INTRODUCTION Radar is an Electromagnetic system which uses radio waves to detect the existence of an object and then to find its position in rotation to a known point. By means of radar the presence of moving or stationary objects such as aircrafts, ships and land masses can be detected. In addition, information concerning the exact position of the object (usually referred to as a target) and its speed and direction, where applicable can be obtained. The word RADAR is coined from the initial letters of the phrase: ‘Radar Detection and Ranging’. Although radar was originally introduced to give warning of the approach of hostile aircraft it has since been further developed to do much more than its original task. Modern radar equipment plays a vital part in all the operational roles of the RAF(Rapid Action Force) as an aid to accurate bombing; in airborne detection and interception equipment; for the control of guided weapons, as navigational and landing aids, in cloud and collision warning devices. It has many other uses in the civilian as well as in the service field. Most radar equipment are pulse-modulated, i.e. the radiation from the transmitter aerial is in the form of very short bursts or pulses of radio frequency energy, each pulse being followed by a relatively long resting period during - 1 -
Transcript
INTRODUCTION
Radar is an Electromagnetic system which uses radio waves to detect the
existence of an object and then to find its position in rotation to a known point. By means
of radar the presence of moving or stationary objects such as aircrafts, ships and land
masses can be detected. In addition, information concerning the exact position of the
object (usually referred to as a target) and its speed and direction, where applicable can
be obtained. The word RADAR is coined from the initial letters of the phrase: ‘Radar
Detection and Ranging’.
Although radar was originally introduced to give warning of the approach of
hostile aircraft it has since been further developed to do much more than its original task.
Modern radar equipment plays a vital part in all the operational roles of the RAF(Rapid
Action Force) as an aid to accurate bombing; in airborne detection and interception
equipment; for the control of guided weapons, as navigational and landing aids, in cloud
and collision warning devices. It has many other uses in the civilian as well as in the
service field.
Most radar equipment are pulse-modulated, i.e. the radiation from the
transmitter aerial is in the form of very short bursts or pulses of radio frequency energy,
each pulse being followed by a relatively long resting period during which the transmitter
is switched off and the receiver is operating. For certain applications pulse-modulated
radar has limitations. A form of continuous wave is then used. This may be:
(a) Pulse continuous wave radar relying on the ‘Doppler shift’ in frequency to detect
moving objects and to measure their speed.
(b) Frequency-modulated continuous wave radar where the difference between the
reflected wave from a target and the direct waveform transmitter to receiver gives
an indication of the range of the target
Ground Controlled Interception (GCI)
Without the assistance of ground based primary radar installations, even well
equipped, high performance interceptor (fighter) aircraft and surface to air missile (SAM)
would be useless. It is only on the information supplied by the ground radar that defenses
can be activated and properly controlled.
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From the above discussion we can see that the pulses of RF energy radiated by a
radar transmitter may be reflected from aircraft. The resulting echoes can be used to
detect and to find the range bearing and height of enemy aircraft so that fighters or
missiles can be guided to an interception position in the sky.
In our Project, an IR transmitter and receiver are being used instead of RF
transmitter and receiver which are placed on an antenna which is rotated by a stepper
motor to detect angle of the object. Also, we are simulating the RADAR function with
optical beam. The RADAR senses a flight passing around and a gun that can be rotated
by means of a stepper motor is placed along with it. the gun aims at that particular flight
and blasts it. This happens even when the flights passing by are not able to produce the
codes. This scanning process can be viewed in the PC. RS232 cable is used for the
communication between PC and the Micro Controller. A Micro Controller is used to
supervise the above functions according to the program stored in it. This program is made
in assembly language. At the receiving end, for the computer, the program is written in
‘C’ language to receive the serial data from the Micro Controller and to display the object
information on the monitor. Therefore, this module finds its application mostly in
Defense for the purpose of security.
Therefore, this module finds its application mostly in Defense for the purpose of
security.
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BLOCK DIAGRAM
2.1 Block Diagram
Fig2.1 Block diagram of Transmitter section
TX Antenna
Fig 2.2 Block diagram of control Section
From FM RX
+12V
+5V
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FM Transmitter
2051MCCode generator
Power supply
PC RS 232
8051 Micro controller
Motor1 Driver
Motor 2 Driver
Motor1
Motor 2
Gun Led
Antenna
IR Receiver
Firing indicator
Voltage regulatorPower supply
Fig 2.3Block diagram of Receiver section
RX Antenna
2051
FM RX Micro To control section
Controller
Amplifier Unit
2.2 Description
The antenna connected to stepper motor. When power is switched on, antenna a
will move to their home positions. Then it searches communication link from PC. If
commands are Coming, it moves the antenna. If CW command received, it moves in
clockwise direction. If CCW command received, it moves in counter clockwise direction.
When a target (i.e.) a flight in the space is being intersected with the rays emitted by the
antenna, part of these rays are reflected back. This echo signal is collected or received by
the IR receiver, which gives an interrupt to 89C51 micro controller For every step, it
reads the IR receiver feedback . If obstacle is present then it sends signal to pc
On receiving these signals, PC will indicate with red signal. A full duplex
communication is established between PC and micro controller. For every step, PC sends
movement command to MC and MC sends back obstacle feed back to PC. If no obstacle
detected, MC will send no obstacle feedback and PC will not mark any thing.
PC Block
The PC is having various I/O peripherals such as parallel port, serial (COM) port,
USB port, modems etc. For our project we have taken serial (COM) port because in
monoplex mode of communication, only one wire is sufficient. Here we can transmit
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single wire information, so we have chosen this port. A ninepin D – type connector is
placed at the rear panel of the PC through which we take data using an interfacing cable.
For taking commands and transmitting the data, ‘C’ language is used. An user friendly
menu is created for better operation
F.M. Transmitter
This block generates a continuous frequency of 100MHz, which is used to form a
permanent link between the transmitter and receiver, and this is known as carrier
frequency. The output serial port is fed to this F.M radio transmitter. This is a frequency
modulated radio transmitter. The radiating power of the transmitter is 20mw, and it is
designed using 2N3904 high frequency switching transistor.
IR transmitter:
This transmits IR rays into the space (in all directions) for sensing the presence of target.
IR receiver:
When a target is intersected by emitted rays of the IR transmitter (RADAR antenna), a
portion of intersected rays are re-emitted back which is collected by IR receiver. This
information is sent to micro controller 89C51.Thus ensuring the presence of target in
space.
Stepper motor driver:
IRF540 mosfets are used to drive the stepper motors.
Stepper motors:
Unipolar (Half step sequence) stepper motor are used for rotating antenna .
