9FH
REA1: MOV R2, #0FFH
REA: NOP
DJNZ R2, REA
DJNZ R1, REA1
RET
;**********************************************************
;##########################################################
; DISPLAY ROUTINES
;##########################################################
TITLES:
MOV DPTR,#MSAG
CALL LCD_MSG
RET
MSAG:
DB 1H, 81H,'3 Phase Motor', 0C0H,'Protection @ LCD', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TITLE1:
MOV DPTR,#MSAG1
CALL LCD_MSG
RET
MSAG1:
43
DB 1H, 81H,'## R Phase: ##', 0C1H,'Voltage Normal', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TITLE2:
MOV DPTR, #MSAG2
CALL LCD_MSG
RET
MSAG2:
DB 1H, 81H,'## Y Phase: ##', 0C1H,'Voltage Normal', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TITLE3:
MOV DPTR, #MSAG3
CALL LCD_MSG
RET
MSAG3:
DB 1H, 81H,'## B Phase: ##', 0C1H,'Voltage Normal', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TITLE11:
MOV DPTR,#MSAG4
CALL LCD_MSG
RET
MSAG4:
DB 1H, 81H,'## R Phase: ##', 0C0H,'Voltage ABNormal', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TITLE21:
MOV DPTR,#MSAG5
CALL LCD_MSG
44
RET
MSAG5:
DB 1H, 81H,'## Y Phase: ##', 0C0H,'Voltage ABNormal', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TITLE31:
MOV DPTR, #MSAG6
CALL LCD_MSG
RET
MSAG6:
DB 1H, 81H,'## B Phase: ##', 0C0H,'Voltage ABNormal', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
MOT_OFF:
MOV DPTR,#MSAG7
CALL LCD_MSG
RET
MSAG7:
DB 1H, 80H,'## MOTOR OFF ##',0C0H,'@@@@@@@@@@@@@@@@',00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
MOT_ON:
MOV DPTR,#MSAG8
CALL LCD_MSG
RET
MSAG8:
DB 1H,80H,'$$$ MOTOR ON $$$',0C0H,'@@@@@@@@@@@@@@@@',00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AUTO_OFF_ON:
45
MOV DPTR,#MSAG9
CALL LCD_MSG
RET
MSAG9:
DB 1H,81H,'## AUTO OFF ##',0C2H,'@@@ ON @@@',00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AUTO_OFF_OFF:
MOV DPTR,#MSAG10
CALL LCD_MSG
RET
MSAG10:
DB 1H,81H,'## AUTO OFF ##',0C2H,'@@@ OFF @@@',00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AUTO_ON_ON:
MOV DPTR,#MSAG11
CALL LCD_MSG
RET
MSAG11:
DB 1H,81H,'## AUTO ON ##',0C2H,'@@@ ON @@@',00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AUTO_ON_OFF:
MOV DPTR,#MSAG12
CALL LCD_MSG
RET
MSAG12:
DB 1H, 81H,'## AUTO ON ##', 0C2H,’@@@ OFF @@@’, 00H
46
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TIMER1:
MOV DPTR,#MSAG13
CALL LCD_MSG
RET
MSAG13:
DB 1H,80H,'OFF Timer: 30Min',00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TIMER2:
MOV DPTR,#MSAG14
CALL LCD_MSG
RET
MSAG14:
DB 1H, 80H,'OFF Timer: 1Hr', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TIMER3:
MOV DPTR,#MSAG15
CALL LCD_MSG
RET
MSAG15:
DB 1H, 80H,'OFF Timer: 1:30', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TIMER4:
MOV DPTR,#MSAG16
CALL LCD_MSG
RET
47
MSAG16:
DB 1H, 80H,'OFF Timer: 2:00', 00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
TIMER5:
MOV DPTR,#MSAG17
CALL LCD_MSG
RET
MSAG17:
DB 0C2H,’Time: ‘00H
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
;**********************************************************
; INITIALIZE THE LCD 4-BIT MODE
;**********************************************************
INITLCD4:
CLR LCD_RS ; LCD REGISTER SELECT LINE
CLR LCD_E ; ENABLE LINE
MOV R4, #CONFIG; FUNCTION SET - DATA BITS,
; LINES, FONTS
CALL WRLCDCOM4
MOV R4, #ONDSP; DISPLAY ON
CALL WRLCDCOM4
MOV R4, #ENTRYMODE; SET ENTRY MODE
CALL WRLCDCOM4; INCREMENT CURSOR RIGHT, NO SHIFT
MOV R4, #CLRDSP; CLEAR DISPLAY, HOME CURSOR
CALL WRLCDCOM4
RET
48
; **********************************************************
; SOFTWARE VERSION OF THE POWER ON RESET
; **********************************************************
RESETLCD4:
CLR LCD_RS ; LCD REGISTER SELECT LINE
CLR LCD_E ; ENABLE LINE
CLR LCD_DB7 ; SET BIT PATTERN FOR...
