Control your motors with L293D and Arduino

Written by: admin@makezilla

After long research and trial and error, I have came up to a new walkthrough regarding this nice chip, the L293D.

Each project is one project and each one has its own unique power configurations, so you must be aware of the best battery choice and how to distribute voltage through your robot.

I strongly advice you to read the following articles:

Picking Batteries for your Robot
Once you've decided on batteries, how do you regulate the voltage

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L293D gives you the possibility to control two motors in both directions -datasheet

Step 1: Basic implementation

This is the most basic implementation of the chip.

As you can see, a 5V Voltage Regulator is between the battery and pins 1, 9, 16. 

Pin 8 gets power before the VReg, if your motor needs for example 6V you should put 6V directly in this pin, all the other pins should not get more than 5V.

This will work with no problem at all, but if you want to do the right implementation take a look at the next example:

Step 2: Advanced implementation

This is the correct Implementation (with the capacitors), and note that pin 8 is feeded by unregulated voltage. This means that if your motors need more than 5V, you should power this pin with that amount of voltage, and the rest of the circuit with 5V.
 

Step 3: Arduino code

// Use this code to test your motor with the Arduino board:

// if you need PWM, just use the PWM outputs on the Arduino
// and instead of digitalWrite, you should use the analogWrite command

// --------------------------------------------------------------------------- Motors
int motor_left[] = {2, 3};
int motor_right[] = {7, 8};

// --------------------------------------------------------------------------- Setup
void setup() {
Serial.begin(9600);

// Setup motors
int i;
for(i = 0; i < 2; i++){
pinMode(motor_left[i], OUTPUT);
pinMode(motor_right[i], OUTPUT);
}

}

// --------------------------------------------------------------------------- Loop
void loop() { 

drive_forward();
delay(1000);
motor_stop();
Serial.println("1");

drive_backward();
delay(1000);
motor_stop();
Serial.println("2");

turn_left();
delay(1000);
motor_stop();
Serial.println("3");

turn_right();
delay(1000);
motor_stop();
Serial.println("4"); 

motor_stop();
delay(1000);
motor_stop();
Serial.println("5");
}

// --------------------------------------------------------------------------- Drive

void motor_stop(){
digitalWrite(motor_left[0], LOW); 
digitalWrite(motor_left[1], LOW); 

digitalWrite(motor_right[0], LOW); 
digitalWrite(motor_right[1], LOW);
delay(25);
}

void drive_forward(){
digitalWrite(motor_left[0], HIGH); 
digitalWrite(motor_left[1], LOW); 

digitalWrite(motor_right[0], HIGH); 
digitalWrite(motor_right[1], LOW); 
}

void drive_backward(){
digitalWrite(motor_left[0], LOW); 
digitalWrite(motor_left[1], HIGH); 

digitalWrite(motor_right[0], LOW); 
digitalWrite(motor_right[1], HIGH); 
}

void turn_left(){
digitalWrite(motor_left[0], LOW); 
digitalWrite(motor_left[1], HIGH); 

digitalWrite(motor_right[0], HIGH); 
digitalWrite(motor_right[1], LOW);
}

void turn_right(){
digitalWrite(motor_left[0], HIGH); 
digitalWrite(motor_left[1], LOW); 

digitalWrite(motor_right[0], LOW); 
digitalWrite(motor_right[1], HIGH); 
}

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