FM Receiver
The FM receiver is designed with IC CXA1619BM/BS, which is AM/FM Radio
receiver IC, operates at a local oscillator of 88 - 108MHz and is tuned with the transmitter.
This IC consists of built in RF amplifier, a double balanced mixer, local oscillator, a two
stage IF amplifier, a quadrature demodulator for a ceramic filter and an automatic
frequency control. The built in RF amplifier, a part from the amplification of received RF
signal, it also reduces the Noise figure, which could other wise be a problem because of the
large band widths needed for FM. It also matches the input impedance of the radio receiver
with the antenna.
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8 bit micro controller
The Micro controller is used for interface with FM receiver and stepper motors and
it gives proper stepping pulses for vehicle movements, by receiving serial data from FM
receiver.
2.3 Conclusion
Here in this chapter total Block diagram blocks have clearly Descripted and also
according to the aim of the project we are using components and blocks are clearly
clarified So, we can easily know how the project will fabricate for that we go for next
step .
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MICROCONTROLLER
The Micro controller is used for interface with PC, stepper motors, IR receiver and
code comparator and it gives proper stepping pulses for RADAR and GUN movements,
by receiving serial data from PC.
3.1 Introduction
Looking back into the history of microcomputers, one would at first come across
the development of microprocessor i.e. the processing element, and later on the
peripheral devices. The three basic elements-the CPU, I/O devices and memory-have
developed in distinct directions. While the CPU has been the proprietary item, the
memory devices fall into general-purpose category and the I/O devices may be grouped
somewhere in-between.
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer
with 4K bytes of Flash programmable and erasable read only memory (PEROM). The
device is manufactured using Atmel’s high-density nonvolatile memory technology and
is compatible with the industry-standard MCS-51 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 AT89C51 is a powerful microcomputer, which provides a
highly flexible and cost-effective solution to many embedded control applications.
The AT89C51 provides for 4k EPROM/ROM, 128 byte RAM and 32 I/O lines. It
also includes a universal asynchronous receive-transmit (UART) device, two 16-bit
timer/counters and elaborate interrupt logic. Lack of multiply and divide instructions
which had been always felt in 8-bit microprocessors/micro controllers, has also been
taken care of in the 89C51- Thus the 89C51 may be called nearly equivalent of the
following devices on a single chip: 8085 + 8255 + 8251 + 8253 + 2764 + 6116.
In short, the AT89C51 has the following on-chip facilities:
4k ROM (EPROM on 8751)
128 byte RAM
UART
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32 input-output port lines
Two, 16-bit timer/counters
Six interrupt sources and
On-chip clock oscillator and power on reset circuitry
3.2 Internal Block diagram
Fig 3.1 – AT89C51 internal block diagram
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3.3 Silent features
The 89C51 can be configured to bypass, the internal 4k ROM and run solely with
external program memory. For this its external access (EA) pin has to be grounded,
which makes it equivalent to 8031. The program store enable (PSEN) signal acts as read
pulse for program memory. The data memory is external only and a separate RD* signal
is available for reading its contents.
Use of external memory requires that three of its 8-bit ports (out of four) are
configured to provide data/address multiplexed bus. Hi address bus and control signals
related to external memory use. The RXD and TXD ports of UART also appear on pins
10 and 11 of 8051 and 8031, respectively. One 8-bit port, which is bit addressable and,
extremely useful for control applications.
The UART utilizes one of the internal timers for generation of baud rate. The
crystal used for generation of CPU clock has therefore to be chosen carefully. The
11.0596 MHz crystals; available abundantly, can provide a baud rate of 9600.
The 256-byte address space is utilized by the internal RAM and special function
registers (SFRs) array which is separate from external data RAM space of 64k. The 00-
7F space is occupied by the RAM and the 80 - FF space by the SFRs. The 128 byte
internal RAM has been utilized in the following fashion:
00-IF: Used for four banks of eight registers of 8-bit each. The four banks may be
selected by software any time during the program.
20-2F: The 16 bytes may be used as 128 bits of individually addressable
locations. These are extremely useful for bit oriented programs.
30- 7F: This area is used for temporary storage, pointers and stack. On reset,
the stack starts at 08 and gets incremented during use.
The list of special function registers along with their hex addresses is given .
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Table 3.1 AT89C51 Address register
Addr. Port/Register
80 P0 (Port 0)
81 SP (stack pointer)
82 DPH (data pointer High)
83 DPL (data pointer Low)
88 TCON (timer control)
89 TMOD (timer mode)
8A TLO (timer 0 low byte)
8B TL1 (timer 1 low byte)
8C TH0 (timer 0 high byte)
8D TH1 (timer 1 high byte)
90 P1 (port 1)
98 SCON (serial control)
99 SBUF (serial buffer)
A0 P2 (port 2)
A8 Interrupt enable (IE)
B0 P3 (port 3)
B8 Interrupt priority (IP)
D0 Processor status word (PSW)
E0 Accumulator (ACC)
F0 B register
Table 3.1 – AT89C51 SFR
3.4 Hardware details
The on chip oscillator of 89C51 can be used to generate system clock. Depending
upon version of the device, crystals from 3.5 to 12 MHz may be used for this purpose.
The system clock is internally divided by 6 and the resultant time period becomes one
processor cycle. The instructions take mostly one or two processor cycles to execute, and
very occasionally three processor cycles. The ALE (address latch enable) pulse rate is
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16th of the system clock, except during access of internal program memory, and thus can
be used for timing purposes.
AT89C51 Serial port pins
PIN ALTERNATE USE SFR
P3.ORXD Serial data input SBUF
P3.ITXD Serial data output SBUF
P3.2INTO External interrupt 0 TCON-1
P3.3INT1 External interrupt 1 TCON- 2
P3.4TO External timer 0 input TMOD
P3.5T1 External timer 1 input TMOD
P3.6WR External memory write pulse ---------
P3.7RD External memory read pulse ----
Table 3.2 – AT89C51 serial port pins
The two internal timers are wired to the system clock and prescaling factor is
decided by the software, apart from the count stored in the two bytes of the timer control
registers. One of the counters, as mentioned earlier, is used for generation of baud rate
clock for the UART. It would be of interest to know that the 8052 have a third timer,
which is usually used for generation of baud rate.
The reset input is normally low and taking it high resets the micro controller, In the
present hardware, a separate CMOS circuit has been used for generation of reset signal so
that it could be used to drive external devices as well.