CLR LCD_DB6 ; ... POWER-ON-RESET
SETB LCD_DB5
SETB LCD_DB4
SETB LCD_E ; START ENABLE PULSE
CLR LCD_E ; END ENABLE PULSE
MOV A, #4 ; DELAY 4 MILLISECONDS
CALL MDELAY
SETB LCD_E ; START ENABLE PULSE
CLR LCD_E ; END ENABLE PULSE
MOV A, #1 ; DELAY 1 MILLISECOND
CALL MDELAY
SETB LCD_E ; START ENABLE PULSE
CLR LCD_E ; END ENABLE PULSE
MOV A, #1 ; DELAY 1 MILLISECOND
CALL MDELAY
CLR LCD_DB4 ; SPECIFY 4-BIT OPERATION
SETB LCD_E ; START ENABLE PULSE
CLR LCD_E ; END ENABLE PULSE
49
MOV A, #1 ; DELAY 1 MILLISECOND
CALL MDELAY
MOV R4, #CONFIG; FUNCTION SET
CALL WRLCDCOM4
MOV R4, #08H ; DISPLAY OFF
CALL WRLCDCOM4
MOV R4, #1 ; CLEAR DISPLAY, HOME CURSOR
CALL WRLCDCOM4
MOV R4,#ENTRYMODE ; SET ENTRY MODE
ACALL WRLCDCOM4
JMP INITLCD4
; **********************************************************
; SUB WRITES A COMMAND WORD TO THE LCD
; COMMAND MUST BE PLACED IN R4 BY CALLING PROGRAM
; **********************************************************
WRLCDCOM4:
CLR LCD_E
CLR LCD_RS ; SELECT SEND COMMAND
PUSH ACC ; SAVE ACCUMULATOR
MOV A, R4 ; PUT DATA BYTE IN ACC
MOV C, ACC.4 ; LOAD HIGH NIBBLE ON DATA BUS
MOV LCD_DB4, C ; ONE BIT AT A TIME USING...
MOV C, ACC.5 ; BIT MOVE OPERATOINS
MOV LCD_DB5, C
MOV C, ACC.6
50
MOV LCD_DB6, C
MOV C, ACC.7
MOV LCD_DB7, C
SETB LCD_E ; PULSE THE ENABLE LINE
CLR LCD_E
MOV C, ACC.0 ; SIMILARLY, LOAD LOW NIBBLE
MOV LCD_DB4, C
MOV C, ACC.1
MOV LCD_DB5, C
MOV C, ACC.2
MOV LCD_DB6, C
MOV C, ACC.3
MOV LCD_DB7, C
CLR LCD_E
SETB LCD_E ; PULSE THE ENABLE LINE
CLR LCD_E
CALL MADELAY
POP ACC
RET
; **********************************************************
; SUB TO WRITE A DATA WORD TO THE LCD
; DATA MUST BE PLACED IN R4 BY CALLING PROGRAM
; **********************************************************
WRLCDDATA:
CLR LCD_E
SETB LCD_RS ; SELECT SEND DATA
51
PUSH ACC ; SAVE ACCUMULATOR
MOV A, R4 ; PUT DATA BYTE IN ACC
MOV C, ACC.4 ; LOAD HIGH NIBBLE ON DATA BUS
MOV LCD_DB4, C ; ONE BIT AT A TIME USING...
