AUTOMATED IDENTIFICATION AND SECURITY SYSTEM F O R ECE LABORATORY
by
Cajita, Modesto Trexine Alguidano, Ramon Jr. A.
Soriano, Melanie Sarmiento, Julius
Abstract: The population o f ECE students o f Central Philippine University (CPU) is increasing and the s ta ff o f ECE Lab has the hard time m onitoring students who w ant to access the Lab. Laboratory teachers usually require the laboratory assistants to record the time duration the student uses the laboratory. Manual log-in and log
out is done fo r this purpose and it cannot be avoided th a t sometimes this system gives erroneous results and take up considerable time.
This paper describes our project under Engr. Cirilo C. Calibjo which is a solution to problems inherent to manual log-in and log-out procedures. The objective o f the project is to design an automated id e n tific a tio n a n d s e c u rity system usin g th e M68HC11 microcomputer u n it (MCU) o f M otorola to remedy the problem.
We developed a system which requires tw o sets o f numbers to gain access in the lab., a p ro to ty p e was made to te s t the functionality o f our design. Although actual field implementation a n d te s tin g was n o t p o ssib le, th e p ro to ty p e re s u lts w ere encouraging.
INTRODUCTION:
Laboratory classes, walk-in laboratory classes in particular, are inherent to engineering education and instructors handling laboratory classes often desire to m onitor the use of laboratory facilities. This monitoring process helps the teachers determ ine w ho among his students are actually perform ing their laboratory exercises and to answ er o th er questions about the performance of their students. To aid in m onitoring factors such as frequen cy and duration of use of laboratory facilities of students of each student, logbooks have often been
used. A lthough th is is th e least c o m p lic a te d s o lu tio n , it is n o t necessarily the most efficient. Human errors are inherent in such system and takes time specially w hen the volume of students entering and leaving the laboratory is of considerable size.
T h e a lte rn a tiv e s o lu tio n to manual log is automation. Automation is - b e s t im p le m e n te d u sin g m ic r o p ro c e s s o r s a n d m ic ro controllers. Automated log minimizes hum an error since minimal hum an intervention is required and this also speeds up the process. Automation can be im plem ented by hardw iring
individual logic gates to derive the desire output but this complicates the im p le m e n ta tio n and in tro d u c e s inflexibility to the system.
M ic ro p ro c e s s o rs and m icro controllers have evolve from simple devices such as the abacus to the complicated mechanical computers of Charles Babbage to the first electronic com puter called ENIAC and to the p re s e n t silico n-based single-chip electronic devices. M icroprocessors are VLSI (Very Large Scale Integration) chips, w hich perform s the function of a CPU (Central Processing Unit).
The m icroprocessor chosen in the implementation of the solution was the M68HC11 micro controller. This reports describes the solution and m ethod of im plem entation using the M68HC11. The project demonstrates the feasibility of using the M68I IC11 m icro contro ller in an autom ation solution and its capabilities.
General Description of M68- HG1 1:
The micro controller used in this project is the M68HC11 by Motorola.
It is usually referred to as M68HC11 Evaluation Board or EVB. The high- density com plem entary metal-oxide s e m ic o n d u c to r (HCM OS) MC68HC11A8 is an advance 8-bit MCU w ith highly sophisticated, on- chip peripheral capabilities. New desig n te c h n iq u e s w e re used to achieve a nom inal bus speed of 2 MHz. In addition, the fully static design allows operation at frequencies down to dc, fu rth er reducing pow er consum ption. The EVB requires a user supplied +5, +12, and -12 Vdc
p o w e r s u p p ly a n d an RS-232C com patible term inal for operation.
The HCMOS technology used on th e MC68HC11A8 com bines smaller size and higher speeds w ith the low p ow er and high noise immunity of CMOS. O n-chip m em ory systems in c lu d e 8K b y te s o f rea d -o n ly m e m o ry (ROM ), 512 b y te s o f electrically erasable program m able ROM (EEPROM), and 256 bytes of random-access m em ory (RAM).
Major peripheral functions are provided on-chip. An eight-channel analog-to-digital (A/D) converter is inclined w ith eight bits of resolution.
A synchronous serial communications in te r fa c e (SCI) a n d a s e p a r a te s y n c h ro n o u s s e ria l p e r ip h e r a l interface (SPI) are included. The m ain 16 -b it, fre e -ru n n in g tim e r system has three input capture lines, five output-com pare lines, and a real
tim e in te rru p t function . An 8-bit pulse accum ulator subsystem can count ex tern al events o r m easure external periods.
S elf-m o n ito rin g c ir c u itr y is include on-chip to p ro te c t against system errors. A com puter operating p rop erly (COP) w atc h d o g system protects against softw are failures. A clock m onito r system g en erates a system reset in case the clock is lost or runs too slow. An illegal op code d e te c tio n c irc u it pro v id es a n o n maskable in te rru p t if an illegal op code is detected.
To dem onstrate the capabilities of this MCU, the EVB was designed along w ith a m o n ito r/ debugging program called BUFFALO (Bit User Friendly Aid to Logical O perations).