3.5 Writing the software
The 89C51 has been specifically developed for control applications. As
mentioned earlier, out of the 128 bytes of internal RAM, 16 bytes have been organized in
such a way that all the 128 bits associated with this group may be accessed bit wise to
facilitate their use for bit set/reset/test applications. These are therefore extremely useful
for programs involving individual logical operations. One can easily give example of lift
for one such application where each one of the floors, door condition, etc may be
depicted by a single hit.
The 89C51 has instructions for bit manipulation and testing. Apart from these, it
has 8-bit multiply and divide instructions, which may be used with advantage. The 89C51
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has short branch instructions for 'within page' and conditional jumps, short jumps and
calls within 2k memory space which are very convenient, and as such the controller
seems to favor programs which are less than 2k byte long. Some versions of 8751
EPROM devices have a security bit which can be programmed to lock the device and
then the contents of internal program EPROM cannot be read.
The device has to be erased in full for further alteration, and thus it can only be
reused but not copied. EEPROM and FLASH memory versions of the device are also
available now. The term used in micro controller is:
3.6 Memory unit
Memory is part of the micro controller whose function is to store data. The
easiest way to explain it is to describe it as one big closet with lots of drawers. If we
suppose that we marked the drawers in such a way that they cannot be confused, any of
their contents will then be easily accessible. It is enough to know the designation of the
drawer and so its contents will be known to us for sure.
Memory components are exactly like that. For a certain input we get the contents
of a certain addressed memory location and that’s all. Two new concepts are brought to
us: addressing and memory location. Memory consists of all memory locations, and
addressing is nothing but selecting one of them. This means that we need to select the
desired memory location on one hand, and on the other hand we need to wait for the
contents of that location. Besides reading from a memory location, memory must also
provide for writing onto it. This is done by supplying an additional line, called control
line. We will designate this line as R/W (read/write). Control line is used in the following
way: if r/w=1, reading is done, and if opposite is true then writing is done on the memory
location. Memory is the first element, and we need a few operation of our micro
controller.
3.7 Central Processing Unit
Let add 3 more memory locations to a specific block that will have a built in
capability to multiply, divide, subtract, and move its contents from one memory location
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onto another. The part we just added in is called “central processing unit” (CPU). Its
memory locations are called registers.
Registers are therefore memory locations whose role is to help with performing
various mathematical operations or any other operations with data wherever data can be
found. Look at the current situation. We have two independent entities (memory and
CPU), which are interconnected, and thus any exchange of data is hindered, as well as its
functionality. If, for example, we wish to add the contents of two memory locations and
return the result again back to memory, we would need a connection between memory
and CPU. Simply stated, we must have some “way” through data goes from one block to
another.
3.8 Bus
That “way” is called “bus”. Physically, it represents a group of 8, 16, or more
wires. There are two types of buses: address and data bus. The first one consists of as
many lines as the amount of memory we wish to address, and the other one is as wide as
data, in our case 8 bits or the connection line. First one serves to transmit address from
CPU memory, and the second to connect all blocks inside the micro controller.
3.9 Input-output unit
Those locations we’ve just added are called “ports”. There are several types of
ports: input, output or bi-directional ports. When working with ports, first of all it is
necessary to choose which port we need to work with, and then to send data to, or take it
from the port. When working with it the port acts like a memory location.
Something is simply being written into or read from it, and it could be noticed on the pins
of the micro-controller.
3.10 Conclusion
Here we explained about the microcontroller that is using in the project .the blocks of
microcontroller is briefly explained.
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RADAR
Although British physicist James Clerk Maxwell predicted the existence
of radio waves in the 1860s, it wasn’t until the 1890s that British-born American inventor
Elihu Thomson and German physicist Heinrich Hertz independently confirmed their
existence. Scientists soon realized that radio waves could bounce off of objects, and by
1904 Christian Hülsmeyer, a German inventor, had used radio waves in a collision
avoidance device for ships.Scientists at the U.S. Naval Research Laboratory in
Washington, D.C., became the first to use radar to detect aircraft in 1930.
Fig 4.1 radar block diagram
Radar (Radio detection and Ranging) is something that is in use all around us, although it
is normally invisible. Air traffic control uses radar to track planes both on the ground and
in the air, and also to guide planes in for smooth landings. Police use radar to detect the
speed of passing motorists. NASA uses radar to map the Earth and other planets, to track
satellites and space debris and to help with things like docking and maneuvering. The
military uses it to detect the enemy and to guide weapons. Meteorologists use radar to
track storms, hurricanes and tornadoes. You even see a form of radar at many grocery
stores when the doors open automatically! Obviously, radar is an extremely useful
technology.
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4.1 Types of Radar
All radar systems send out electromagnetic radiation in radio or microwave
frequencies and use echoes of that radiation to detect objects, but different systems use
different methods of emitting and receiving radiation. Pulse radar sends out short bursts
of radiation. Continuous wave radar sends out a constant signal. Synthetic aperture radar
and phased-array radar have special ways of positioning and pointing the antennas that
improve resolution and accuracy. Secondary radar detects radar signals that targets send
out, instead of detecting echoes of radiation.
4.2 Simple Pulse Radar
Simple pulse radar is the simplest type of radar. In this system, the transmitter
sends out short pulses of radio frequency energy. Between pulses, the radar receiver
detects echoes of radiation that objects reflect. Most pulse radar antennas rotate to scan a
wide area. Simple pulse radar requires precise timing circuits in the duplexer to prevent
the transmitter from transmitting while the receiver is acquiring a signal from the
antenna, and to keep the receiver from trying to read a signal from the antenna while the
transmitter is operating. Pulse radar is good at locating an object, but it is not very
accurate at measuring an object’s speed.
4.3 Continuous Wave (CW)Radar
Continuous-wave (CW) radar systems transmit a constant radar signal. The
transmission is continuous, so, except in systems with very low power, the receiver
cannot use the same antenna as the transmitter because the radar emissions would
interfere with the echoes that the receiver detects. CW systems can distinguish between
stationary clutter and moving targets by analyzing the Doppler shift of the signals,
without having to use the precise timing circuits that separates the signal from the return
in pulse radar. Continuous wave radar systems are excellent at measuring the speed and
direction of an object, but they are not as accurate as pulse radar at measuring an object’s
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position. Some systems combine pulse and CW radar to achieve both good range and
velocity resolution. Such systems are called Pulse-Doppler radar systems.