MOV C, ACC.5 ; BIT MOVE OPERATOINS
MOV LCD_DB5, C
MOV C, ACC.6
MOV LCD_DB6, C
MOV C, ACC.7
MOV LCD_DB7, C
SETB LCD_E ; PULSE THE ENABLE LINE
CLR LCD_E
MOV C, ACC.0 ; SIMILARLY, LOAD LOW NIBBLE
MOV LCD_DB4, C
MOV C, ACC.1
MOV LCD_DB5, C
MOV C, ACC.2
MOV LCD_DB6, C
MOV C, ACC.3
MOV LCD_DB7, C
CLR LCD_E
SETB LCD_E ; PULSE THE ENABLE LINE
CLR LCD_E
NOP
NOP
POP ACC
52
RET
; **********************************************************
; SUB TAKES THE STRING IMMEDIATELY FOLLOWING THE CALL AND
; DISPLAYS ON THE LCD. STRING MUST BE TERMINATED WITH A
; NULL (0).
; **********************************************************
LCD_MSG:
CLR A ; Clear Index
MOVC A,@A+DPTR ; Get byte pointed by Dptr
INC DPTR ; Point to the next byte
JZ LCD_Msg9 ; Return if found the zero (end of strings)
CJNE A,#001H,Lcd_Msg1 ; Check if is a Clear Command
MOV R4, A
CALL WRLCDCOM4 ; If yes, write it as command to LCD
JMP LCD_MSG ; Go get next byte from strings
Lcd_Msg1: CJNE A, #0FFH, FLL ; Check for displaying full character
MOV R4, A
CALL WRLCDDATA
JMP LCD_MSG
FLL: CJNE A, #080h,$+3 ; Data or Address? If => 80h then is address.
JC Lcd_Msg_Data ; Carry will be set if A < 80h (Data)
MOV R4, A
CALL WRLCDCOM4 ; Carry not set if A=>80, it is address
JMP Lcd_Msg_Data ; Go get next byte from strings
53
Lcd_Msg_Data:
MOV R4, A
CALL WRLCDDATA ; It was data, write it to LCDs
JMP Lcd_Msg ; Go get next byte from strings
Lcd_Msg9:
RET ; Return to Caller
; **********************************************************
; 1 MILLISECOND DELAY ROUTINE
; **********************************************************
MDELAY:
PUSH ACC
MOV A,#0A6H
MD_OLP:
INC A
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
JNZ MD_OLP
NOP
54
POP ACC
RET
MADELAY:
PUSH ACC
MOV A,#036H
MAD_OLP:
INC A
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
JNZ MAD_OLP
NOP
POP ACC
RET
;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SCROLL:
DJNZ TIM, GAHJ1
CLR TR1
INC SCRL
DCDF: MOV A, SCRL
CJNE A,#01H,DFV1
55
JB NEW1, DFF1 ; CHK R VOL
CALL TITLE1
AJMP GAG
GAHJ1: AJMP GAHJ
DFF1: CALL TITLE11
AJMP GAG
DFV1: CJNE A,#02H,DFV2
JB NEW2, DFF2 ; CHK Y VOL
CALL TITLE2
AJMP GAG
DFF2: CALL TITLE21
AJMP GAG
DFV2: CJNE A,#03H,DFV3
JB NEW3,DFF3 ;CHK B VOL
CALL TITLE3
AJMP GAG
DFF3: CALL TITLE31
AJMP GAG
DFV3: CJNE A,#04H,DFV4 ;MOTOR NO/OFF
JB MOTT,DFF4
CALL MOT_OFF
AJMP GAG
DFF4: CALL MOT_ON
AJMP GAG
56
DFV4: CJNE A, #05H, DFV5 ; AUTO ON
JNB NEW4, DFF5
CALL AUTO_ON_ON
AJMP GAG
DFF5: CALL AUTO_ON_OFF
AJMP GAG
DFV5: CJNE A,#06H,DFV6 ;AUTO OFF
JNB NEW5, DFF6
CALL AUTO_OFF_ON
AJMP GAG
DFF6: CALL AUTO_OFF_OFF
AJMP GAG
DFV6: MOV SCRL, #00H
GAG: MOV TIM, #75
GAHJ: MOV TL1, #08H
MOV TH1, #01H
SETB TR1
RETI
DISP: SETB PH1
57
SETB PH2
SETB PH3
JNB PH1, DRE1
CLR NEW1
AJMP DEE1
DRE1: SETB NEW1
DEE1: JB PH2, DRE2
CLR NEW2
AJMP DEE2
DRE2: SETB NEW2
DEE2: JB PH3, DRE3
CLR NEW3
RET
DRE3: SETB NEW3
RET
END
4.10. CONCLUSION
Fault detection circuit is used for detection of the over and under voltages. From
the fault detection circuit output is given to microcontroller, by the program stored in the
microcontroller it activates the ON relay or OFF relay. The output of the microcontroller
is applied to the relays to switch ON and OFF the motor.
