Project #1

Aim:

To implement a simulation for Control a DC motor using PWM with L293 and monitoring its Running status by using LCD.

16x2 LCD

Introduction for LCD interfacing with Atmega32

LCDs (Liquid Crystal Displays) are used for displaying status or parameters in embedded systems.

LCD 16x2 is a 16 pin device which has 8 data pins (D0-D7) and 3 control pins (RS, RW, EN). The remaining 5 pins are for supply and backlight for the LCD.

The control pins help us configure the LCD in command mode or data mode. They also help configure read mode or write mode and also when to read or write.

LCD 16x2 can be used in 4-bit mode or 8-bit mode depending on the requirement of the application. In order to use it, we need to send certain commands to the LCD in command mode and once the LCD is configured according to our need, we can send the required data in data mode.

4 Bit Mode

• In 4-bit mode, data/command is sent in a 4-bit (nibble) format.
• To do this 1st send a Higher 4-bit and then send a lower 4-bit of data/command.
• Only 4 data (D4 - D7) pins of 16x2 of LCD are connected to the microcontroller and other control pins RS (Register select), RW (Read/write), E (Enable) is connected to other GPIO Pins of the controller.

Therefore, due to such connections, we can save four GPIO pins which can be used for another application.

Initialization

1. Wait for 15ms, Power-on initialization time for LCD16x2
2. Send 0x02 command which initializes LCD 16x2 in 4-bit mode
3. Send 0x28 command which configures LCD in 2-line, 4-bit mode, and 5x8 dots
4. Send any Display ON command (0x0E, 0x0C)
5. Send 0x06 command (increment cursor)

Command write function

1. First, send a Higher nibble of command
2. Make RS pin low, RS=0 (command reg)
3. Make RW pin low, RW=0 (write operation) or connect it to ground
4. Give High to Low pulse at Enable (E)
5. Send lower nibble of command
6. Give High to Low pulse at Enable (E)

Data write function

1. First, send a Higher nibble of data
2. Make RS pin high, RS=1 (data reg)
3. Make RW pin low, RW=0 (write operation) or connect it to ground
4. Give High to Low pulse at Enable (E)
5. Send lower nibble of data
6. Give High to Low pulse at Enable (E)

BASIC COMMANDS USED IN LCD DISPLAY

COMMANDS	DESCRIPTION
0x01	Clear screen
0x02	return home
0x04	Cursor decrement
0x05	Display shifts to right
0x06	Cursor increment
0x07	Display shifts to left
0x08	Cursor and display OFF
0x10	Cursor position Shifts to left
0x14	Cursor position shifts to right
0x38	Using two lines, 8-bit mode
0x28	Using two lines, 4-bit mode
0x80	Move cursor to the beginning of first line
0x0C	Display ON, cursor OFF
0XC0	Move cursor to the beginning of second line
0x0A	Display OFF, cursor ON
0x0E	Display ON, cursor blinking
0x30	For display in one line in 8-bit mode
0x20	For display in one line in 4-bit mode
0x0F	Display data on cursor blinking
0x18	Shift complete data to left side
0x1C	Shift complete data to right side

L293D DC Motor Driver

PIN Diagram

Power Consumption

L293D Total number of pins = 16 Ic Operating voltage = 5 – 7 v Input voltage = 4.5 – 36 v Output voltage = 4.5 – 36 v Continuous Output Current = 600 mA or 0.6 A

L293 Total number of pins = 28 ​Ic Operating voltage = 5 – 7 v Input voltage = 4.5 – 36 v Output voltage = 4.5 – 36 v ​Continuous Output Current = 1 A

Pin Output Logic

1,2EN: To activate the channel 1 we supply +5v to this pin.
3,4EN: To activate the channel 2 we supply +5v to this pin.
Vcc1: Input voltage to derive the internal circuit (darligton array) = 4.5 to 5 v
Vcc2: Supply/Output to appear at output = 4.5 to 36 v
1A: Channel-1 Input Pin
2A: Channel-1 Input Pin
1Y: Channel-1 Output Pin
2Y: Channel-1 Output Pin
3A: Channel-2 Input Pin
4A: Channel-2 Input Pin
3Y: Channel-2 Output Pin
4Y: Channel-2 Output Pin

1A and 2A are control pins of channel 1. 1Y and 2Y are output pins of channel 1. Similarly 3A and 4A are input pins for channel 2 and 3Y, 4Y are output pins for channel 2. 1,2En are enable pins of channel 1. 3,4 EN are enable pins of channel 2. Individual l293d motor driver channel equivalent circuit is given below.

