\documentclass[12pt,titlepage,a4paper]{article}
\usepackage{graphicx}
\begin{document}
\title {Miniature Electronic Elevator Model}
\author {G.VIVEKANANTH \\20032045 \and S.VAIDYANATHAN \\20032036 \and
S.RAMANATHAN \\20031991 \and S.SENTHIL KUMAR \\20032013}
\maketitle
\tableofcontents
\setcounter{tocdepth}{2}
\section {What this project does}
\subsection {Hardware}
The Elevator protoype was tested on a 8051 micro controller based PCB. A stepper motor was used to control the motion of the elevator. A Driver IC (L293D) was used to drive the stepper motor. A 7 segment display was indoctrined to show the present floor. 6 buttons (3 simulated to be interior to the lift and 3 exterior) was used to choose between the 3 floors of the hypothetical building. A stop button was also provided to give a delay on pressing. The physical elevator is simulated by a printer head.
\newline
Due to Hardware problems, we have provided an alternate solution by using the 8085 microprocessor kit to drive the stepper motor.
\subsection {Software}
The Software to run this project has been done for 2 main micro processors -- the Intel 8085 and Intel 8051 (microcontroller). The 8051 makes use of the internal timer clocks, while the 8085 largely depends on the delay routine to provide its timing facility.
\section {Hardware Details}
\begin {itemize}
\item Intel 8051 Micro Controller
\item L293D driver IC
\item 6 V input Supply
\item Regulator IC
\item Stepper Motor
\item 7-segment display
\item 7-segment driver
\item LCD Display
\item Keyboard
\item Buttons
\end {itemize}
\section {DataSheets and Pin Details}
\subsection {Intel 89S8252 Micro Controller (Intel 8051)}
\begin {center} \includegraphics [scale=0.6] {8051.eps} \end {center}
%\sebsection {
\subsection {L393D -- Driver IC}
\begin {center} \includegraphics [scale=0.6] {l293d.eps} \end {center}
\subsection {7805 -- Regulator IC}
\begin {center} \includegraphics [scale=0.7] {7809.eps} \end {center}
\section {Working of the Elevator}
\subsection {Main Circuit Diagram}
\begin {center}\includegraphics [scale=0.2] {main_circuit1.eps}\end
{center}
\subsection {Introduction}
Miniature Electronic Elevator Model is a simple electronic model showin
the workin of a Elevator. This model does all the basic functions of a lift in an efficient manner. The basic functions involve the call buttons to each floor and the emergency stop button. The actual prototype is modelled for 3 floors. But it can be extended to as many floors as possible , dependin on the requirement, the basic model being the same.
Let us see the important components used in the prototype model. Stepper motor and 7-segment LED are being interfaced using a micro-controller AT89S8252. The stepper motor is used for the basic up-down movement of the elevator. And the 7-segment display is used to display the floor in which the elevator is present at that instant. We need drivers for driving these components.
\subsection {Micro-Controller}
Micro-controller is used to interface all the hardware components of the
elevator and give commands of operation to the components. The micro
controller code decides what has to be done by the elevator at that
particular instant. The operation to be performed is decided by the
switch which is controlled by the user. The micro-controller plays the
most important role in the prototype because this only controls all the
components connected to the model. In this model, the micro-controller
controls the stepper motor and the 7-segment display which are the
hardware components in this prototype model.
\subsection { Stepper Motor}
The Stepper motor is used for the up-down movement of the
elevator. Stepper motor can be rotated using the micro controller by
givin a set of sequences in some prescribed order. By changing the
order, we can change the direction of the rotation. The speed of the
motor can also be changed by changing the speed with which the sequence
is changed by the micro-controller. The sequence for the rotation of the stepper motor in the clockwise direction is given in the table1
\begin{tabular}{c|c|c}
1 & 0 & 0 & 0 \\
0 & 1 & 0 & 0 \\
0 & 0 & 1 & 0 \\
0 & 0 & 0 & 1 \\
\end{tabular}
The sequence for the rotation of the stepper motor in the
Anti-Clockwise direction is given in Table 2
\begin{tabular}{ccc}
1 & 0 & 0 & 0 \\
0 & 1 & 0 & 0 \\
0 & 0 & 1 & 0 \\
0 & 0 & 0 & 1 \\
\end{tabular}
Thus depending on whether the elevator has to move upward or downward,
the stepper motor is designated to rotate either in the clockwise or
anti-clockwise direction. The time for which the stepper motor is to be
driven depends on the distance between the floors. Thus the stepper
motor plays an important role in the movement of the Elevator. The
stepper motor cannot be directly driven by the micro controller. It
needs a motor driver to do this job which is connected between the
controller and the stepper motor. The driver used is L293D .
\subsection {7-Segment LED Display}
The 7-segment display is used to display the floor in which the elevator is being placed at the present instant. The model is designed with three floors and they are named as Ground floor ( 0 ) , First floor ( 1 ) , Second floor ( 2 ) . Depending on the position of the lift , the corresponding number is displayed by the display. The number to be displayed is sensed by the micro controller
and commands are sent to the display to display the corresponding number. The display cannot be directly connected to the micro controller. It needs a driver between the controller and the display so that the controller drives the display.