4.4. Synthetic Aperture Radar(SAR)
Synthetic aperture radar (SAR) tracks targets on the ground from the air. The
name comes from the fact that the system uses the movement of the airplane or satellite
carrying it to make the antenna seem much larger than it actually is. The ability of radar
to distinguish between two closely spaced objects depends on the width of the beam that
the antenna sends out. The narrower the beam is, the better its resolution. Getting a
narrow beam requires a big antenna. A SAR system is limited to a relatively small
antenna with a wide beam because it must fit on an aircraft or satellite. SAR systems are
called synthetic aperture, however, because the antenna appears to be bigger than it really
is. This is because the moving aircraft or satellite allows the SAR system to repeatedly
take measurements from different positions. The receiver processes these signals to make
it seem as though they came from a large stationary antenna instead of a small moving
one. Synthetic aperture radar resolution can be high enough to pick out individual objects
as small as automobiles.
Typically, an aircraft or satellite equipped with SAR flies past the target object. In inverse
synthetic aperture radar, the target moves past the radar antenna. Inverse SAR can give
results as good as normal SAR.
4.5. Phased Array Radar
Most radar systems use a single large antenna that stays in one place, but can
rotate on a base to change the direction of the radar beam. A phased-array radar antenna
actually comprises many small separate antennas, each of which can be rotated. The
system combines the signals gathered from all the small antennas. The receiver can
change the way it combines the signals from the antennas to change the direction of the
beam. A huge phased-array radar antenna can change its beam direction electronically
many times faster than any mechanical radar system can.
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4.6 RADAR APPLICATIONS
Civilian aircraft and maritime industries use radar to avoid collisions and to keep
track of aircraft and ship positions.
Military craft also use radar for collision avoidance, as well as for tracking
military targets.
Radar is also used for traffic safety.
Meteorologists use radar to learn about the weather.
Scientists use radar in several space-related applications.
4.7 Conclusion
This chapter explains the about the radar and types of the radar and why we are using the
radar and also the application of the radar is clearly explained.
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STEPPER MOTORS
A stepper motor is an electro-mechanical device which converts electrical pulses
into discrete mechanical movements. The shaft or spindle of a stepper motor rotates in
discrete step increments when electrical command pulses are applied to it in the proper
sequence. The motors rotation has several direct relationships to these applied input
pulses. The sequence of the applied pulses is directly related to the direction of motor
shafts rotation. The speed of the motor shafts rotation is directly related to the frequency
of the input pulses and the length of rotation is directly related to the number of input
pulses applied.
5.1 Stepper Motor Advantages and Disadvantages
Advantages
1 The rotation angle of the motor is proportional to the input pulse.
2 The motor has full torque at standstill (if the windings are energized)
3 Precise positioning and repeatability of movement since good stepper motors have
an accuracy of 3 – 5% of a step and this error is non cumulative from one
step to the next.
4 Excellent response to starting/stopping/reversing.
5 Very reliable since there are no contact brushes in the motor.Therefore the life of
the motor is simply dependant on the life of the bearing.
6 The motors response to digital input pulses provides open-loop control, making
the motor simpler and l less costly to control.
7 It is possible to achieve very low speed synchronous rotation with a load that is
directly coupled to the shaft.
8 A wide range of rotational speeds can be realized as the speed is proportional to
the frequency of the input pulses.
Disadvantages
1. Resonances can occur if not properly controlled.
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2. Not easy to operate at extremely high speeds.
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5.2 DC MOTORS VS. STEPPER MOTORS
•Stepper motors are operated open loop, while most DC motors are operated
closed loop.
•Stepper motors are easily controlled with microprocessors, however logic and
drive electronics are more complex.
•Stepper motors are brushless and brushes contribute several problems, e.g., wear,
sparks, electrical transients.
•DC motors have a continuous displacement and can be accurately positioned,
whereas stepper motor motion is incremental and its resolution is limited to the
step size.
•Stepper motors can slip if overloaded and the error can go undetected. (A few
stepper motors use closed-loop control.)
•Feedback control with DC motors gives a much faster response time compared to
stepper motors.
5.3 STEPPER MOTOR BASICS
Fig 5.1 stepper motor winding
Stpper Motor States For Motion The above figure is the cross-section view of a single-
stack variable-reluctance motor. The stator core is the outer structure and has six poles or
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teeth. The inner device is called the rotor and has four poles. Both the stator and rotor are
made of soft steel. The stator has three sets of windings as shown in the figure. Each set
has two coils connected in series. A set of windings is called a “phase”. The motor above,
using this designation, is a three-phase motor. Current is supplied from the DC power
source to the windings via the switches I, II, and, III.
Starting with state (1) in the upper left diagram, note that in state (1), the winding of
Phase I is supplied with current through switch I. This is called in technical terms, “phase
I is excited”. Arrows on the coil windings indicate the magnetic flux, which occurs in the
air-gap due to the excitation. In state I, the two starting poles on phase I being excited are
in alignment with two of the four rotor teeth. This is an equilibrium state. Next, switch II
is closed to excite phase II in addition to phase I. Magnetic flux is built up at the stator
poles of phase II in the manner shown in state (2), the upper right diagram. A counter-
clockwise torque is created due to the “tension” in the inclined magnetic flux lines. The
rotor will begin to move and achieve state (3), the lower left diagram. In state (3) the
rotor has moved 15°. When switch I is opened to de-energize phase I, the rotor will travel
another 15° and reach state (4). The angular position of the rotor can thus be controlled in
units of the step angle by a switching process. If the switching is carried out in sequence,
the rotor will rotate with a stepped motion; the switching process can also control the
average speed
STEP ANGLE
The step angle, the number of degrees a rotor will turn per step, is calculated as follows:
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5.4 Types of Stepper motor:
(1)Unipolar stepper motor
(2)Biipolar stepper motor
Unipolar stepper motor
Fig.5.2 A unipolar stepper motor
Unipolar stepping motors with 5 or 6 wires are usually wired as shown in the
schematic in Figure 1, with a center tap on each of two windings. In use, the center taps of
the windings are typically wired to the positive supply, and the two ends of each winding
are alternately grounded to reverse the direction of the field provided by that winding. The
motor cross section shown in Figure 1 is of a 30 degree per step motor -- the difference
between these two motor types is not relevant at this level of abstraction. Motor winding
number 1 is distributed between the top and bottom stator pole, while motor winding
number 2 is distributed between the left and right motor poles. The rotor is a permanent
magnet with 6 poles, 3 south and 3 north, arranged around its circumfrence. For higher
angular resolutions, the rotor must have proportionally more poles. The 30 degree per step
motor in the figure is one of the most common permanent magnet motor designs, although
15 and 7.5 degree per step motors are widely available. As shown in the figure, the current
flowing from the center tap of winding 1 to terminal a causes the top stator pole to be a
north pole while the bottom stator pole is a south pole. This attracts the rotor into the
position shown. If the power to winding 1 is removed and winding 2 is energised, the rotor
will turn 30 degrees, or one step. To rotate the motor continuously, we just apply power to
the two windings in sequence. Assuming positive logic, where a 1 means turning on the
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current through a motor winding, the following two control sequences will spin the motor
illustrated in Figure 1 clockwise 24 steps or 4 revolutions:
Note that the two halves of each winding are never energized at the same time. Both
sequences shown above will rotate a permanent magnet one step at a time. The top
sequence only powers one winding at a time, as illustrated in the figure above; thus, it
uses less power. The bottom sequence involves powering two windings at a time and
generally produces a torque about 1.4 times greater than the top sequence while using
twice as much power.