Program for DC Motor Control and Status Display by Arduino IDE

#include<LiquidCrystal.h> //LCD Heder file inclued

LiquidCrystal lcd(12, 11, 5, 4, 3, 2); //Arduino pin configure for LCD

#define potentiometer A0 //Potentionmeter control given to A0 pin

#define button_CW A1 // Clockwise putton start pin A1

#define button_CCW A2 // Counter clockwise putton pin A2

#define button_STOP A3 // Motor stop Button pin A3

#define M1_12EN 10 //pin 12EN of L293 connected to pin 10

#define M1_1A 9 //pin 1A of L293 connected to pin 9

#define M1_2A 8 //pin 2A of L293 connected to pin 8

int read_ADC=0; //ADC value Declared as integer value

int duty_cycle; //Duty cyce value defined as integer

int duty_cycle_lcd; //Duty cycle of LCD defined as integer

int set = 0; //set value defined as integer

void setup()

{

Serial.begin(9600); //serial communication baud rate 9600

pinMode(potentiometer, INPUT); //Potentiometer input

pinMode(button_CW, INPUT_PULLUP); //Clockwise button input

pinMode(button_CCW, INPUT_PULLUP); //Anti clockwise button input

pinMode(button_STOP, INPUT_PULLUP); //Stop button input

pinMode(M1_12EN, OUTPUT); //L293 12EN input

pinMode(M1_1A, OUTPUT); //L293 1A input

pinMode(M1_2A, OUTPUT); //L293 2A input

lcd.begin(16,2); //16x2 LCD eneble

lcd.setCursor(0,1); //Set cursor on (0,1) place

lcd.print("Hello"); //Initialize LCD

delay(500); //Delay 500ms

lcd.clear(); //clear LCD

}

voidloop()

{

read_ADC = analogRead(potentiometer); //Read potentiometer value analog

duty_cycle = map(read_ADC, 0, 1023, 0,255); //Duty cycle display

duty_cycle_lcd = map(read_ADC, 0, 1023,0, 100);//Duty cycle display

analogWrite(M1_12EN, duty_cycle); //Writ the duty cycle

lcd.setCursor(0,0); //Set LCD cursor 0,0

lcd.print("Duty Cycle:"); //Print "Duty cycle"

lcd.print(duty_cycle_lcd); //Print duty cycl value

lcd.print("% "); //Print %

if(digitalRead (button_CW) == 0)(set = 1); //Read Button value for CW

if(digitalRead (button_CCW) == 0)(set = 2); //Read Button value for CCW

if(digitalRead (button_STOP) == 0)(set = 0); //Read Button value for STOP

lcd.setCursor(0,1); //Set LCD cursor 0,1

if(set==0) // if set value 0 motor is stop

{

lcd.print("Motor Stopped "); //Print the LCD as "Motor stopped"

digitalWrite(M1_1A, LOW); //Assining pin 1A Low for stop the motor

digitalWrite(M1_2A, LOW); //Assining pin 2A Low for stop the motor

}

if(set==1) // if set value 1 motor run CW direction

{

lcd.print("Clockwise "); //Print the LCD as "Motor stopped"

digitalWrite(M1_1A, HIGH); //Assining pin 1A High for run CW

digitalWrite(M1_2A, HIGH); //Assining pin 2A High for run CW

}

if(set==2) // if set value 2 motor run CCW direction

{

lcd.print("Cunter Clockwise "); //Print the LCD as "Counter clockwise"

digitalWrite(M1_1A, LOW); //Assining pin 1A Low for run CCW

digitalWrite(M1_2A, HIGH); //Assining pin 2A High for run CCW

}

delay(50);

}