bidirectional report

Bi-Directional Motor
EMP - Department
Submitted :Abdullah Amin 6/24/16 SIP- 16

1 | P a g e
Group Members:
 Hasan Iqbal Baig
 M Noraiz
 Muneer Ahmad
 Waqar Shaukat
 Amir Saleem

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Contents
Abstract:...................................................................................................................................................................................3
Introduction: ..........................................................................................................................................................................4
Background: ...........................................................................................................................................................................4
H-bridge:.............................................................................................................................................................................6
Logic toggle:......................................................................................................................................................................7
Procedure:...............................................................................................................................................................................7
Flow Chart:.......................................................................................................................................................................10
Results:...................................................................................................................................................................................11
Conclusion: ...........................................................................................................................................................................13
References: ...........................................................................................................................................................................13
Appendix:..............................................................................................................................................................................14

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Abstract:
This report deals with the working of the bi-directional motor working and the implementation of it. The
task was to show the duty cycle with the three speeds and time on the LCD. The coding of the report
is shown in the appendix while the results shows the complete working of it in both the directions.
Hence this report also covers the aspect of working of H-bridge and toggle circuit.

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Introduction:
A micro-controller is defined as a small stand-alone computer, which is capable of executing
commands in series as well as parallel. It perform pre-programmed tasks and interacts with other
hardware devices. Being packed, in a tiny integrated circuit (IC) whose size and weight is usually
negligible, it is becoming the perfect controller for robots or any machines to perform some kind of
intelligent automation. A single microcontroller can be sufficient to control a small mobile robot, an
automatic washer machine or a security system. Apart from this, a microcontroller also possesses a
memory place to store the program which is to be executed, and a number of input/output lines that
are used to interact with other devices.
Microcontrollers are so cheap and easily available that now-a-days it is used to simplify logic circuits
with a sole purpose of attaining some design flexibility and saving memory. Apart from that, some
machines and robots even relies on a number of microcontrollers, each microcontroller is asked to
perform a certain task. Most recent microcontrollers are ‘In System Programmable’, means in it, you
can modify the program which is to be executed, without removing the microcontroller from its place.
Background:
Microcontroller is different from microprocessor because microcontroller has internally linked input
output ports and memory storage elements like register, timer etc. In microprocessor we have to
configure all inputs outputs and memory storage elements externally. Microcontroller is cheaper than
microprocessor.
Block diagram of microcontroller is shown in fig
[1]
Figure 1 Block Diagram Of Microcontroller
It consists of four input as well as four output ports like port 0, port 1, port 2 and port 3. All ports have
8 pins which can be represented by p0.1, p0.2 etc. We can configure all inputs pin as output pin by
initializing all pins with zero and can also use all pins one by one as input or output.

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As you can see there are two types of memories; one is RAM and other one is EEPROM flash. Ram
is used during programme execution for storage of variable for short time and EEPROM is used for
writing the programme.
The internal memory of 8051 microcontroller has 4kb ROM and 128 Byte Ram. Whereas, the internal
memory contains 128 bytes of RAM i-e 00h and 7 Eh. The Ram is divided into three parts:
 4 Rag bank ooh to 1Fh
 16 bytes bit addressable RAM 20h to 2Fh
 Scratch pad RAM
Similarly, the register Bank has four registers, which each bank carrying eight registers.
 bank 0=Ro to R7
 bank 1= Ro to R7
 bank 2= Ro to R7
 bank 3= Ro to R7[2]
[2]
Figure 2 Pin configuration of 8051
After understanding the micrcontroller working, lets discuss the working of DC motor as well.
A DC Motor is an electrical machine which converts electrical energy into mechanical energy. It needs
5 to 12 volts to run its speed which is directly proportional to the applied voltage.

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[3]
Figure 3 DC Motor.
The input of a DC motor is current/voltage and its output is torque (speed). The working of DC motor
is explained below:
The piece connected to the ground is called the stator and the piece connected to the output shaft is
called the rotor. The inputs of the motor are connected with two wires and by applying a voltage across
them, the motor rotates. The torque of a motor is generated by a current carrying conductor in a
magnetic field. The right hand rule states that if you point your right hand fingers along the direction of
current, I, and curl them towards the direction of the magnetic flux, B, the direction of force is along the
thumb.
[4]
Figure 4 DC Motor Working
H-bridge:
L293D is basically H-bridge IC. It is used for deriving the motor. It can drive the motor in both
clockwise and counter clockwise direction. Basically it is an electronic that enables a voltage to be
applied across a load in either direction.

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For making the H-bridge, we use the series of relays from relay board. A solid state H bridge is
typically constructed using opposite polarity devices, such as PNP BJTs or P-
channel MOSFETS connected to the high voltage bus and NPN BJTs or N-channel MOSFETs
connected to the low voltage bus.
A common use of the H-bridge is an inverter. The arrangement is sometimes known as a single-
phase bridge inverter.
The H-bridge with a DC supply will generate a square wave voltage waveform across the load. For a
purely inductive load, the current waveform would be a triangle wave, with its peak depending on the
inductance, switching frequency, and input voltage.
[5]
Figure 5 H-bridge Pin Configuration
Logic toggle:
Logic toggle is used as a switch for on and off. We used all these as a switch. On logic toggle there 1
shows to 5V and zero shows to zero volt.
Procedure:
In this project we have to use 8051 for controlling speed of bidirectional motor .We have to show three
different speeds on LCD and we have to drive motor in clockwise as well as anticlockwise direction.
First of all we are using H-bridge with the microcontroller attached. The H-bridge is used to rotate the
motor in both directions i-e CW and CCW.

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[6]
Figure 6 H-bridge Working
When we apply voltage on forward input i.e. by giving 1 through logic state then transistor Q-1 and Q-
3 on and transistor Q-2 and Q-4 off and motor will move in clockwise direction.
Similarly in case of reverse input when we apply voltage on reverse input i.e. by giving 1 through logic
state resulting the motor will move in anticlockwise direction and transistor Q-2 and Q-4 on and
transistor Q-1 and Q-3 off.
But in third case we come to assume that when we apply voltage in both directions i.e. by setting bit
high through logic state. Eventually the motor will turn off because we are applying the same voltages
in both directions hence resulting it cancels the effect and there is no difference of voltage being
created hence the motor will turn off.
[7]
Figure 7 H-bridge Topology
Logic toggle provides two bits i-e 0 and 1 for ON/OFF and works as a switch. Three logic toggles are
used for three different speed, one logic toggles is used to invert the direction of speed i-e to move
the motor in CW and CCW.
 Logic toggle 1 --------------- 100% speed and duty-cycle.
 Logic toggle 2 --------------- 50% speed and duty-cycle
 Logic toggle 3 --------------- 10% speed and duty-cycle
 Logic toggle 4--------------- CW/CCW direction.

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In order to accomplish that we used 16× 2 LCD for displaying the speed of the motor in CW and
CCW. First of all, we interfaced the LCD with microcontroller 8051 displaying “WELCOME TO PEL’’
on LCD and then clear the screen right after. After this, we displayed the “BIDIRECTIONAL MOTOR’’
and clear the screen. Now after this we display speed duty cycle and direction on LCD.
First of all, we placed a microcontroller 8051 in the centre. We then added the LCD along
with the H-bridge IC with the microcontroller. The DC motor is also attached as it should
rotate in both directions. Hence in order to do that, four switches are added with the
microcontroller and combination of it is controlling the whole circuit. When the fourth switch
is pressed, the motor rotates in opposite direction. The direction and working of motor is
basically controlled with the help of H-bridge which is explained earlier. The flow chart is
explained below:

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Flow Chart:
Welcome to PEL
When Switch 1 is
active high,
SPD, DCYCLE = 100%
CW
Bi-Directional
Motor
When Switch 2 is
active high,
SPD, DCYCLE = 50%
CW
When Switch 3 is
active high,
SPD, DCYCLE = 10%
CW
When Switch 1 is
active high,
SPD, DCYCLE = 100%
CCW
When Switch 2 is
active high,
SPD, DCYCLE = 50%
CCW
When Switch 3 is
active high,
SPD, DCYCLE = 10%
CCW
Otherwise
SPD, DCYCLE = 0%
STOP
Enable = 0Enable = 1

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Results:
The results comprises of the motor moving in CW and CCW direction at 100%, 50% and 10%. The
motor also moves at 10% as well which can be tested in Proteus 8. The code of the circuit is provided
in the appendix.
Figure 8 Duty Cycle 100% CW
Similarly at 50%, the circuit looks like this:

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Similarly for 10%, the circuit looks like this:
Similarly, the motor also moves in the bi-directional motor which is also shown below:
Figure 11 Duty Cycle 100% CCW

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Last but not the least, the motor moving with 50% duty cycle is represented by:
Figure 12 Duty Cycle 50% CCW
Conclusion:
Thus making long story short, this report provides the basic understanding of the working of the bi-
directional motor. Moreover it also helps to understand the working of microcontrollers which is quite
essential in the industry. So summarising it, it was a healthy session with great experience and a lot of
learning.
References:
[1]2016. [Online]. Available: http://www.keil.com/dd/docs/datashts/atmel/at89s51_ds.pdf.
[Accessed: 24- Jun- 2016].
[2]S. patel, "8051 microcontroller Block diagram and pin diagram of 8051 microcontroller with
description. | 8051 Microcontroller", Microcontrollergarden.blogspot.com, 2016. [Online]. Available:
https://microcontrollergarden.blogspot.com/2013/08/block-diagram-and-pin-diagram-of-
8051.html. [Accessed: 24- Jun- 2016].
[3]"DC Motor Control using AVR MCUs - eXtreme Electronics", eXtreme Electronics, 2008. [Online].
Available: http://extremeelectronics.co.in/avr-tutorials/dc-motor-control/. [Accessed: 24- Jun-
2016].
[4]"Theory on DC motors", Mechatronics.mech.northwestern.edu, 2016. [Online]. Available:
http://mechatronics.mech.northwestern.edu/design_ref/actuators/motor_theory.html. [Accessed:
24- Jun- 2016].

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[5]L. IC and M. Gaber, "EEEC Blog: L293D Motor Driver IC", Eeec2.blogspot.com, 2012. [Online].
Available: http://eeec2.blogspot.com/2012/11/l293d-motor-driver-ic.html. [Accessed: 24- Jun-
2016].
[6]"H Bridge with 4 NPN transistors (tip3055) using a 12v | Electronics and Electrical Engineering
Design Forum | EEWeb Community", Eeweb.com, 2016. [Online]. Available:
https://www.eeweb.com/electronics-forum/h-bridge-with-4-npn-transistors-tip3055-using-a-12v.
[Accessed: 24- Jun- 2016].
[7]"Spring2012 Final Report-Jingjing & Liye - Robotic Mobile Chair", Wiki.cs.mtholyoke.edu, 2016.
[Online]. Available:
http://wiki.cs.mtholyoke.edu/mediawiki/rmc/index.php/Spring2012_Final_Report-
Jingjing_%26_Liye. [Accessed: 24- Jun- 2016].
Appendix:
ACALL DISPLAYLCD
;.......................................BI DIRECTIONAL MOTOR.........
MOV A, #01H ; CLR SCREEN
ACALL Comwrt ; write command
ACALL Delay ; wait for LCD
MOV A, #'B' ; display B
ACALL Datwrt ; write data
MOV A, #'I' ; display I
MOV A, #'D' ; display D

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MOV A, #'I' ; display I
MOV A, #'R' ; display R
MOV A, #'E' ; display E
MOV A, #'C' ; display O
MOV A, #'T' ; display T
MOV A, #'I' ; display O

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MOV A, #'O' ; display O
MOV A, #'N' ; display O
MOV A, #'A' ; display A
MOV A, #'L' ; display L
MOV A, #0C1H; 2nd line position 1
MOV A, #'M' ; display M
ACALL Delay ; wait fo

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MOV A, #'R' ; display R
ACALL DELAY
ACALL DELAY
ACALL DELAY
;......................................... MOTOR CODE ....................
SETB P2.5 ; ENABLE THE PIN OF L293D IC
MOV P1,#00H ;CONFIGURE AS INPUT PORT
AGAIN:
MOV A,P1
CJNE A,#01,SPD1 ;FOR COMPARISON
SETB P2.3 ; FOR DRIVING THE MOTOR IN CLOCKWISE DIRECTION 100%
speed
CLR P2.4
ACALL DISPLAY1 ; FOR DISPLAY THE SPEED AND DUTY CYCLE
ACALL PERCENTAGE1 ;
ACALL DIRECTION1 ; FOR DIRECTION of motor

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SJMP AGAIN
SPD1:
CJNE A,#02,SPD2 for 2nd speed
MOV TMOD,#01H ;Load TMOD
MOV TL0, #00H ;Load low byte
MOV TH0, #0FFH ;Load high byte
CPL P2.3 ; for driving motor for 50% speed
CLR P2.4
SETB TR0 ;Start Timer 0
again1: JNB TF0, again1 ;Check TF flag
CLR TR0 ;Stop Timer 0
CLR TF0 ;Clear TF flag
ACALL DISPLAY1
ACALL PERCENTAGE2
ACALL DIRECTION1
SJMP AGAIN
SPD2: ;for driving the motor 10% speed
CJNE A,#04,SPD3 ; speed
MOV TH0, #00H ;Load high byte
SETB P2.3
CLR P2.4 ;Toggle P1.5

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MOV TL0, #0FH ;Load low byte
CLR P2.3
ACALL DISPLAY1
ACALL PERCENTAGE3
ACALL DIRECTION1
SJMP AGAIN
;..................FOR COUNTER CLOCKWISE DIRECTON.............
SPD3:

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CJNE A,#09,SPD4 ;for 100% speed and duty cycle
SETB P2.4
CLR P2.3
ACALL DISPLAY1
ACALL PERCENTAGE1
ACALL DIRECTION2
SJMP AGAIN
SPD4:
CJNE A,#10,SPD5 ;for 50% speed of motor
CPL P2.4
ACALL DISPLAY1
ACALL PERCENTAGE2
ACALL DIRECTION2
LJMP AGAIN

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SPD5:
CJNE A,#12,SPD6 ; for 10 % speed of motor
MOV TH0, #00H ;Load high byte
SETB P2.4
MOV TL0, #0FH ;Load low byte
CLR P2.3
ACALL DISPLAY1
ACALL PERCENTAGE3
ACALL DIRECTION2
LJMP AGAIN

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;.............................................................
SPD6:
CLR P2.3 ; for stopping the motor clear the both ports
CLR P2.4
ACALL DISPLAY1
ACALL PERCENTAGE4
ACALL DIRECTION3
LJMP AGAIN
;..........................................MOTOR CODE ENDING............
Delay: MOV R3, #50
Here2: MOV R4, #255
Here: DJNZ R4, Here
DJNZ R3, Here2
RET
COMWRT: MOV P0, A ; write to Port 1
CLR P2.0 ; RS = 0
CLR P2.1 ; R/W* = 0
SETB P2.2 ; E = 1
ACALL Delay ; wait for tds ns
CLR P2.2 ; E = 0

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RET
DATWRT: MOV P0, A ; write to Port 1
SETB P2.0 ; RS = 1
CLR P2.1 ; R/W* = 0
SETB P2.2 ; E = 1
ACALL Delay ; wait for tds ns
CLR P2.2 ; E = 0
RET
DISPLAY1:
MOV A, #01H ; for CLEAR SCREEN
MOV A, #'S' ; display S
MOV A, #'P' ; display P
MOV A, #',' ; display

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MOV A, #'C' ; display C
MOV A, #'Y' ; display Y
MOV A, #'C' ; display O

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MOV A, #'=' ; display =
RET
PERCENTAGE1:
MOV A, #'1' ; display 1
MOV A, #'0' ; display O
MOV A, #'+%' ; display %
RET
PERCENTAGE2:

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MOV A, #'%' ; display %
RET
PERCENTAGE3:

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RET
PERCENTAGE4:
RET
DIRECTION1:
MOV A, #0C1H ; for 2nd line position 1

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MOV A, #'W' ; display W
RET
DIRECTION2:
RET
DIRECTION3:

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MOV A, #'S' ; display S
MOV A, #'T' ; display O
RET
DISPLAYLCD:
MOV A, #38H ; LCD 2 lines 5x7 matrix
MOV A, #0EH ; Display on, Cursor on
MOV A, #01 ; clear LCD
MOV A, #06 ; shift cursor right

30 | P a g e
MOV A, #81H ; cursor at line 1, pos. 4
;.....................................PEL.......
MOV A, #'M' ; display M
MOV A, #' ' ; display

31 | P a g e
MOV A, #' ' ; display
MOV A, #0C1H; cursor at line 1, pos. 4
RET

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