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INFRARED OBJECT POSITION LOCATOR

OLADAPO, OPEOLUWA AYOKUNLE EEG/2001/129SUBMITTED TO DEPARTMENT OF ELECTRONIC AND ELECTRICAL ENGINEERING OBAFEMI AWOLOWO UNIVERSITY, ILE IFE OSUN STATE, NIGERIA IN PARTIAL FULFILLMENT FOR THE AWARD OF BACHELOR OF SCIENCE IN ELECTRONIC AND ELECTRICAL ENGINEERING

JANUARY 2008

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CHAPTER 1 INTRODUCTION There are numerous locating, tracking and monitoring protocols in use today, for use in conjunction with physical boundaries and fences, as necessary to locate, track and monitor the location and proximity of an object relative to the physical boundary. Such objects may be animate or inanimate, such as pets, livestock, valuables, inventory, equipment, personnel, and the like. Tracking systems have in recent times been on increasing demand this is because security is of paramount importance and the use of tracking systems is one of the simplest and most effective ways in security systems. A position location system is used to determine the location or direction of a target on a near-continuous basis. An ideal tracking system would maintain contact and constantly update the target's bearing (azimuth), range and elevation. Locating an object to be tracked may be readily achieved using transmitter/receiver-based technology. Many devices used by police, security, and military organizations, including user-wearable, gun mounted, vehicle-mounted, missile-mounted, and orbital systems, exploit some form of infrared detection technology.

Possible uses for this project include security surveillance for inside buildings and surrounding areas. By using an infrared camera, the design can also have military applications. The camera can be attached to a gun turret which could then track moving targets.

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1.1

OBJECTIVE The aim of this project is to design and build a device that will track an object

(IR transmitter) in 3600 azimuth using an IR tracking system. The object position locator is to comprise of an IR receiver, sweep dish and an intelligent controller (implemented with Microcontroller PIC 16F877A), which is to activate the scanning process of the sweep dish and also determine the position of the target. The IR transmitter is attached to the object to be tracked while the IR receiver receives signal sent by the transmitter and sends it to the computer. Tracking is done by comparing signal strengths received from the IR receiver. This is to achieve a continuous monitoring process to cause a real-time tracking of the object.

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CHAPTER 2 LITERATURE REVIEW The purpose of this project is to develop a motion tracking device, which will be able to recognize an object, and follow its motion on a horizontal plane. To reach this goal, the motion tracking algorithm must perform within certain limits to keep up with the real-time. Therefore, the most important factors of the project in these regards are speed, cost and transmission signal strength

2.1

VARIOUS DESIGNS AND THEIR LIMITATIONS Commercially, past research on the project have been carried out using

different tracking methods. These methods include: Radio Frequency Tracking, Global Positioning System Tracking and Infrared Tracking Technologies.

2.1.1

RADIO FREQUENCY (RF) IDENTIFICATION TRACKING This method is commonly used to implement the tracking systems by various

engineering institutes in design. Normally, a suitable frequency band for the design would be selected considering factors such as cost, interference with other transmitting stations around, effectiveness with the range of operation being considered e.t.c. The Radio frequency design was first implemented using radio frequency (RF) tags by Harry Stockman. He used the RF tags to reflect power ensuring continuous reception from the receiver. Radio path between the transmitter and receiver obstructed by surface with sharp irregular objects even when line-of-sight (LOS) dont exist, waves bend around the objects by diffraction. It has an advantage of good enough range for most applications

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but also has disadvantages which include issue of cost, multi-path, fading and interference (Steven Depp et al, 2002)

2.1.2

GLOBAL POSITIONING SYSTEM (GPS) TRACKING This is another very effective method used in tracking objects. The GPS is a

space-based radio-positioning and time transfer system developed in the early 1940s by Decca Navigator. The GPS has three major segments: Space Division, Control Segment, and User Equipment Division. As a universal positioning system, GPS provides several characteristics not found in other existing equipment which will enhance the conduct of mission operations: Extremely accurate (3-dimensional) position, velocity and time (PVT) determination; a worldwide common grid easily converted to other local data; passive, all weather operation; real-time and continuous information; and survivability in a hostile environment (Lockheed et al, 1999). A GPS receiver's job is to locate four or more satellites in space, figure out the distance to each, and use this information to deduce its own location. This operation is based on a simple mathematical principle called trilateration1. One of the limitations of the GPS tracking method is that certain atmospheric factors (ionization) and other sources of error can affect the accuracy of GPS receivers.

