1. GOVERNMENT COLLEGE OF ENGINEERING, CHANDRAPUR
ELECTRICAL ENGINEERING DEPARTMENT
2014-15
ARM CORTEX ( LPC 2148 ) BASED MOTOR SPEED CONTROL
GUIDED BY-
PROF.S.P.JOLHE
PRESENTED BY
1. UDAY D. WANKAR 7. VARSHA V. HIWARE
2. GOPAL K. MOTI 8. LAKSHMI SINGH
3. PRATIK A. SAKHARKAR 9. RUPALI N. GHTUKE
4. KUNAL R. PATIL
5. SURENDRA M. BUTALE
6. VILAS J. DORLE

2. Introduction
 AC motors have been widely used for the industries since
earliest days of electrical engineering.
 The project is designed to control the speed of a DC and AC
motor using ARM7 LPC2148 processor .
 This project uses the PWM principle to control the speed of the
motor by varying the duty cycle of the pulses applied to it known
as PWM Control.
 The project uses the input button interfaced to the processor.
 A motor driver IC is interfaced to the ARM7 LPC2148 processor
board for receiving PWM Signal.

3. HARDWARE REQUIRED
 Power Supply
 LPC 2148 Development Board
 LCD
 Control switch board
 L293D Driver IC
 Optocoupler (MOC 3021)
 TRIAC BT136
 Snubber Circuit

4. Working Principle
 If voltage across motor terminal is varied, then speed can
also be varied. This project uses the above principle to
control the speed of the motor by varying the duty cycle of
the pulses applied to it, popularly known as PWM control.
 The average voltage given or the average current flowing
through the motor will change depending on the duty cycle,
ON and OFF time of the pulses, so the speed of the motor
will change.

5. Pulse Width Modulation
(PWM)
what is it?
 Output signal alternates between on and off within specified
period
 Controls power received by a device
 The voltage seen by the load is directly proportional to the
source voltage

6. Definition
 Duty Cycle: on-time / period
 Vlow is often zero
LOWHIAVG VDDVV )1( 

7. PWM signals of varying duty cycles

8. Block diagram of our system

9. Architecture of implemented
system

10. ARM LPC2148
 32 bit ARM7 microcontroller in a tiny LQFP64
package.
 40kb of on-chip RAM.
 512kb of on-chip flash memory.
 High speed 60 MHz operation.
 Two analog to digital converters(10 bit).
 Total 14 ADC inputs in LPC2148.
 6 PWM outputs.

11. Pin diagram of LPC2148

12. Control Switches
 On pressing clockwise or anticlockwise button ,LPC
configure output for clockwise or anticlockwise
direction.
 On pressing low sped or high speed button motor start
rotation in clockwise direction.

13. DC motor driver circuit
 L293D is a dual H-bridge motor driver integrated circuit
(IC).Motor drivers act as current amplifiers since they take a
low-current control signal and provide a higher-current
signal.

14. Features:
 Wide supply-voltage range:4.5V to 36V
 Separate input-logic supply
 Internal ESD protection
 Thermal shutdown
 High-Noise-Immunity input
 Output current 1A per channel(600 mA for L293D)
 Output clamp diodes for inductive Transient
Suppresion (L293D)

15. Schematic of L293D

16. AC motor driver
 Ac motor driver circuit uses optoisolator MOC3021, TRIAC
BT136 and snubber circuit. The process is carried out at high
frequency, switching load on and OFF thereby controlling power
to the load.

17. Optoisolator (MOC3021)
 Optoisolator MOC3021 is 6 pin IC & is made up of light
emitting diode and DIAC which are Electrically isolated.
 Optoisolator allows two circuit to exchange signal yet
remain electrically isolated.
 The light is proportional to the signal, so the signal is
transferred to the photodiac.
 This is the principle used in opto triac and opto SCRs
which are readily available in IC form.
 The isolation between low power and high power circuits
in this optically connected device is several thousand
volts.
 Optoisolator MOC3021 is mainly used as TRIAC driver
in this project

18. TRIAC
 TRIAC is a bidirectional triode thyristor.
 It can be triggered by either a positive or negative voltage
being applied to its gate electrode.
 TRIAC is allowing the control of very large power flows with
mA-scale control currents for ac circuit.
 Applying trigger pulse at a controllable point in a AC cycle
allows one to control the percentage of the current that flows
through TRIAC to the load.

19. Snubber circuit
 The main function of snubber circuit is to improve the
switching behavior of the TRIAC at turn off.
 It is often designed with a network made of a resistor R
and a capacitor C, the SNUBBER circuit.
 This circuit can also be used to improve TRIAC
immunity to fast transient voltages.

20. Result of DC motor Control
 PWM signals from LPC2148 is given to L293D which
controls 12V or greater voltage by 5V dc from PWM
pins.
 At 30% duty cycle PWM signals, DC motor runs at low
speed.

21.  At 90% duty cycle PWM signals, DC motor runs at high
speed.

22.  50% PWM signal is given to MOC3021, DIAC in
MOC3021 triggers triac gate only 50% of single pulse
i.e. TRIAC is on for 50% of time. AC motor runs at
lower speed.
Result of AC motor Control

23.  90% PWM signal is given to MOC3021, DIAC in
MOC3021 triggers triac gate only 90% of single pulse
i.e. TRIAC is on for 90% of time. AC motor runs at
higher speed.

24. Conclusion
1. The main aim of this project is to control the speed of motor
using PWM technique by ARM processor.
2. Implementation is easy and understandable.
3. User friendly project.