Bipolar stepper motor
Fig 5.4. A bipolar stepper motor
Bipolar permanent magnet and hybrid motors are constructed with exactly the same
mechanism as is used on unipolar motors, but the two windings are wired more simply,
with no center taps. Thus, the motor itself is simpler but the drive circuitry needed to
reverse the polarity of each pair of motor poles is more complex. The schematic in Figure
2 shows how such a motor is wired, while the motor cross section shown here is exactly
the same as the cross section shown in Figure 1. The drive circuitry for such a motor
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requires an H-bridge control circuit for each winding. Briefly, an H-bridge allows the
polarity of the power applied to each end of each winding to be controlled independently.
The control sequences for single stepping such a motor are shown below, using + and -
symbols to indicate the polarity of the power applied to each motor terminal:
Terminal 1a +---+---+---+---
Terminal 1b --+---+---+---+-
Terminal 2a -+---+---+---+--
Terminal 2b ---+---+---+---+
time --->
Note that these sequences are identical to those for a unipolar permanent magnet motor,
at an abstract level, and that avove the level of the H-bridge power switching electronics,
the control systems for the two types of motor can be identical. Note that many full H-
bridge driver chips have one control input to enable the output and another to control the
direction. Given such bridge chips, one for eachwinding, the following control sequences
will spin the motor identically to the control sequences given above:
Enable 1 1111111111111111
Direction 1 1100110011001100
Enable 2 1111111111111111
Direction 2 0110011001100110
time --->
To distinguish a bipolar permanent magnet motor from other 4 wire motors, measure the
resistances between the different terminals. It is worth noting that some permanent
magnet stepping motors have 4 independent windings, organized as two sets of two.
Within each set, if the two windings are wired in series, the result can be used as a high
voltage bipolar motor. If they are wired in parallel, the result can be used as a low voltage
bipolar motor. If they are wired in series with a center tap, the result can be used as a low
voltage unipolar motor.
- 24 -
5.5 Motor Control Circuitry
Fig 5.5 – magnetic field diagram
Current flowing through a coil produces a magnet field, which attracts a
permanent magnet rotor, which is connected to the shaft of the motor. The basic
principle of stepper control is to reverse the direction of current through the 2 coils of a
stepper motor, in sequence, in order to influence the rotor. Since there are 2 coils and 2
directions, that gives us a possible 4-phase sequence. All we need to do is get the
sequencing right and the motor will turn continuously. You may wonder how the stepper
can achieve such fine stepping increments with only a 4-phase sequence. The internal
arrangement of the motor is quite complex- the winding and core repeating around the
perimeter of the motor many times. The rotor is advanced only a small angle, either
forward or reverse, and the 4-phase sequence is repeated many times before a complete
revolution occurs.
Fig 5.6 – stepper motor basic control diagram
- 25 -
Let us return to the 4-phase sequence of reversing the current though the 2 coils. A
Bipolar stepper controller achieves the current reversal by reversing the polarity at the
two terminals of a coil. The Unipolar controller takes advantage of the center tap to
achieve the current reversal with a clever trick -- The Center tap is tied to the positive
supply, and one of the 2 terminals is grounded to get the current flowing one direction.
The other terminal is grounded to reverse the current. Current can thus flow in both
directions, but only half coils are energized at a time. Both terminals are never grounded
at the same time, which would energize both coils, achieving nothing but a waste of
power.
Conceptual Model of Unipolar Stepper Motor
Fig 5.7 – conceptual model of unipolar stepper motor
With center taps of the windings wired to the positive supply, the terminals of
each winding are grounded, in sequence, to attract the rotor, which is indicated by the
arrow in the picture. (Remember that a current through a coil produces a magnetic
field.) This conceptual diagram depicts a 90-degree step per phase.
- 26 -
In a basic "Wave Drive" clockwise sequence, winding 1a is de-activated and
winding 2a activated to advance to the next phase. The rotor is guided in this manner
from one winding to the next, producing a continuous cycle. Note that if two adjacent
windings are activated, the rotor is attracted mid-way between the two windings. The
following table describes 3 useful stepping sequences and their relative merits. The
sequence pattern is represented with 4 bits, a '1' indicates an energized winding. After the
last step in each sequence the sequence repeats. Stepping backwards through the
sequence reverses the direction.
WAVE STEPPING The wave stepping sequence is shown below.
STEP L1 L2 L3 L4 1 H L L L 2 L H L L
3 L L H L 4 L L L H
Wave stepping has less torque then full stepping. It is the least stable at higher speeds and as low power consumption.
FULL STEPPING The full stepping sequence is shown below.
STEP L1 L2 L3 L4 1 H H L L 2 L H H L 3 L L H H 4 H L L H
Full stepping has the lowest resolution and is the strongest at holding its position. Clock-wise and counter clockwise rotation is accomplished by reversing the step sequence.
HALF-STEPPING – A Combination Of Wave and Full Stepping
The half-step sequence is shown below. STEP L1 L2 L3 L4 1 H L L L 2 H H L L 3 L H L L 4 L H H L 5 L L H L 6 L L H H 7 L L L H 8 H L L H
- 27 -
The half-step sequence has the most torque and is the most stable at higher speeds. It also has the highest resolution of the main stepping methods. It is a combination of full and wave stepping.
5.6 Conclusion
This chapter is explained about the stepper motor basics and why we are using stepper motor compare to dc motor and types of the stepper motor.
- 28 -
RS232
All IBM PC and compatible computers are typically equipped with two
serial ports and one parallel port. Although these two types of ports are used for
communicating with external devices, they work in different ways.
A parallel port sends and receives data eight bits at a time over 8 separate wires.
This allows data to be transferred very quickly; however, the cable required is more
bulky because of the number of individual wires it must contain. Parallel ports are
typically used to connect a PC to a printer and are rarely used for much else.