2.1.3

INFRARED (IR) TRACKING Infrared technology is one of the earliest tracking methods discovered in the

18th century by William Herschel. Infrared light consists of electromagnetic radiation that is too low in frequency (i.e., too long in wavelength) to be perceived by the human eye, yet is still too high in frequency to be classed as microwave radio. Infrared (IR) light that is just beyond the human visual limit (>1.0 1014 to 4.0 1

A method of determining the relative position of object using geometry of triangles

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1014 Hz) is termed near IR, while light farther from the visible spectrum is divided into middle IR, far IR, and extreme IR. Military and security systems utilize mostly near IR and a narrow band in the far IR centered on 3.0 1013 Hz, because the Earth's atmosphere happens to be transparent to IR radiation2 Infrared tracking technology employs the transmitter-receiver model. It is very cost effective and easy to manage. Its main limitation is in its signal strength coverage in transmission.

2.2

DESIGN IMPROVEMENTS The Infrared tracking Technology was selected because of its cost

effectiveness and flexibility. The Transmitter-Receiver model can be easily implemented on a small scale level. The IR tracking will be improved using a dish to focus the IR radiation on the receiver to enable a better reception of the infrared signals sent by the infrared transmitter.

2.3

HARDWARE COMPONENTS The hardware components used in the IR tracking implementation include;

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An Infrared light-emitting diode (LED) A Phototransistor (used as an infrared receiver) Current Amplifier (ULN2003) Field Effect Transistors (FET) Stepper motors (1) PIC 16F877A microcontroller. A brief description and theory of the hardware components employed is

discussed in the following sections.2

Spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay

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2.3.1

PIC 16F877A MICROCONTROLLER A microcontroller is a computer-on-a-chip developed by Intel3. It is a type of

microprocessor emphasizing high integration, low power consumption, selfsufficiency and cost-effectiveness, in contrast to a general-purpose microprocessor (the kind used in a PC). PIC 16F877 is a 40-pin 8-Bit CMOS FLASH Microcontroller from Microchip. The core architecture is high-performance RISC CPU with only 33 in-out pins. Since it follows the RISC architecture, all single cycle instructions take only one instruction cycle except for program branches which take two cycles. 16F877A comes with 3 operating speeds with 4, 8, or 20 MHz clock input. Since each instruction cycle takes four operating clock cycles, each instruction takes 0.2 ms when 20MHz oscillator is used.

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largest semiconductor company and inventor of the X86 series of microprocessors

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Figure 2.1

PIC16F877A Microcontroller

In addition to the usual arithmetic and logic elements of a general purpose microprocessor, the microcontroller typically integrates additional elements such as read-write memory for data storage, read-only memory, such as flash for code

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storage, EEPROM (Electrically Erasable Programmable Read Only Memory), for permanent data storage, peripheral devices, and input/output interfaces. At clock speeds of 20MHz or even lower, microcontrollers often operate at very low speed compared to modern day microprocessors, but this is adequate for typical applications. They consume relatively little power (milliwatts), and will generally have the ability to sleep while waiting for a peripheral event such as a button press to wake them up again to do something. Power consumption while sleeping is a few nanowatts, making them ideal for low power and long lasting battery applications. The PIC16F877A microcontroller is a single integrated circuit, also with the following features: serial input/output such as serial ports (MCCP, USARTs), parallel input/output such as (PSP) other serial communications interfaces like IC, Serial Peripheral Interface and Controller Area Network for system interconnect peripherals such as 3 timers, event counters, 2 PWM generators, and watchdog 368 bytes of volatile memory (RAM) for data storage ROM, EPROM, 256 bytes of EEPROM, 8K flash memory for program and operating parameter storage a clock generator - an oscillator for a quartz timing crystal eight 10-bit analogue-to-digital modules in-circuit programming and debugging support 2.3.2 STEPPER MOTOR A stepper motor is an electromechanical device which converts electrical pulses into discrete mechanical movements. The shaft or spindle of a stepper motor 9

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. A motor that rotates in short and essentially uniform angular movements rather than continuously; typical steps are 30, 45, and 90; the angular steps are obtained electromagnetically rather than by the ratchet and pawl mechanisms of stepping relays. A stepper motor is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps, for example, 200 steps. Thus the motor can be turned to a precise angle.