58
59
CHAPTER 5
EXPERMENTAL RESULTS AND CONCLUSION
5.1RESULT
This project concerns with experimental studies on the protection of induction
motor form over and under voltage and single phasing.
The experimental is conducted by connecting wires form experimental kit to
starter of the motor .our end result is the effective and reliable protection of three phase
induction motor from the faults of unbalanced supply voltages and single phasing.
5.2 CONCLUSION
In this project we are using LM 393 dual comparator to compare over/under
voltage.
Addition to this we are using two switches one for auto on and another for auto
off. Here the motor will run automatically when auto on is set and it will stop the motor
automatically after a particular time if auto off is set.
According to the program written in to the microcontroller the circuit will
automatically ON/OFF the motor .The prime use of the microcontroller is to protect the
motor from over and under voltages and to start and stop the motor automatically.
Microcontroller sends the signal to relays which is connected to the starter of
motor. According to the signal from controller the relay will start /stop the motor.
We have successfully completed the code required for the protection of the three
phase induction motor from the faults of unbalanced supply voltages and signal phasing.
The circuit is fabricated, the code is copied in to the microcontroller and we got
the desired results.
60
5.3 APPLICATION
This project can be used in any type of three phase motors, and the motor with any rating
can be easily adopted by just connecting the relay connections to the starter of the motor.
Agricultural motors
Industrial motors
5.4. FUTURE ENHANCEMENTS
A real time clock can be added so that the ON time and the OFF time of
the motor can be entered and the system will switch ON the motor and it
will switch OFF at the predetermined time.
An electronic lock can be provided so that unauthorized persons can‘t use
the motor.
Higher application.
Wireless implementation by FM/RF.
This project can be extend to protect the induction motor form phasor
faults and phase reversal.
61
BIBLIOGRAPHY:
1. P.S Bimbhra, Electric Machinery, Khanna Publishers, Edition Seventh 2004
August
2. Samsung, E-book -Networking and Internetworking with Microcontrollers
3. www.8051projects.info
4. www.lmphotonics.com
5. www.taylorandfrancis.com
6. www.metapress.com_protection techniques
7. www.ia.omron.com_relays
62
Appendix 1
LM7805 Regulator
LM78LXX SERIES
3-TERMINAL POSITIVE REGULATORS
GENERAL DESCRIPTION
The LM78LXX series of three terminal positive regulators is available with several fixed
output voltages making them useful in a wide range of applications. When used as a
zener diode/resistor combination replacement, the LM78LXX usually results in an
effective output impedance improvement of two orders of magnitude, and lower
quiescent current. These regulators can provide local on card regulation, eliminating the
distribution problems associated with single point regulation. The voltages available
allow the LM78LXX to be used in logic systems, instrumentation, HiFi, and other solid
state electronic equipment.
The LM78LXX is available in the plastic TO-92 (Z) package, the plastic SO-8 (M)
package and a chip sized package (8-Bump micro SMD) using National’s micro SMD
package technology. With adequate heat sinking the regulator can deliver 100mA output
current. Current limiting is included to limit the peak output current to a safe value. Safe
area protection for the output transistors is provided to limit internal power dissipation. If
internal power dissipation becomes too high for the heat sinking provided, the thermal
shutdown circuit takes over preventing the IC from overheating.