A serial port sends and receives data one bit at a time over one wire. While it
takes eight times as long to transfer each byte of data this way, only a few wires are
required. In fact, two-way (full duplex) communications is possible with only three
separate wires - one to send, one to receive, and a common signal ground wire.The serial
port on our PC is a full-duplex device meaning that it can send and receive data at the
same time. In order to be able to do this, it uses separate lines for transmitting and
receiving data. Some types of serial devices support only one-way communications and
therefore use only two wires in the cable - the transmit line and the signal ground.
RS-232 stands for Recommend Standard number 232 and C is the latest revision
of the standard. The serial ports on most computers use a subset of the RS-232C standard.
The full RS-232C standard specifies a 25-pin "D" connector of which 22 pins are used.
Most of these pins are not needed for normal PC communications, and indeed, most new
PCs are equipped with male D type connectors having only 9 pins.
6.1 PC interface section
Fig 6.1 – RS-232 Connecter diagram
The above shown connector known as 9-pin, D-type male connector is used for
RS232 connections. The pin description is given in the following table.
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12345
6789
Pin number Common
Name
RS232
name
Description Signal
direction
1 /CD CF Received line signal detector IN
2 RXD BB Received data IN
3 TXD BA Transmitted data OUT
4 /DTR CD Data terminal ready OUT
5 GND AB Signal ground --
6 /DSR CC Data set ready IN
7 /RTS CA Request to send OUT
8 /CTS CB Clear to send IN
9 -- CE Ring indicator IN
Table 6.1 – RS-232 pin details
We cannot simply connect our system to this terminal with out providing proper
hand shaking signal. For communicating with RS-232 type equipment, the /RTS of the
connector is simply looped into the /CTS, so /CTS will automatically be asserted when
/RTS is asserted internally. Similarly the /DTR is looped into /DSR and /CD, so when PC
asserts its /DTR output the /DSR and /CD inputs are automatically be asserted. These
connections do not provide for any hardware hand shaking. They are necessary to get the
PC and our system talk each other. The connection diagram is shown below.
Fig 6.2 – RS-232 Interface diagram
- 30 -
Tx 3 Rx 2 /CTS 8 /RTS 7 /DSR 6 /DTR 4 /CT 1
GND 5
2 Rx3 Tx
5 GND
6.2 RS – 232 serial interface
The MAX232 I.C convert input TTL level into RS-232C standard level and connected
to PC through 9-pin D-type connector. Now discuss about standards of RS232 and Serial
communication through RS232
MAX232 circuit diagram
Fig 6.3 – RS-232 Circuit diagram
RS-232 logic levels are indicated by positive and negative voltages, rather than by
the positive-only signals of 5V TTL and CMOS logic. At an RS-232 data output (TD), a
logic 0 is defined as equal to or more positive than +5V, and a logic 1 is defined as equal
to or more negative than –5V. In other words, the signals use negative logic, where the
more negative voltage is logic 1.
The control signals use the same voltages, but with positive logic. A positive
voltage indicates that the function is on, or asserted, and a negative voltage indicates that
the function is off, or not asserted.
- 31 -
RS-232 interface chips invert the signals. On a UART’s output pin, a logic-1 data
bit or an off control signal is near 5V, which results in a negative voltage at the RS-232
interface. Logic – 0 data bit or on control signal is near 0V, resulting in a positive
voltage at the RS-232 interface. Because an RS-232 receiver may be at the end of a long
cable, by the time the signal reaches the receiver, its voltage may have attenuated or have
noise riding on it. To allow for this, the minimum required voltages at the receiver are
less than at the driver. An input more positive than +3V is a logic 0 at RD, or On at a
control input. An input more negative than –3V is a logic 1 at RD, or Off at a control
input. According to the standard, the logic level of an input between –3V and +3V is
undefined.
The noise margin, or voltage margin, is the difference between the output and
input voltages. RS-232’s large voltage swings result in a much wider noise margin than
5V TTL logic. For example, even if an RS-232 driver’s output is the minimum +5V, it
can attenuate or have noise spikes as large as 2V at the receiver and still be a valid logic
0. Many RS-232 outputs have much wider voltage swings: 9 and 12V are common.
These in turn give much wider noise margin. The maximum allowed voltage swing is
15V, though receivers must handle voltages as high as 25V without damage.
Two other terms used in relation to RS-232 are Mark and Space. Space is logic 0,
and Mark is logic 2. These refer to the physical marks and spaces made by the
mechanical recorders used years ago to log binary data.
TIA/EIA-232 includes both minimum and maximum timing specifications. All of
the many RS-232 interface chips meet these specifications. The specified slew rate limits
the maximum bit rate of the interface. Slew rate is a measure of how fast the voltage
changes when the output switches and describes an output’s instantaneous rate of voltage
change. The slew rate of an RS-232 driver must be 30 Volts per microsecond or less. The
advantage of limiting slew rate is that it improves signal quality by virtually eliminating
problems due to voltage reflections that occur on long links that carry signals. With fast
rise and fall times. But the slew rate also limits a link’s maximum speed. At 30 V/s, an
output requires 0.3 microsecond to switch from +5V to –5V. RS-232’s specified
- 32 -
maximum bit rate is 20 kbps, which translates to a bit width of 50 microseconds, or 166
times the switching time at the fastest allowed slew rate.
6.3 Conclusion
Here this chapter is clearly explained how the communication is done between PC and
RS 232 and also the Rs 232 circuit diagram.
- 33 -
HARDWARE
7.1 Stepper motor driver circuit
Fig7.1 stepper motor drive circuit
When the output of the controller is high, the base current Iв flows in to base of
the transistor, thus providing voltage drop more then 0.7V across the Vвe junction, thus
the transistor goes in to saturation mode. So the Ic is maximum and the voltage drop
across the Vce junction is zero. I.e. the input to MOSFET is zero. So the MOSFET will
not conduct and stepper motor coil will not energize.
If the output of the controller is low, the base current Iв is zero, thus providing
voltage drop less then 0.1V across the Vвe junction, thus the transistor goes in to cut-off
mode. So the Ic is minimum and the voltage drop across the Vce junction is maximum.
I.e. the input to MOSFET is almost Vcc. So the MOSFET will conduct and stepper motor
coil get energized.
is For driving of motor coils, we used IRF540 MOSFET, which are having low on-state
resistance so that the dissipation is less, fast switching and low thermal resistance. This
MOSFET is driven by BC548 transistor. For each motor four MOSFET sections are
required.
- 34 -
7.2 Optical Transducer
fig 7.2 IR TX&RX
7.2.1 IR transmitter:
IR transmitter is an optical transducer which converts electrical signals into IR
rays. This IR rays are transmitted into the space(in all directions) for sensing the presence
of target.