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Figure 2.2

Stepper Motor

When energized in a programmed manner by a voltage and current input, usually dc, a step motor can index in angular or linear increments. With proper

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control, the output steps are always equal in number to the input command pulses. According to Smith (1999), each pulse advances the rotor shaft one step increment and latches it magnetically at the precise point to which it is stepped. Advances in digital computers and particularly microcomputers revolutionized the controls of step motors. These motors are found in many industrial control systems, and large numbers are used in computer peripheral equipment, such as printers, tape drives, capstan drives, and memory-access mechanisms. Step motors are also used in numerical control systems, machine-tool controls, process control, and many systems in the aerospace industry.

There are many types of step motors. Most of the widely used ones can be classified as variable-reluctance, permanent-magnet, or hybrid permanent-magnet types. A variable-reluctance step motor is simple to construct and has low efficiency. The permanent-magnet types are more complex to construct and have a higher efficiency

The advantages of the stepper motor are as listed below: 1. The rotation angle of the motor is proportional to the input pulse. 2. The motor has full torque at standstill. 3. Precise positioning and repeatability of movement. 4. Excellent response to starting/stopping/reversing. 5. Very reliable since there are no contact brushes in the motor. 6. The motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.

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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.

The stepper motor also has some disadvantages as stated below; 1. Resonances can occur if not properly controlled. 2. Not easy to operate at extremely high speeds.

2.3.3

INFRARED TRANSMITTER The transmitter usually is a battery powered handset. It should consume as

little power as possible, and the IR signal should also be as strong as possible to achieve an acceptable control distance. Preferably it should be shock proof as well. Many chips are designed to be used as IR transmitters. The older chips were dedicated to only one of the many protocols that were invented. Nowadays very low power microcontrollers are used in IR transmitters for the simple reason that they are more flexible in their use. When no button is pressed they are in a very low power sleep mode, in which hardly any current is consumed. The processor wakes up to transmit the appropriate IR command only when a key is pressed.

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Figure2.3

Infrared Light Emitting Diode

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2.3.4

PHOTOTRANSISTOR Like diodes, all transistors are light-sensitive. Phototransistors are designed

specifically to take advantage of this fact. The most-common variant is an NPN bipolar transistor with an exposed base region. Here, light striking the base replaces what would ordinarily be voltage applied to the base, so a phototransistor amplifies variations in the light striking it. Note that phototransistors may or may not have a base lead (if they do, the base lead allows you to bias the phototransistor's light response.)

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Figure 2.4

Phototransistor

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2.3.5

INFRARED RECEIVER Infrared receivers pick up infrared signals within line-of-sight, and within 30

feet or so, and turn the signal into electrical impulses. These electrical impulses can be carried around the home on wires and then turned back into infrared signals by emitters. Many different receiver circuits exist on the market. The most important selection criterion is the modulation frequency used.

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Figure 2.5

Block diagram representation of the Infrared receiver

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Figure 2.5 is a typical block diagram of such an IR receiver; everything is built into one single electronic component. The received IR signal is picked up by the IR detection diode on the left side of the diagram. This signal is amplified and limited by the first 2 stages. The limiter acts as an AGC circuit to get a constant pulse level, regardless of the distance to the handset and the AC signal is sent to the Band Pass Filter. The Band Pass Filter is tuned to the modulation frequency of the handset unit. Common frequencies range from 30 kHz to 60 kHz in consumer electronics. The next stages are a detector, integrator and comparator. The purpose of these three blocks is to detect the presence of the modulation frequency. If this modulation frequency is present the output of the comparator will be pulled low.

2.3.6

FIELD EFFECT TRANSISTOR (FET) Such a transistor operates on the principle of repulsion or attraction of charges

due to a superimposed electric field. It is basically a transistor, with three or more electrodes, in which the output current is controlled by a variable electric field. Amplification of current is accomplished in a manner similar to the grid control of a vacuum tube. Field-effect transistors operate more efficiently than bipolar types, because a large signal can be controlled by a very small amount of energy. The field-effect transistor (FET) is a type of transistor that relies on an electric field to control the shape and hence the conductivity of a 'channel' in a semiconductor material. It is basically used for weak-signal amplification (for example, for amplifying wireless signals). The device can amplify analog or digital signals. It can also switch DC or function as an oscillator. In the FET, current flows along a

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semiconductor path called the channel4. At one end of the channel, there is an electrode called the source. At the other end of the channel, there is an electrode called the drain. The physical diameter of the channel is fixed, but its effective electrical diameter can be varied by the application of a voltage to a control electrode called the gate. The conductivity of the FET depends, at any given instant in time, on the electrical diameter of the channel. A small change in gate voltage can cause a large variation in the current from the source to the drain, thus the FET amplifies signals.