The driver used is 7447 in our prototype.
\subsection {Circuit Description}
\subsubsection {Power Supply}
All the Ics used in our prototype require 5V power supply. This 5V
stable power supply is produced by 7805. The input to this can be any
voltage greater than 5V and the output will always be a stable 5V output
which is connected to the Vcc of all the IC.
\subsubsection {Stepper Motor}
Now let us see the full circuit description of the protoype. The pin 40
which is Vcc is connected to the 5V supply and 20 is connected to the
ground.Pin number 31 which is EA/VPP is connected to Vcc for our
purpose. PORT 1 is used for the stepper motor purpose. The pins P1.4 ,
P1.5 , P1.6 , P1.7 are used to produce the sequence for the stepper
motor. They has to be connected to the driver which is L293D. These are
connected to the 4 inputs of the driver IC as shown in the circuit
diagram. The driver IC has 2 voltages. One is Vss which is used to
activate the IC and is given 5V. The other is Vs which is the motor
voltage and 15V is given to this voltage supply.There are 4 grounds
which are interconnected and connected to the common ground. There are 2
enables namely Enable1 and Enable2. Both are connected to Vcc for our
purpose. The corresponding 4 outputs are connected to the stepper motor
4 coils to produce the required sequence. Thus the step motos has been
interfaced properly using the controller
\subsubsection {Display}
Next we have to see how to interface the display. For the display
purpose , we use PORT0. The pins used are P0.0 , P0.1 , P0.2 ,
P0.3. These pins are connected to the inputs A,B,C,D of 7447 which is a
binary to 7-segment converter. The binary number is given in the inputs
and the output of the driver contains segment output. This can be
connected to the 7-segment display . WE use common anode type fpr pur
purpose. The pin numbers to which the output of the driver are connected
are shown in the circuit diagram. Depending on which number to be
displayed , the corresponding binary number is sent from the controller
to driver which converts into it 7-segment number. Thus the required
number is being displayed usin the driver and 7-segment display.
\subsubsection {Switch Control}
The action to be performed by the elevator is basically defined by the
user through switch control. The Port used for switch action is
PORT2. The pins being used for this purpose are P2.2 , P2.3 , P2.4 ,
P2.5 , P2.6 , P2.7. The switches are directly connected to these
pins. The six switches used are Call buttons. One set is interior call
buttons for floors 0 , 1 , 2. The other set are exterior call buttons
which would be placed in each floor. Now when a switch is pressed by the
user , this is detected by the micro controller and the required action
is carried out by the micro-controller and the required commands are
sent to the stepper motor and display circuit. Thus the required action
is performed by the Miniature Electronic Elevator Model as per the user
requirement.
Thus the circuit of Miniature Electronic Elevator Model is explained
with corresponding interfacing components explained at each stage.
\section {Working of LCD Display}
\subsection {LCD Interfacing Circuit}
\begin{center}\includegraphics{CKT1.eps}\end{center}
\subsection{LCD Interfacing}
This circuit is to interface a liquid crystal display with a micro controller and display the desired in it. Here we use 2*16 display of lcds. Information on liquid crystal displays can be viewed properly only if we view it at an angle of ninety degrees.
\subsection {Description}
The 2*16 display of lcds have 14 pins which comprises of:
\begin {itemize}
\item 8 data lines
\item RS(register select)
\item R/W(read/write)
\item E(enable)
\item Vcc
\item Vee
\item GND
\end {itemize}
\subsection {Data Lines}
The data lines are used to transfer the data to and from the micro controller,8 bits at a time. In this the line D7 is used as a an intial flag signal by the lcd when RS=0 and R/W=1,which when high is indicative that the lcd is busy. Hence called the busy flag.
\subsection {Control Signals}
RS(register select)
This is used to select either the command or the data register of the liquid crystal display. When RS=0 then the command register is selected and when RS=1 the data register is selected when the user sending the ascii value of the data to be displayed is sent and displayed in the lcd
R/W(read/write)
This is decide whether we need to read from or write to the liquid crystal display.
When R/W=0 then we are writing and when R/W=1 then we are reading.
E(enable)
The lcd has an internal latch which is necessary in order to prevent the microcontroller from being loaded due to current requirement of the lcd. When we are writing we need to send to high-to-low signal so that the signal is latched into the lcd. And when we are reading a low-to-high signal is required in order that the data is obtained from the latch
\subsection {Vcc,Vss,GND}
The lcd requires +3V or +5V to work and the ground pin should be the same as that for the micro controller. The Vss pin is actually a contrast controller. A potentiometer between the source and this pin controls the contrast of the lcd.
\section {Cost Estimate}
74LS47 - Rs.20
resistors - Rs.40
capacitors - Rs.40
printer head - Rs.150
PCB - Rs.50
RNC connectors- Rs.80
LCD - Rs.160
7 segmnent LED- Rs.10
keyboard - Rs.30
-------
total - Rs.960
-------
\section{ACKNOWLEDGEMENT}
---------------
We hereby express our sincere thanks and gratitude to our lecturer
Mr.N.Ramadoss, for bringing out the creativity in us and motivating us
to do an useful prototype project. We also thank him for extending his
support all through the project which helped us to succeed in our
endeavour.
\section{8051 Code Segment}
\begin{verbatim}
org 0h
ljmp new
org 0003h
ljmp stop;
org 000Bh
mov r7,#01h
clr tr0
reti
;org 0013h
;ljmp main
org 0200h
new:
mov ie,#86h
setb ip.1
;here:sjmp here
ljmp main
org 0030h
main:
mov r0,#01h
mov r1,#01h
mov r7,#00h
mov p0,#00000011b
keys: mov p2,#0ffh
mov a,p2
cjne a,#0feh,xkey0
jmp key0
xkey0:mov a,p2
cjne a,#0fdh,xkey1
jmp key1
xkey1:mov a,p2
cjne a,#0fbh,xkey2
jmp key2
xkey2:mov a,p2
cjne a,#0f7h,xkey3
jmp key3
xkey3:mov a,p2
cjne a,#0efh,xkey4
jmp key4
xkey4:mov a,p2
cjne a,#0dfh,xkey5
jmp key5
xkey5:sjmp keys
key0:
cjne r0,#01h,key01
ljmp keys
key01:
cjne r0,#03h,key02
dec r0
dec r0
ljmp mot
key02:
dec r0
ljmp mot
key1:
cjne r0,#02h,key11
ljmp keys
key11:
cjne r0,#03h,key12
dec r0
ljmp mot
key12:
inc r0
ljmp mot
key2:
cjne r0,#03h,key21
ljmp keys
key21:
cjne r0,#02h,key22
inc r0
ljmp mot
key22:
inc r0
inc r0
ljmp mot
key3:
cjne r0,#01h,key31
ljmp keys
key31:
cjne r0,#03h,key32
dec r0
dec r0
ljmp mot
key32:
dec r0
ljmp mot
key4:
cjne r0,#02h,key41
ljmp keys
key41:
cjne r0,#03h,key42
dec r0
ljmp mot
key42:
inc r0
ljmp mot
key5:
cjne r0,#03h,key51
ljmp keys
key51:
cjne r0,#02h,key52
inc r0
ljmp mot
key52:
inc r0
inc r0
ljmp mot
stop:
mov r3,#0ffh
l1: mov r4,#0ffh
l2: djnz r4,l1
djnz r3,l2
reti
mot:
mov r7,#00h
mov a,r0
clr c
subb a,r1
cjne a,#01h,motup2
setb p3.6
mov r2,#7fh
mov a,#88h
nlp:
mov tmod,#01h
mov tl0,#00h
mov th0,#00h
;mov ie,#82h
setb tr0
here0:
clr p3.6
mov p1,a
mov r5,#0ffh
la1: mov r6,#0cch
delaay:djnz r6,delaay
djnz r5,la1
rr a
setb p3.6
cjne r7,#01h,here0
djnz r2,nlp
mov 01,00
mov r7,#00h
clr p3.6
ljmp led
motup2:
cjne a,#02h,motdown1
setb p3.6
mov r2,#0ffh
mov a,#88h
nlp1:
mov tmod,#01h
mov tl0,#00h
mov th0,#00h
;mov ie,#82h
setb tr0
here1:
clr p3.6
mov p1,a
mov r5,#0ffh
lb1: mov r6,#0cch
delayb:djnz r6,delayb
djnz r5,lb1
rr a
setb p3.6
cjne r7,#01h,here1
djnz r2,nlp1
mov 01,00
mov r7,#00h
clr p3.6
ljmp led
motdown1:
cjne a,#0ffh,motdown2
setb p3.7
mov r2,#07fh
mov a,#11h
nlp2:
mov tmod,#01h
mov tl0,#00h
mov th0,#00h
;mov ie,#82h
setb tr0
here2:
clr p3.7
mov p1,a
mov r5,#0ffh
lc1: mov r6,#0cch
delayc:djnz r6,delayc
djnz r5,lc1
rl a
setb p3.7
cjne r7,#01h,here2
djnz r2,nlp2
mov 01,00
mov r7,#00h
clr p3.7
ljmp led
motdown2:
setb p3.7
mov r2,#0ffh
mov a,#11h
nlp3:
mov tmod,#01h
mov tl0,#00h
mov th0,#00h
;mov ie,#82h
setb tr0
here3:
clr p3.7
mov p1,a
mov r5,#0ffh
ld1: mov r6,#0cch
delayd:djnz r6,delayd
djnz r5,ld1
rl a
setb p3.7
cjne r7,#01h,here3
djnz r2,nlp3
mov 01,00
mov r7,#00h
clr p3.7
ljmp led
led:
cjne r1,#01h,floor2
mov p0,#00000000b
ljmp keys
floor2:
cjne r1,#02h,floor3
mov p0,#10000000b
ljmp keys
floor3:
mov p0,#01000000b
ljmp keys
end
\end{verbatim}
\end{document}