7.2.2 IR receiver:
IR receiver is an optical transducer which converts IR rays into electrical signals.
When a target is intersected by emitted rays of the IR transmitter (RADAR antenna), a
portion of intersected rays are reflected back which is collected by IR receiver. This
information is sent to micro controller 89C51.Thus ensuring the presence of target in
space.
7.3 COMPARATOR:
It consists of two stages i.e signal buffer and level converter
Fig 7.3 – signal buffer and level comparator
- 35 -
In the first stage the output of the op-amp is connected directly to inverting input
so that it acts as a voltage follower or buffer. This will prevent any loading of signal by
the next stage.
In the second stage a variable voltage reference is connected to non-inverting
input and signal is connected to inverting input. If the signal is lower then the reference
the output will go high (+5V), or if the signal is higher then the reference then the output
goes low (0V). Normally the signal level will be 2V for low and 2.5V for high. After
comparator the output will be 0V for high input and +5Vfor low input i.e. the level is
converted.
7.4 Firing indicator
Fig 7.4 – firing indicator circuit diagram
The fire signal from micro controller is a pulse output of 1sec. I.e. the output is
high for 1sec. When the output of the controller is high, the base current Iв flows in to
base of the transistor, thus providing voltage drop more then 0.7V across the Vвe
junction, thus the transistor goes in to saturation mode. So the Ic is maximum and the
LED will glow and simultaneously, buzzer gives a beep sound
- 36 -
7.5. Slot Sensor
Fig 7.5 slot sensor
It consists of IR light emitting diode(LED1) and phototransistors(Q1). It is used to
detect the position of the target. When the diode is in off state, no light falls on the base
of phototransistor. So, it acts as open circuit. Thus output is high. This implies that the
antenna and gun are present in their respective reference positions.
When light falls on the photo diode that is on the base of the phototransistor then
Q acts as short circuit and thus the output is low. This implies the antenna and gun are
away from their respective reference positions.
7.6 Power supply
Fig 7.6 – power supply
- 37 -
Power supply unit provides 5V regulates power supply to the systems. It consists
of two parts namely,
1. Rectifier
2. Monolithic voltage regulator
1. Rectifier
Here the step down transformer 230-0v/9-0-9 and gives the secondary current up
to 500mA, to the Rectifier. The Transformer secondary is provided with a center tap.
Hence the voltage V1 and V2 are equal and are having a phase difference of 1800. So it
is anode of Diode D1 is positive with respect to the center tap, the anode of the other
diode d2 will be negative with respect to the center tap. During the positive half cycle of
the supply D1 conduct’s and current flows through the center tap D1 and load. During
this period D2 will not conduct as its anode is at a negative potential. During the
negative half cycle of the supply voltage, the voltage on the diode D2 will be positive and
hence D2 conducts. The current flows through the transformer winding, Diode D2 and
load. It is to be noted that the current i1 and i2 are flowing in the same direction in load.
The average of the two current i1 and i2 flows through the load producing a
voltage drop, which is the D.C. output voltage of the rectifier. Using capacitor filters the
ripple in the out waveform can be minimized. The voltage can be regulated by using
monolithic IC voltage regulators.
2. Monolithic IC voltage regulator:
A voltage regulator is a circuit that supplies a constant voltage regardless of
changes in load currents. Although voltage regulators can be designed using op-amps, it
is quicker and easier to use IC voltage regulators. Furthermore, IC voltage regulators are
versatile and relatively inexpensive and are available with features such as programmable
output, current/voltage boosting, internal short-circuit current limiting, thermal shutdown
and floating operation for high voltage applications
Here we are using 7800 series voltage regulators. The 7800 series consists of 3-
terminal +ve voltage regulators with seven voltage options. These ICs are designed as
fixed voltage regulators and with adequate heat sinking can deliver output currents in
excess of 1A. Although these devices do not require external components, such
components can be used to obtain adjustable voltages and currents. For proper operation
- 38 -
a common ground between input and output voltages is required. In addition, the
difference between input and output voltages (Vi – Vo) called drop out voltage, must be
typically 1.5V even during the low point as the input ripple voltage. Further more, the
capacitor Ci is required if the regulator is located an appreciable distance from a power
supply filter. Even though Co is not needed, it may be used to improve the transient
response of the regulator.
Typical performance parameters for voltage regulators are line regulation, load
regulation, temperature stability and ripple rejection. Line regulation is defined as the
change in output voltage for a change in the input voltage and is usually expressed in
milli volts or as a percentage of Vo. Temperature stability or average temperature
coefficient of output voltage (TCVo) is the change in output voltage per unit change in
temperature and is expressed in either milli volts/ºC or parts per million (PPM/ºC).
Ripple rejection is the measure of a regulator’s ability to reject ripple voltage. It is usually
expressed in decibels. The smaller the values of line regulation, load regulation and
temperature stability the better the regulation.
7.7 Conclusion
This chapter has explained the which hardware components and blocks are used in this
project and their working.
- 39 -
RFID TAGSIntroduction:
At the time of world war the military had found difficulties in tracing the enemies
and their activities. This difficulty had lead to the invention of RADAR.
To face new challenges in the present day situation in Military applications
unmanned systems are more accurate, flexible and reliable. One such system is the
MC BASED UNMANNED ANTI AIRCRAFT MISSILE WITH RADAR
USING RFID.
RADAR (Radio detection and Ranging), a remote detection system, is used to
locate and identify objects. Radar signals bounce off objects in their path and the Radar
system detects the echoes of signals that return. RADAR can determine a number of
properties of a distant object, such as its distance, speed, direction of motion and shape. It
can detect objects out of range of sight and works in all weather conditions, making it a
vital and versatile tool for many industries.
A radar system starts by sending out electromagnetic radiation, called the
Signal.The signal bounces off objects in its path. When the radiation bounces back part of
the signal returns to the Radar system; this echo is called the Return.The Radar system
detects the Return and depending on the sophistication of the system, simply reports the
detection or analyzes the signal for more information.
RFID or Radio Frequency identification is a technology that enables the tracking
or identification of objects using IC based tags with an RF circuit and antenna, and RF
readers that "read" and in some case modify the information stored in the IC memory.
Radio frequency identification (RFID) is a general term that is used to describe a
system that transmits the identity (in the form of a unique serial number) of an object
wirelessly, using radio waves.
RFID technologies are grouped under the more generic Automatic Identification
(Auto ID) technologies.