This program is contained in EPROM
34
e x te rn a l to the MCU. T he EVB provides a low cost tool for debugging and evaluation o f M68HC11 MCU- based target system equipm ent. It is designed to o p erate in eith er th e debugging or evaluation (emulation) mode of operation.
System Overview:
The study entails designing a security system th at will act as an electronic lock that can be unlocked using num eric data. Unlike ordinary e le c tro n ic locks w e re a c o n sta n t security code is shared by those w ho are a u th o riz e d , th e system shall require each authorized user of the system to enter a security code unique to each user. The valid num eric code includes the identification num ber (ID ) an d p e rs o n a l id e n tific a tio n n u m b e r (PIN ). T he system also requires con tin u o u s p o w e r for its operation.
T h e w h o le sy ste m can b e divided into three subsystems namely the PC (personal computer), EVB, and keypad. Sensors and servom otor are also a d d e d fo r e ffic ie n t im plem entation of the system. This can be best describe w ith the aid of Figure 1.
Figure 1. Block Diagram of Autom ated Identification and S ecurity System.
The system is initiated in the Personal Computer. W hen the system softw are is executed in the personal com puter, the first thing it does is download the EVB software to the EVB and th e n co m m an d s th e EVB to execute the downloaded softw are.
The softw are executing on the EVB is th e o n e r e s p o n s ib le fo r accepting and interpreting the data from the keypad. It displays relevant m e ssa g e s, p r o m p ts , d a ta , an d inform ation on the display. It also senses the status of the door to ensure that the door is closed w hen it should be closed and open w hen and only w hen it should be open.
Operational Description:
The only way that the user can com m unicate w ith the control unit (com puter) is through th e keypad.
The circuit for the keypad is show n in Figure 2. The term keypad is applied to an array of keys, usually a small num ber of keys. In keypad, each key is associated with a particular symbol or binary value. W hen the key is pressed it generates a corresponding binary code. The keys are arranged in a matrix form. To determ ine that a key has been pressed, and to identify that key, the matrix is scanned. The m atrix is been scanned using the program , by making all the rows of the matrix logic 0 and sensing the logic values of the columns. If one or m ore columns is a zero, then one or m ore keys has b e e n pressed . To encode the key, each horizontal wire is, in turn, made logic 0 w ith all other horizontal wires logic 1.
Figure 2. S ch e m atic D iag ram of th e K eypad
W hile th e h orizontal w ire is logic 0, each of the vertical wire is examined to see w hether it is logic 0.
W hen a vertical line is logic 0, th e num ber of that line, together with the num ber of the logic 0 row, identifies the key. The rows of the key m atrix are controlled by the output port, and its colum n are sensed through th e input port.
It happens that the data needed for this operations is composed of the identification (ID) num ber and the personal identification num ber (PIN).
The first set of data to be punched on the keypad is the ID number. Through the aid of the program for the keypad, th e EVB w ill in te r p re t w h a te v e r n u m b er has b een p ressed on the keypad. Then the EVB will send this data to the computer. The com puter will com pare the ID num ber received w ith the existing data. If it finds a m atch it will notify the EVB and the EVB will pro m p t the user to enter its PIN number. The same process as discussed previously will take place.
W h e n th e ID an d PIN n u m b e r conform s w ith w hat is stored in the computer, the com puter will send a signal to the EVB to open the door.
The EVB will trigger the motor circuit.
The door will be opened and there
will be a sensor to determ ine if the door is fully opened for the user to enter. After the EVB sensed (through th e sen sor) that th e d o o r is fully opened, it will also trigger the m otor circuit to close the door.
The EVB prom pts th e user to e n te r the required co de using the display unit. Displays are provided to help the user use the keypad. LEDs with different colors are also installed to guide the user on w hat to do. The display unit consists of tw o DL14 14Ts and several indicator lights as show n in Figure 3. T he display unit can display only 8 characters at a time, lim itin g th e m ax im u m le n g th of strings of characters to be displayed to eight. Using the runnin g lights c o n c e p t c a n c ir c u m v e n t th is limitation. A string of character of any length can be displayed by scrolling it across the display. The display unit will scroll the string of characters to be displayed across th e display in batches of eight. First, it displays eight c h a r a c te r s s ta r tin g at th e firs t character. Then after a precalculated delay, it will display the next eight starting at the second character.
F ig u re 3. S c h e m a tic D ia g ra m o f th e D is p la y U n it
As stated above, the solution to the first problem in the display unit was to scroll messages of any length a c ro s s th e d isp la y u n i t ’s e ig h t- 36
c h a ra c te r o u tp u ts. This solution presents another problem of its own.
T he M 68HC11 c h ip , th e microprocessor used in the EVB, only have a limited num ber of output ports.
A scrolling display requires th at each character in the display unit can be access separately and this requires ports. O ne way to minimize port u sage is to m u ltip le x th e tw o DL14 14Ts of the display un it and connect all data and select ports in parallel. In able to access a specific character on the display unit, not only will w e have to set the select lines p ro p e rly b u t also to e n a b le and disable the proper DL1414T. This will require another port. To further save on ports, a single bit is used to select the p ro p er DL1414T instead of tw o - one for each DL1414T. This can be a c h ie v e d by u sin g th e in v e rte d enable/ disable pin of one DL1414T as the enable/ disable connection of another.
F ig u re 4 . S c h e m a tic D ia g ra m o f th e S e rv o m o to r D riv e r
The servomotor driver as shown in Figure 4 is an SCR-based system that allo w s th e EVB to c o n tr o l th e servomotor. It is controls the direction of the DC m o to r by changing the direction of the current. To allow-the cu rren t to change directions, tw o SCRs w ere used and connected in head-to-tail fashion and supplied with AC power. Although this can also be achieved by using a single triac, two SCRs were used instead to simplify the
design. It is easier to use tw o SCRs since there would tw o separate gates for control thereby eliminating the need to determ ine the instantaneous value of th e supply voltage. One problem that arose in the design is th a t th e gates of th e SCRs w ou ld alternately turn on causing the DC servom otor to rattle. To allow the gates to float w hen no triggering is applied, the SCR gates are connected to and driven by tw o PNP transistors.
W hen the transistors are off, the gate is effectively floating. The em itters of the transistors are connected to the +5VDC supply. T he basis o f th e transistors are set to +5VDC to turn off the transistors. To sw itch the transistors on, the base is driven low to ground.
A nother sensor will prom pt the EVB if the door is forced open. The EVB will also inform the com puter that there is an intruder. In this case, the intruder can be apprehended without his knowledge.
The PC is still capable of doing task other than m onitoring the status of the security system. The PC system software is designed to perform a type o f m u ltita s k in g - it c a n h a n d le requests by the EVB for verification of ID num bers and PINs and at the same, perform tasks w hich the PC operator wishes to do.
If it is desired to m onitor the access to a certain room, the system can be modified to coordinate w ith a log-in program running on the PC.
This way, the system is not lim ited by the m icrocontroller m em ory and can store variable log data in the hard d isk o f th e PC fo r th e f u tu r e reference.
Conclusion:
The prototype was implemented solely for the pu rp o se of testing the functionality of the design and no quantitative tests w ere conducted.
D uring trial ru n s, th e p ro to ty p e p e r f o r m e d s a tis fa c to rily . The following im portant results are listed in conjunction with the perform ance of the prototype.
• The design system simplifies the manual log-in and log-out and gives accurate results. It le s s e n s th e jo b o f th e monitoring staff.
• M68HC11 MCU is relatively easy to w ork w ith and have most of the essential features n e e d e d fo r a c o m p le te control system.
• M68HC11 MCU has built-in interface capability that is suitable for sensors, actuators, and comm unications, w hich makes it more flexible to any autom ation applications.
• T h e tim e c lo c k in g of M68HC11 is very accurate.
• A single port of M68HC11 can be used as eith er input or o u tp u t p o rts w h ic h th e n provides more ports for more applications.
Recommendation for Future Work:
Based on observations of the performance of the prototype, several aspects of th e solution will have to be modified because few errors are
evident. O ne o f th e erro rs w as a softw are bug w hich cam e up w hen a m uch faster PC was used other than th e one on w h ic h s o ftw a re w as developed. T he bug w as possibly rooted in the DELAY instruction of the PASCAL la n g u a g e w h ic h unexpectedly perform ed faster than intended. This caused by EVB to log and communications betw een the PC and the EVB to fail. This bug can be rem edied in tw o ways: use a slow er PC or replace the DELAY instruction w ith an interrupt-driven subroutine d ep endent on the system clock and not on PC speed.
A n o th e r s h o r tc o m in g o f th e p ro to typ e was the absence of th e feed b ack m echanism in th e d o o r system. Since there was no feedback, th e MCU had no way o f know ing w hether the door was actually closed, open, or som ew here in betw een. A f e e d b a c k m e c h a n is m m ay be in tro d u c e d or a to ta lly d iffe re n t m echanism like electrically operated m echanical locks can be used.
Some of the modifications are largely aesthetic in nature like the addition o f to n e-p ro d u cin g c irc u its in the keypad, w hich will produce a tone every tim e a key is pressed. The system may be further be modified to act as central control unit for the whole room, turning the laboratory into an “intelligent room.” It can then control the lighting, locks, and even electrical distribution in the room.
References:
M o to ro la, In c ., “M 68HC11 EVB Evaluation U ser’s M anual,”
First Edition, 1986.
Motorola, Inc., “M68HC11 Reference Manual,” Third Revision, USA, 1991
Spasov, P ., “M ic ro c o n tro lle r Technology: The 68H C 11,”
Regents/ Prentice Hall, New Jersey, 1993
Van Valkenburg, M. E., “Reference Data for Engineers: Radio, Electronics, Com puter, and C o m m u n ic a ti o n s , "E ig h t Edition, SAMS, United States of America, 1993
O’Brien, S. T. and Nameroff, S., “Turbo P ascal 7: T h e C o m p le te Reference," Osborne McGraw- Hill, 1993
39
