There are
different methods of controlling DC motor . In this blog we will see how to
control DC Motor using Arduino Programming and L298 Motor Driver.
Brief Overview :
There are
different types of motors eg : AC motors
and DC Motors. Among those DC motor is most common and famous for Electrical
DIY projects and Hobbyist. As working of
DC motor is very simple .Connecting positive and negative terminals of
battery to DC motor would make motor will start rotating.
If we reverse the
polarity of motor by switching the leads, the motor will rotate in reverse direction.
Pulse Width
Modulation method is used to control the speed of DC Motor. In this method we
control the voltage applied to the DC motor . The increase or decrease in
voltage will increase or decrease the rotation speed of DC Motor.
Pulse Width Modulation Control of DC motor :
In Pulse Width
Modulation ,the average voltage is controlled by varying the switching
frequency . Switching Frequency is the rate at which turn on and off the power
applied to control the motor. The Switching Frequency is in order of few kilo Hertz.
So here comes the
new term “Duty Cycle”. So duty cycle indicates the “on time” when the PWM signal is high . Duty Cycle = Signal on
time + Signal of time
Duty cycles may be
expressed in perentage 10%, 40% ,50% ,90% and 100 % .
Average voltage according to Duty Cycles in
Percentages(%):
In this way by
controlling the duty cycle we can control the average voltage applied to the DC
Motor. So to apply the voltage to motor
we use the application of MOSFET (metal-oxide semiconductor field-effect
transistor). MOSFET has high switching frequency. PWM signals are given to Gate
terminal of MOSFET using Arduino depending on the PWM Signal duty cycle the
average voltage varies which in turn varies the speed of the DC Motor.
The circuit
shown below gives detail idea of circuit wiring for Arduino and DC motor:
Arduino is
programmed to vary the speed of DC motor by varying duty cycle of PWM signal.
Arduino Code :
#------------------------------------------------------------------------------------------------#
int PWMPin = 10;
int motorSpeed = 0
void setup()
{
}
void loop()
{
for (motorSpeed = 0 ; motorSpeed <= 255;
motorSpeed += 10)
{
analogWrite(PWMPin, motorSpeed);
delay(30);
}
for (motorSpeed = 255 ; motorSpeed >= 0;
motorSpeed -= 10)
{
analogWrite(PWMPin, motorSpeed);
delay(30);
}
}
#------------------------------------------------------------------------------------------------#
Direction control of DC motor using H-Bridge:
An H-Bridge is a simple electronic circuit
consisting of 4 switches allowing to select the direction of current flowing
through a part. H-Bridge consists of four manually controlled switches (BJT or MOSFET).
The name is derived from the circuit diagram which looks like a capital H connection consisting of four transistors
and a motor in the center.
H-Bridge
connection using four transistors and a motor is shown below. By switching two transistors
at the same time, we can control the flow of current i.e “Current Direction” through the motor and
hence the direction of rotation.
H-Bridge Connection Circuit :
The two control
signals A and B in the above circuit will determine the direction of rotation
of the motor. If signal A is LOW and signal B is HIGH, transistors Q1 and Q4
will be turned on and allow current to flow through the motor in a clockwise direction.
If the control signal
A is made HIGH and signal B is LOW, then transistors Q2 and Q3 will turn on and
the flow of current through the motor is reversed and so the direction of the
rotation is counter clockwise.
With the help both
the features i.e. PWM technique for DC Motor speed control and H-Bridge Circuit
for direction control, we can control speed as well as direction of DC Motor.
It is complicated
to use transistors for making an simple H-Bridge connection. For this reason,
there are dedicated H-Bridge Motor Driver IC available and common of the IC’s are L293D and L298N.
For this project,
we will use L298N Motor Driver and see DC Motor Control using L298N Motor
Driver using PWM technique with Arduino.
L298N Motor Driver :
The L298N driver is a dual H-Bridge motor driver
which allows speed control and direction
control of two DC motors at the same time. The module can drive DC motors that
have voltages between 5 and 35V, with a peak current up to 2A.
L298N module has two terminal blocks for the motor
A and motor B, and another screw terminal block for the Ground pin, the VCC for
motor and a 5V pin which can either be an input or output.
This depends on the voltage used at the motors
VCC. The module have an on board 5V regulator which is either enabled or
disabled using a jumper. If the motor supply voltage is up to 12V we can enable
the 5V regulator and the 5V pin can be used as output, for example for powering
our Arduino board. But if the motor voltage is greater than 12V we must
disconnect the jumper because those voltages will cause damage to the on board
5V regulator. In this case the 5V pin will be used as input as we need connect
it to a 5V power supply in order the IC to work properly.
We can note here that this IC makes a voltage drop
of about 2V. So for example, if we use a 12V power supply, the voltage at
motors terminals will be about 10V, which means that we won’t be able to get
the maximum speed out of our 12V DC motor.
DC Motor Control using L298N Motor driver and
Arduino :
We will see the speed control and direction control of a
DC Motor using Arduino and L298N IC. We need few additional parts for this
project and the list of parts is given below.
We will control the speed as wells as direction of
DC Motor using PWM Signal and L298N (H-Bridge).
Circuit Diagram:
Components Required :
• Arduino
UNO Board
• L298N
Motor Driver Module
• 12V
DC Motor
• 100KΩ
Potentiometer
• Push
Button
• 12V
Power Supply
• Breadboard
• Connecting
Wires
Arduino Code :
#------------------------------------------------------------------------------------------------#
int mot1 = 8;
int mot2 = 9;
int en1 = 10;
int dir = 6;
bool state = true;
int nob = A0;
int val=0;
void setup()
{
pinMode(mot1,OUTPUT);
pinMode(mot2,OUTPUT);
pinMode(en1,OUTPUT);
pinMode(dir,INPUT_PULLUP);
}
void loop()
{
val =
analogRead(nob);
analogWrite(en1, val / 4);
if(digitalRead(dir)==LOW)
{
state=!state;
while(dir==LOW);
delay(300);
}
if(state)
{
digitalWrite(mot1,HIGH);
digitalWrite(mot2,LOW);
}
else
{
digitalWrite(mot1,LOW);
digitalWrite(mot2,HIGH);
}
}
#------------------------------------------------------------------------------------------------#