Features
LM78L05 in micro SMD package
Output voltage tolerances of ±5% over the temperature range
Output current of 100mA
Internal thermal overload protection n Output transistor safe area
protection n Internal short circuit current limit
Available in plastic TO-92 and plastic SO-8 low profile packages
No external components
Output voltages of 5.0V, 6.2V, 8.2V, 9.0V, 12V, 15V n See AN-1112 for
micro SMD considerations
63
CONNECTION DIAGRAMS
SO-8 Plastic (M) (TO-92)
(Narrow Body)Plastic
Package (Z)
Bottom View
Top View
Micro SMD Marking Orientation
8-Bump micro SMD
00774424
Top View(Bump Side Down)
00774433
Top View
64
Typical Performance Characteristics
Maximum Average Power Dissipation (Z Package) Peak Output Current
00774414 00774416
Dropout Voltage Ripple Rejection
00774417
00774418
Output Impedance Quiescent Current
65
TYPICAL APPLICATIONS
Fixed Output Regulator
00774408*Required if the regulator is located more than 3" from the power supply filter.
**See (Note 4) in the electrical characteristics table.
Adjustable Output Regulator
00774409
VOUT = 5V + (5V/R1 + IQ) R2
3 IQ, load regulation (Lr) ≈ [(R1 + R2)/R1] (Lr of LM78L05)
Current Regulator
00774410
IOUT = (VOUT/R1) + IQ
>IQ = 1.5mA over line and load changes
5V, 500mA Regulator with Short Circuit Protection
00774411
66
*Solid tantalum. **Heat sink Q1. ***Optional: Improves ripple rejection and transient response. Load Regulation: 0.6% 0 ≤ IL ≤ 250mA pulsed with
tON = 50ms
±15V, 100mA Dual Power Supply
Variable Output Regulator 0.5V-18V
Solid tatalum
VOUT = VG + 5V, R1 = (−VIN/IQ LM78L05)
VOUT = 5V (R2/R4) for (R2 + R3) = (R4 + R5)
A 0.5V output will correspond to (R2/R4) = 0.1(R3/R4) = 0.9
67
Appendix 2THEORY OF MICROCONTROLLER
FEATURES Compatible with MCS®-51 Products 8K Bytes of In-System Programmable (ISP) Flash
Memory –Endurance: 10,000 Write/Erase Cycles 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz Three-level Program Memory Lock 256 x 8-bit Internal RAM 32 Programmable I/O Lines Three 16-bit Timer/Counters Eight Interrupt Sources Full Duplex UART Serial Channel Low-power Idle and Power-down Modes Interrupt Recovery from Power-down Mode Watchdog Timer Dual Data Pointer Power-off Flag Fast Programming Time Flexible ISP Programming (Byte and Page Mode) Green (Pb/Halide-free) Packaging Option
1. DESCRIPTION
The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the indus-try-standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory pro-grammer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications.
The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 is designed with static logic for operation 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 con-tents but freezes the oscillator, disabling all other chip functions until the next interrupt or
68
hardware reset.
AUXR: Auxiliary Register
AUXR Address = 8EH
Reset Value = XXX00XX0B
Not Bit Addressable
– -- – WDIDLE DISRTO – –
DISALE
Bit 7 6 5 4 3 2 1 0
–Reserved for future expansion
DISALE
Disable/Enable ALEDISALE
Operating Mode
0 ALE is emitted at a constant rate of 1/6 the oscillator frequency
1 ALE is active only during a MOVX or MOVC instruction
DISRTO Disable/Enable Reset out
DISRTO
0 Reset pin is driven High after WDT times out
1 Reset pin is input only
WDIDLE Disable/Enable WDT in IDLE mode
WDIDLE
0 WDT continues to count in IDLE mode
1 WDT halts counting in IDLE mode
Dual Data Pointer Registers: To facilitate accessing both internal and external data memory, two banks of 16-bit Data Pointer Registers are provided: DP0 at SFR address locations 82H-83H and DP1 at 84H-85H. Bit DPS = 0 in SFR AUXR1 selects DP0 and DPS = 1 selects DP1. The user should ALWAYS initialize the DPS bit to the appropriate value before accessing the respective Data Pointer Register.