The RF tags could be divided in two major groups:
Passive tags
The power to activate the tag microchip is supplied by the reader through the tag
antenna when the tag is in the interrogation zone of the reader, as is the timing pulse
- 40 -
Active RFID tags
Active RFID tags has a battery in them and are therefore more capable in terms of
range and data handling.
Frequency use
There are four commonly used frequencies: low frequency (LF) 125/134.2 kHz,
high frequency (HF) 13.56 MHz, ultra high frequency (UHF) (including 869 and 915
MHz) and microwave (at 2450 MHz, a band familiar to ISPs).
- 41 -
SOFTWARE
9 Assembly Programming Language (APL)
;------------------------------------------------------------------------------------------------------------;>;> TITLE : RADAR SIMILATION WITH OPTICAL SENSOR;> TARGET : AT89C51;> VERSION : VER-01;> STARTED : 05-03-2005;>;------------------------------------------------------------------------------------------------------------;>;> INCLUDES : $MOD51;>;------------------------------------------------------------------------------------------------------------;>;> HARD WARE DETAILS :;> RADAR MOTOR CONTROL - P2.0 TO P2.3;> GUN MOTOR CONTROL - P2.4 TO P2.7;> COMMUNICATION O.K. IND COK BIT P1.7;> I.R.FEED BACK IRF BIT P1.1;> CODE MATCH INPUT CMI BIT P3.7;> ANTENNA HOME SENSOR AHS BIT P1.4;> GUN HOME SENSOR GHS BIT P1.5;> FIRING CONTROL FNC BIT P1.6;> FIRING CONTROL FNC1 BIT P1.2;> SLAVE RESET CONTROL SRST BIT P3.5;>;------------------------------------------------------------------------------------------------------------;>;> FLAGS : KEY_RLS BIT 00H
- 42 -
MOT_DIR BIT 01H SEND_ANG BIT 02H ENEMY BIT 03H ABS_LOCK BIT 04H ZERO_LOCK BIT 05H;>;------------------------------------------------------------------------------------------------------------;>;> VARIABLES : STEP_CNT DATA 30H MOT_FB DATA 32H RAD_CNTL DATA 33H RAD_CNTH DATA 34H GUN_CNTL DATA 35H GUN_CNTH DATA 36H ABS_CNTL DATA 37H ABS_CNTH DATA 38H STEP_CNTG DATA 39H P2_BUF DATA 3AH ROT_CNT1 DATA 3BH ROT_CNT2 DATA 3CH;>;------------------------------------------------------------------------------------------------------------;>;> VECTOR ADDRESESS: ORG 0000H ljmp INITIALISATION
ORG 000BH reti
ORG 0023H ; serial interrupt; push ACC push PSW
jbc RI, RECEIVE_DATA ajmp SKIP_CHKS RECEIVE_DATA: cpl COK mov MOT_FB, SBUF setb SEND_ANG SKIP_CHKS: pop PSW; pop ACC
inc ROT_CNT1 mov A, ROT_CNT1 cjne A, #00H, SKIP_CY_CNT inc ROT_CNT2 mov A, ROT_CNT2SKIP_CY_CNT:
mov A, ROT_CNT2 cjne A, #01H, CP_REV_CNT1 mov A, ROT_CNT1 cjne A, #2CH, CP_REV_CNT1CP_REV_CNT1: jc CP_REV_CNT jnb MOT_DIR, CP_REV_CNT2 lcall BRING_HOME clr ENEMY setb FNC setb FNC1CP_REV_CNT2: cpl MOT_DIR mov ROT_CNT2, #00H mov ROT_CNT1, #00HCP_REV_CNT:
jb MOT_DIR, MOVE_MOT_FD lcall MOVE_FRWD lcall DLY2 inc RAD_CNTL mov A, RAD_CNTL cjne A, #00H, MOVE_MOT_FD inc RAD_CNTHMOVE_MOT_FD:
jnb MOT_DIR, MOVE_MOT_BD lcall MOVE_REV
- 45 -
lcall DLY2 dec RAD_CNTL mov A, RAD_CNTL cjne A, #0FFH, MOVE_MOT_BD1 dec RAD_CNTHMOVE_MOT_BD1: mov A, RAD_CNTH cjne A, #0FFH, MOVE_MOT_BD mov A, RAD_CNTL cjne A, #0FFH, MOVE_MOT_BD mov RAD_CNTL, #00H mov RAD_CNTH, #00HMOVE_MOT_BD:
; mov A, MOT_FB; cjne A, #0BBH, MOVE_MOT_HM; mov MOT_FB, #00H; lcall BRING_HOME; mov RAD_CNTL, #00H; mov RAD_CNTH, #00H;MOVE_MOT_HM:
; mov A, MOT_FB; cjne A, #0CCH, STOP_FIRING; mov MOT_FB, #00H; clr ENEMY; setb FNC; setb FNC1;STOP_FIRING: mov A, GUN_CNTH cjne A, ABS_CNTH, DONT_FIRE_GUN mov A, GUN_CNTL cjne A, ABS_CNTL, DONT_FIRE_GUN orl P2_BUF, #0F0H orl P2, #0F0H jnb ENEMY, DONT_FIRE_ON cpl FNC cpl FNC1DONT_FIRE_ON: ljmp DONT_SEND_INFDONT_FIRE_GUN: jc MOVE_GUN_FOR jnc MOVE_GUN_REV
MOVE_GUN_FOR:
- 46 -
setb FNC setb FNC1 lcall MOVE_G_FRWD inc GUN_CNTL mov A, GUN_CNTL cjne A, #00H, MOVE_GUN_REV1 inc GUN_CNTHMOVE_GUN_REV1: ljmp DONT_SEND_INFMOVE_GUN_REV: setb FNC setb FNC1 lcall MOVE_G_REV dec GUN_CNTL mov A, GUN_CNTL cjne A, #0FFH, DEC_GUN_CNT1 dec GUN_CNTHDEC_GUN_CNT1: mov A, GUN_CNTH cjne A, #0FFH, DONT_SEND_INF mov A, GUN_CNTL cjne A, #0FFH, DONT_SEND_INF mov GUN_CNTL, #00H mov GUN_CNTH, #00HDONT_SEND_INF:
jb ABS_LOCK, RESET_GUN mov A, ABS_CNTH cjne A, #00H, RESET_GUN mov A, ABS_CNTL cjne A, #00H, RESET_GUN setb ABS_LOCK lcall BRING_HOME_GUN orl P2_BUF, #0FH mov P2, P2_BUF mov GUN_CNTL, #00H mov GUN_CNTH, #00HRESET_GUN:
