Project 1 - Controlling a DC motor using PWM and monitoring its Running status
PROJECT
AIM:
Implement a system on the simulator for controlling a DC motor using L293 motor driver, monitor its status and print the running status of motor on the LCD Display.
Goals:
- Implement a system on simulator for Controlling the DC motor using L293 motor driver.
- Displaying the running status of DC motor on the LCD display.
Key Highlights of the Project:
- The DC motor can be controlled by using L293 motor driver.
- The speed of a DC motor can be controlled by varying its input voltage, for doing this is to use PWM (Pulse Width Modulation).
- L293D IC is a typical Motor Driver IC which allows the DC motor to drive on any direction.
Deliverables of this project:
- Implement the system for controlling DC motor.
- Controlling the speed of the DC motor using PMW.
- Displaying the present running status of DC machine on LCD display.
DC Motor:
- A DC motor is defined as a class of electrical motors that convert direct current electrical energy into mechanical energy.
- When kept in a magnetic field, a current-carrying conductor gains torque and develops a tendency to move.
- Thus when electric fields and magnetic fields interact, a mechanical force arises.
- This is the principle on which the DC motors work.
L293 Motor Driver:
- L293d IC is known as a motor driver.
- It is a low voltage operating device like other ICs.
- The other ICs could have the same functions like L293d but they cannot provide the high voltage to the motor.
- L293d provides the continuous bidirectional Direct Current to the Motor.
- The Polarity of current can change at any time without affecting the whole IC or any other device in the circuit.
- L293d has an internal H-Bridge installed for two motors.
Code:
#include <avr/io.h> //we are using the I/O registers of AVR
#define F_CPU 16000000L // define the CPU frequency
#include "avr/interrupt.h" // we are using external interrupt pin
#include <util/delay.h> // delay function
#define sw_dir (PIND & (1<<1)) // d1 pin is declared as switch button for direction control.
#define sw_dspd (PIND & (1<<2)) // d2 pin is declared as push button for speed control.
#define pw (PINC & (1<<3)) // c3 is declared as switch button for power ON/OFF
#define lcd_port PORTB //PORTB pins are dedicated for LCD data
#define RS_high PORTD |= (1<<5) // d5 pin is used for RS
#define RS_low PORTD &=~ (1<<5)
#define EN_high PORTD |= (1<<6) // d6 pin is used for EN
#define EN_low PORTD &=~ (1<<6)
unsigned char i; //variable declared to increase the duty cycle in PWM
void lcd_cmd(char cmd) //command for lcd display
{
lcd_port = (cmd & 0xf0); // Masking 4 bits for 4 bit lcd mode
RS_low;
EN_low;
_delay_ms(1); //after 1ms disable lcd
EN_high; //enable the lcd
lcd_port = ((cmd<<4) & (0xf0)); //lcd port
RS_low;
EN_low;
_delay_ms(1); //after 1ms disable lcd
EN_high; //enable the lcd
}
void lcd_data (char data) //send the data to lcd
{
lcd_port = (data & 0xf0); // Masking 4 bits for 4 bit lcd mode
RS_high; //access data register
EN_low;
_delay_ms(1);
EN_high;
lcd_port = ((data<<4) & (0xf0)); //4 bits for 4 bit lcd mode
RS_high; //access data register
EN_low;
_delay_ms(1);
EN_high;
}
void lcd_init()
{
lcd_cmd(0x28);// used for 4 bit lcd mode
_delay_ms(5);
lcd_cmd(0x02); // return home
_delay_ms(5);
lcd_cmd(0x01); // clear screen
_delay_ms(5);
lcd_cmd(0x0C); // display on cursor off
_delay_ms(5);
lcd_cmd(0x06); // increment the display cursor
_delay_ms(5);
lcd_cmd(0x80); // force cursor to begin from 1st line
_delay_ms(5);
}
void cursorpos(char x,char y)
{
if((x<1 || x>2) || (y>16 || y<1 )) //condition will checks the 2 rows and 16 columns
{
x=1; //x= row
y=1; //y= column
}
if(x==1)
{
lcd_cmd(0x7F + y); //{ 80-1 = 7F} for starting the 1st line hex decimal value (80) we are using 7f+y as need to start from that column
}
else //(x==2)
{
lcd_cmd(0xBF + y); //{0C-1 = 0B} for starting the 2nd line, 2nd row
}
}
void lcd_out(char x, char y, char *str) //here we are checking which position we want to print
{
cursorpos(x,y);
while(*str)
{
lcd_data(*str);
str++;
}
}
int main(void)
{
DDRB = 0XFF; //Declaring all 8-pins as output
DDRA |= ((1<<0)| (1<<1)); //Declaring A0 & A1 pins as output
DDRD &=~ (1<<1); //Declaring D1 pin as input
DDRD &=~ (1<<2); //Declaring D2 pin as input
DDRD |= (1<<5); //Declaring D5 pin as output
DDRD |= (1<<6); //Declaring D6 pin as output
DDRC &=~ (1<<3); //Declaring C3 pin as input
PORTD |= (1<<2); //enabling internal pull up resistor for D2
PORTC |= (1<<3); //enabling internal pull up resistor for D3
i=64; //initializing i=64 because we are running the motor with 25% duty cycle
TCCR0=0X61; //Non-Inverting mode, PWM phase correct mode,NO prescalar
GICR=(1<<INT0); //using INT0 for interrupt
MCUCR=0X02; //make interrupt negative edge triggered
sei(); //Enable global interrupt
lcd_init(); //Initialize lcd
while(1)
{
while(pw==0) //continue till the push button is released.
{
if(sw_dir == 0) //if the direction control push button is released.
{
PORTA = 0b00000001; // 1 0 to respective 1A 2A pins to rotate in clockwise direction.
lcd_out(1,1,"Motor Running CL"); //Running clock wise direction
}
else
{
PORTA = 0b00000010; // 1 0 to respective 1A 2A pins to rotate in Anti-Clockwise direction.
lcd_out(1,1,"Motor Running ACL"); //Running Anticlock wise direction
}
OCR0 = i; //i increases in ISR, the corresponding value is to be loaded into OCR0.
}
PORTA = 0x00; // 0 0 to respective 1A 2A pins to Stop rotation.
lcd_out(1,1,"Motor is TURNOFF"); //motor is turnoff
}
}
ISR(INT0_vect) //interrupt service routine
{
i=i+20; /* as i increases the duty cycle also increases. i increases by 20 in each push
and the corresponding value is to be loaded into OCR0 in while loop*/
}
Circuit Module:
Output:
When Power Switch-Off, Direction Switch-Off,Speed Switch-Off: Motor is Turn Off Condition
When Power Switch-On, Direction Switch-Off,Speed Switch-Off: Motor is Turn On Condition and Motor is running clockwise direction
When Power Switch-On, Direction Switch-On,Speed Switch-Off: Motor is Turn Off Condition and Motor is runnig Anticlockwise direction
When Power Switch-On, Direction Switch-Off,Speed Switch-On: Motor is Turn On Condition and speed of motor is increase
When Controll the speed using speed switch, increase the speed of motor
Result:
- Thus implemented a system on simulator to control a DC motor using PMW.
- Monitoring the running status of the DC motor using L293 motor driver which allows the DC motor to drive on any direction.
- Running status i.e. on which direction the DC motor is running is to be displayed on the LCD screen.
Embedded - Live Batch 9 | LS