Power off Flag: The Power Off Flag (POF) is located at bit 4 (PCON.4) in the PCON SFR. POF is set to “1” during power up. It can be set and rest under software control and
69
is not affected by reset
AUXR1: Auxiliary Register 1
AUXR1
Address = A2H
Reset Value = XXXXXXX0B
Not Bit Addressable
-- -- -- -- -- -- -- DPS
Bit 7 6 5 4 3 2 1 0
–Reserved for future expansion
DPSData Pointer Register Select
DPS
0 Selects DPTR Registers DP0L, DP0H
1 Selects DPTR Registers DP1L, DP1H
70
T2MOD – Timer 2 Mode Control Register
T2MOD Address = 0C9H Reset Value = XXXX XX00BNot Bit Addressable
– – – – – – T2OE DCEN
Bit 7 6 5 4 3 2 1 0
SymbolFunction
–Not implemented, reserved for future
T2OE Timer 2 Output Enable bit
DCEN When set, this bit allows Timer 2 to be configured as an up/down counter
Figure 1 shows Timer 2 automatically counting up when DCEN = 0. In this mode, two
options are selected by bit EXEN2 in T2CON. If EXEN2 = 0, Timer 2 counts up to
0FFFFH and then sets the TF2 bit upon overflow. The overflow also causes the timer
registers to be reloaded with the 16-bit value in RCAP2H and RCAP2L. The values in
Timer in Capture ModeRCAP2H and RCAP2L are preset by software. If EXEN2 = 1, a
16-bit reload can be triggered either by an overflow or by a 1-to-0 transition at external
71
input T2EX. This transition also sets the EXF2 bit. Both the TF2 and EXF2 bits can
generate an interrupt if enabled. Setting the DCEN bit enables Timer 2 to count up or
down, as shown in Figure 10-2. In this mode, the T2EX pin controls the direction of the
count. Logic 1 at T2EX makes Timer 2 count up. The timer will overflow at 0FFFFH and
set the TF2 bit. This overflow also causes the 16-bit value in RCAP2H and RCAP2L
to be reloaded into the timer registers, TH2 and TL2,respectively.
Logic 0 at T2EX makes Timer 2 count down. The timer underflows when
TH2 and TL2 equal the values stored in RCAP2H and RCAP2L. The underflow sets the
TF2 bit and causes 0FFFFH to be reloaded into the timer registers.
The EXF2 bit toggles whenever Timer 2 overflows or underflows and can be used as a
17th bit of resolution. In this operating mode, EXF2 does not flag an interrupt.
Table 2 Interrupt Enable (IE) Register
(MSB) (LSB)
EA – ET2 ES ET1 EX1 ET0 EX0
Enable Bit = 1 enables the interrupt.
Enable Bit = 0 disables the interrupt.
Symbol Position Function
EA IE.7
Disables all interrupts. If EA = 0, no interrupt is acknowledged. If EA = 1, eachinterrupt source is individually enabled or disabled by setting or clearing its enable bit.
– IE.6 Reserved.
ET2 IE.5 Timer 2 interrupt enable bit.
ES IE.4 Serial Port interrupt enable bit.
ET1 IE.3 Timer 1 interrupt enable bit.
72
EX1 IE.2 External interrupt 1 enable bit.
ET0IE.1 Timer 0 interrupt enable bit.
EX0 IE.0 External interrupt 0 enable bit.
User software should never write 1s to reserved bits, because they may be used in future AT89 products.
Figure 13 .1.Interrupt Sources
0
1
TF0
0
INT1
1
TF1
73
INT1
IE0
IE0
T1
R1
TF2
EXF2
Table 3. Serial Programming Instruction Set
Instruction
Format
Instruction Byte 1 Byte 2 Byte 3 Byte 4 Operation
1010 1100 0101 0011 xxxx xxxx xxxxxxxx
Programming Enable
0110 1001Enable Serial Programming
(Output on while RST is high
MISO)
Chip Erase1010 1100 100x xxxx xxxx xxxx xxxx
xxxx Chip Erase Flash memory
array
Read Program Memory 0010 0000 xxx
A12 A1
1A10
A9A8 Read data from Program
(Byte Mode) memory in the byte mode
Write Program Memory 0100 0000 xxx
A12 A1
1A10
A9A8
A 7 A 6A 3 A 2 D 7
D5D4
D3
D2
D1
D0
Write data to Program
(Byte Mode) memory in the byte mode
Write Lock
Bits (1 ) 1010 1100 1110 00B1B2 xxxx xxxx xxxxxxxx
Write Lock bits. See Note (1).
0010 0100 xxxx xxxx xxxx xxxxxxx
LB
3 LB2L
B1xx Read back current status ofRead Lock Bits
the lock bits (a programmedlock bit reads back as a “1”)
Read Signature Bytes
0010 1000 xxx
A12 A1
1A10
A9A8
A7xxx xxx0 Signature Byte Read Signature Byte
74
Read Program Memory 0011 0000 xxx
A12 A1
1A10
A9A8 Byte 0 Byte 1... Read data from Program
Byte 255 memory in the Page Mode(Page Mode)
(256 bytes)
Write Program Memory
0101 0000 xxx
A12 A1
1A10 A9
A8 Byte 0 Byte 1... Write data to Program
Byte 255 memory in the Page Mode(Page Mode)
(256 bytes)
After Reset signal is high, SCK should be low for at least 64 system clocks before it goes high to clock in the enable data bytes. No pulsing of Reset signal is necessary. SCK should be no faster than 1/16 of the system clock at XTAL1.
For Page Read/Write, the data always starts from byte 0 to 255. After the command byte and upper address byte are latched, each byte thereafter is treated as data until all 256 bytes are shifted in/out. Then the next instruction will be ready to be decoded.
28. AC CharacteristicsUnder operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all other outputs = 80 pF.
28.1 External Program and Data Memory CharacteristicsSymbol Parameter Min Max Min Max Units
1/tCLCL Oscillator Frequency 0 33 MHztLHLL ALE Pulse Width 127 2tCLCL-40 nstAVLL Address Valid to ALE Low 43 tCLCL-25 nstLLAX Address Hold After ALE Low 48 tCLCL-25 nstLLIV ALE Low to Valid Instruction In 233 4tCLCL-65 nstLLPL ALE Low to PSEN Low 43 tCLCL-25 nstPLPH PSEN Pulse Width 205 3tCLCL-45 nstPLIV PSEN Low to Valid Instruction In 145 3tCLCL-60 nstPXIX Input Instruction Hold After PSEN 0 0 nstPXIZ Input Instruction Float After PSEN 59 tCLCL-25 ns
75
tPXAV PSEN to Address Valid 75 tCLCL-8 nstAVIV Address to Valid Instruction In 312 5tCLCL-80 nstPLAZ PSEN Low to Address Float 10 10 nstRLRH RD Pulse Width 400 6tCLCL-100 nstWLW
H WR Pulse Width 400 6tCLCL-100 nstRLDV RD Low to Valid Data In 252 5tCLCL-90 nstRHDX Data Hold After RD 0 0 nstRHDZ Data Float After RD 97 2tCLCL-28 nstLLDV ALE Low to Valid Data In 517 8tCLCL-150 nstAVDV Address to Valid Data In 585 9tCLCL-165 nstLLWL ALE Low to RD or WR Low 200 300 3tCLCL-50 3tCLCL+50 nstAVWL Address to RD or WR Low 203 4tCLCL-75 ns
tQVWX Data Valid to WR Transition 23 tCLCL-30 ns
tQVWH Data Valid to WR High 433 7tCLCL-130 ns
tWHQX Data Hold After WR 33 tCLCL-25 ns
tRLAZ
tWHLH RD or WR High to ALE High 43 123 tCLCL-25 tCLCL+25 ns
76
RD Low to Address Float 0 0 ns
Appendix 3LM193/LM293/LM393/LM2903
Low Power Low Offset Voltage Dual Comparators
General Description
The LM193 series consists of two independent precision voltage comparators with an
offset voltage specification as low as 2.0 mV max for two comparators which were
designed specifically to operate from a single power supply over a wide range of
voltages. Operation from split power supplies is also possible and the low power supply
current drain is independent of the magnitude of the power supplyvoltage. These
comparators also have a unique characteristic in that the input common-mode voltage
range includes ground, even though operated from a single power supplyvoltage.
Application areas include limit comparators, simple analog to digital converters; pulse,
squarewave and time delay generators; wide range VCO; MOS clock timers;
multivibrators and high voltage digital logic gates. The LM193 series was designed to
directly interface with TTL and CMOS. When operated from both plus and minus power
supplies, the LM193 series will directly interface with MOS logic where their low power
drain is a distinct advantage over standard comparators. The LM393 and LM2903 parts
are available in National’s innovative thin micro SMD package with 8 (12 mil) large
bumps.
Advantages
High precision comparators
Reduced VOS drift over temperature
Eliminates need for dual supplies
Allows sensing near ground
Compatible with all forms of logic
Power drain suitable for battery operation
77
Features Wide supply
Voltage range: 2.0V to 36V
Single or dual supplies: ±1.0V to ±18V
Very low supply current drain (0.4 mA) — independent
of supply voltage
Low input biasing current: 25 nA
Low input offset current: ±5 nA
Maximum offset voltage: ±3 mV
Input common-mode voltage range includes ground
Differential input voltage range equal to the power
supply voltage
Low output saturation voltage,: 250 mV at 4 mA
Output voltage compatible with TTL, DTL, ECL, MOS
and CMOS logic systems
Available in the 8-Bump (12 mil) micro SMD package
See AN-1112 for micro SMD considerations
Squarewave Oscillator Non-Inverting Comparator with Hysteresis
78
79
00570902
MetalDual-In-Line/SOIC Package
Schematic and Connection Diagram
s
Metal Can Package Dual-In-Line/SOIC Package
micro SMD Marking
80
Miro SMD
Micro SMD Maring
Top View Top View
81
Typical Performance Characteristics
Application Hints
The LM193 series are high gain, wide bandwidth devices which, like most
comparators, can easily oscillate if the output lead is inadvertently allowed to capacitively
couple to the inputs via stray capacitance. This shows up only during the output voltage
transition intervals as the comparator change states. Power supply bypassing is not
required to solve this problem. Standard PC board layout is helpful as it reduces stray
input-output coupling. Reducing the input re-sistors to < 10 kΩ reduces the feedback
signal levels and finally, adding even a small amount (1.0 to 10 mV) of positive feedback
(hysteresis) causes such a rapid transition that oscillations due to stray feedback are not
possible. Simply socketing the IC and attaching resistors to the pins will cause input-
output oscillations during the small transition intervals unless hysteresis is used. If the
input signal is a pulse waveform, with relatively fast rise and fall times, hysteresis is not
required.
All input pins of any unused comparators should be tied to the negative supply.
The bias network of the LM193 series establishes a drain current which is independent of
the magnitude of the power supply voltage over the range of from 2.0 VDC to 30 VDC.
It is usually unnecessary to use a bypass capacitor across the power supply line.
The differential input voltage may be larger than V+ without damaging the device (Note
8). Protection should be provided to prevent the input voltages from going negative more
than −0.3 VDC (at 25˚C). An input clamp diode can be used as shown in the applications
section.
The output of the LM193 series is the uncommitted collector of a grounded-emitter NPN
output transistor. Many collectors can be tied together to provide an output OR’ing
function. An output pull-up resistor can be connected to any available power supply
voltage within the permitted supply voltage range and there is no restriction on this
voltage due to the magnitude of the voltage which is applied to the V+ terminal of the
LM193 package. The output can also be used as a simple SPST switch to ground (when a
pull-up resistor is not used). The amount of current which the output device can sink is
limited by the drive available (which is independent of V+) and the β of this device. When
the maximum current limit is reached (approximately 16mA), the output transistor will
come out of saturation and the output voltage will rise very rapidly. The output saturation
voltage is limited by the ap-proximately 60Ω rSAT of the output transistor. The low offset
voltage of the output transistor (1.0mV) allows the output to clamp essentially to ground
82
level for small load currents.
Typical Applications (V+=5.0 VDC)
Basic Comparator Non-Inverting Comparator with Hysteresis
83
Squarewave Oscillator
Pulse Generator Crystal Controlled Oscillator
Typical Applications (V+=5.0 VDC) (Continued)
Inverting Comparator with Hysteresis Output Strobing
AND Gate OR Gate
Large Fan-in AND Gate Limit Comparator
84
Typical Applications (V+=5.0 VDC) (Continued)
Comparing Input Voltages of Opposite Polarity ORing the Outputs
Zero Crossing Detector (Single Power Supply)
One-Shot Multivibrator
Bi-Stable Multivibrator One-Shot Multivibrator with Input Lock Out
Zero Crossing DetectorComparator With a Negative Reference
85
Typical Applications (V+=5.0 VDC) (Continued)
Time Delay Generator
Split-Supply Applications (V+=+15 VDC and V−=−15 VDC)
MOS Clock Driver
86