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Medium for transmission used in semiconductor devices

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CHAPTER 3 METHODOLOGY The various methods used in the implementation of the infrared (IR) position locator include; the search algorithm, stepper motor controlling, IR transmitter and receiver range detection and the interconnection of all the components. These methods are as enumerated in the following sections.

3.1

SEARCH ALGORITHM The algorithm being used for tracking involves the detection of the point of

maximum strength of the signal transmitted from the transmitter. The receiver in conjunction with the program (written and executed by PIC 16F877A) used to detect the point of maximum signal strength detects the point of maximum strength and the program written for the proper stepping of the motor is executed so as to give the dish instructions on the proper direction to point towards. A flowchart showing the control process is as shown in Figure 3.3.

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Figure 3.1

The Control Process

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Figure 3.2

Model plot of Signal Strength Vs Azimuth

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START

Signal

Input

Data Acquisition INITIALSIGNAL strength = A

SIGNAL strength 2 = B

IS A>B ? YESS OUTPUT=A STOP

Figure 3.3

Flowchart Process Showing Signal Comparisons

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The receiver sends various analogue inputs of the signal strengths into the PICs analogue-to-digital (A/D) converter which converts the signals into digital form that can be easily used for comparison and the detection of the maximum point of signal strength. This same digital form is translated and used for the proper stepping of the motor for directing the dish and the receiver. The sample of the code written for controlling the stepper motor and for detecting the point of maximum signal strength is shown in appendix A1.

3.2

STEPPER MOTOR CONTROL The stepper motor being used is the PJJQ113ZA-P Matsushita Line feed

motor which is a unipolar stepper motor having a step size of 7.5 degrees, 48 steps per revolution, resistance of 36 ohms and a gear diametrical pitch of 50. The stepper motor has six wires (out of which 2 are common) and four separate electromagnets which were used to turn the motor. Each electromagnet was energized one at a time by giving current to its corresponding coil. Four of those wires were each connected to one end of one coil. The extra wire (or 2) is called "common." To operate the motor, the "common" wires were connected to the supply voltage, and the other four wires are connected to ground through transistors, so the transistors control whether current flows or not. The microcontroller was used to activate the transistors in the right sequence. To drive the motor forward by one step (7.5o) the following sequence of signals needs to be applied to the coil connections:

Step

Q1 Q2 Q3 Q4 25

1 2 3 4 Repeat step 1 etc.

1 0 0 0

0 0 1 0

0 1 0 0

0 0 0 1

To drive the motor backwards by one step the sequence is:

Step 1 2 3 4 Repeat step 1 etc.

Q1 1 0 0 0

Q2 0 0 1 0

Q3 0 0 0 1

Q4 0 1 0 0

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IR TRANSMITTER3V IR LED Powered by Batteries

RECEIVER

MICRO CONTROLLER PIC16F877A

STEPPER MOTORS

Figure 3.4

Block diagram showing the control movement of the sweep dish

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3.3

INFRARED (IR) TRANSMITTER AND RECEIVER RANGE DETECTION

The maximum permissible range of operation of the receiver was tested and discovered to be 35 meters. The testing was carried out using the principle of line-ofsight. The distance between the transmitter and receiver was increased gradually and the signal strength received was detected. The maximum permissible range was chosen as the distance at which the signal strength becomes so small that it becomes useless as an input to the microcontroller.

3.4

INTERCONNECTION OF ALL THE COMPONENTS

After all the components had been tested, the connections were made according to the design of the circuit shown in Figure 3.5 which had been simulated. The infrared transmitter is driven with a +5 volts D.C power supply and the transmitter transmits infrared signals continuously. The PIC is also driven with a +5 volts D.C power supply through terminals VDD and the VSS terminals connected to ground. The emitter of the phototransistor is taken as an input to port Ra0 which is an analogue input port and the A/D converter module is used to convert the signals into its corresponding digital form. The PIC is clocked at 8MHz using a crystal oscillator through the CLKIN and CLKOUT pins of the microcontroller. The output which is used to drive the stepper motor is taken from pins RD4, RD5, RD6 and RD7 into the gate of each field effect transistor (FET). The output (i.e. the source) of the FET is then an amplified voltage used to drive the stepper motor by energizing the corresponding coil while the drain is grounded. The stepper motor is driven by a +24 volts D.C power supply.

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Figure 3.5

The Schematic Design of an Object Position Locator

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CHAPTER 4 RESULTS

4.1

PROJECT EXPECTATIONS The design was expected to be able to locate an object on the same platform

(same line-of-sight) with the receiver within a range 35 meters from the location of the receiver and align itself to the direction of position of the object. This is to be done continuously as long as the object being located is changing its location.

4.2

LIMITATIONS The design is not 100 percent perfect to perform all of its operations in all

conditions. It was observed that the design has some limitations as listed below; The design will not be able to locate any object outside the range (35 meters) of the infrared receiver. The speed of movement of the object to be located should not be greater than the speed of rotation of the stepper motor involved. In applications where the object to be located is to be tagged secretly, the tag might be removed and this will cause the design not to perform its work. The position of the transmitter should be in line-of-sight of the receiver else, the design will not perform its operations. Any blockage in the line-of-sight will make the device not functional.

4.3

RESULTS After the design and construction, testing of the device was carried out to

ascertain the working conditions of the device. The design performed the operations

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expected i.e. locate an object that has been tagged and point in the direction of location. The transmitter and the receiver have to be on the same level for the device to work and also the device works only for a distance of seven meters between the transmitter and receiver.

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CHAPTER 5 CONCLUSION AND RECOMMENDATION

5.1

CONCLUSION This project locates an object that has been tagged with an infrared transmitter

which is in the range of the receiver. The receiver upon location of the object turns the dish mounted on the stepper motor in the direction of the location of the object. It can be concluded that the device will work in it specified limits.

5.2

RECOMMENDATION The project is recommended for use in the following areas; The location of an athlete on a track. Location of objects in a perimeter within the specified range of the device.

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REFERENCES

Campbell T.D, Naik A.L., Stone R.E (2002), "Biological Infrared Imaging and Sensing". Delmar Publishing Inc.

Depp Steven (2002), Optical Fiber Communication: From Transmission to Networking, (English). IEEE

Gorbunov V. and Tsukruk S.L. (2006), "Thermal Detection of Biological Infrared Receptors". Longman Limited, London.

Lockheed S.K. (1999), Wavelength Technology Seventh Edition, Infrared Spectroscopy, Michigan State University.

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APPENDIX A1 MIKROBASIC CODE FOR THE CONTROL PROCESS

program object position locator_1_1_08 dim counter, counter2 as word dim counter3 as byte sub procedure interrupt if intcon.1 = 1 then counter = counter + 1 intcon.1 = 0 end if if pir1.0 = 1 then counter2 = counter2 + 1 pir1.0 = 0 end if end sub main: pwm_init(5000) trisb = %00000001 trisa = 255 portb = 0 pwm_change_duty(16) pwm_start adcon0 = 0 adcon1 = %00000110 intcon = %11000000 option_reg = 0

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pie1 = 1 pir1 = 0 tmr1l = $e8 tmr1h = $fd t1con = %00110001 intcon.4 = 1 while true if counter2 = 1 then intcon.4 = 0 t1con.0 = 0 if (counter >= 3) and (counter = 1) and (counter = 1) and (counter VDD)..20 mA Output clamp current, IOK (VO < 0 or VO > VDD)20 mA Maximum output current sunk by any I/O pin......................................................25 mA Maximum output current sourced by any I/O pin ................................................25 mA Maximum current sunk by PORTA, PORTB and PORTE (combined)..........................................................................200 mA Maximum current sourced by PORTA, PORTB and PORTE (combined)..................................................................................200 mA Maximum current sunk by PORTC

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and PORTD (combined)......................................................................200 mA Maximum current sourced by PORTC and PORTD (combined)......................................................................200 mA Note 1: Power dissipation is calculated as follows: PDIS = VDD x {- IOH} + {(VDD VOH) x IOH} + (VO1 x IOL) Note 2: Voltage spikes below Vss at the MCLR pin, inducing currents greater than 80 mA, may cause latch-up. Thus, a series resistor of 50-100 should be used when applying a low level to the MCLR pin rather than pulling this pin directly to Vss.

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APPENDIX A3 PHOTOTRANSISTOR (QSE114) DATASHEET

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APPENDIX A4 INFRARED LIGHT EMITTING DIODE DATASHEET

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