Controlling the Direction of a Brushed Motor with an H-Bridge

            An H-Bridge can control two brushed motors. Figure 8-10 shows the connections for the L293D H-Bridge IC, you can also use the SN754410 which has the same pin layout.In the sketch in this recipe’s Solution, a single motor is controlled using the IN1 and IN2 pins; the EN pin is permanently HIGH because it is connected to +5V.

The following sketch controls both motors together:

/*

* Brushed_H_Bridge_simple2 sketch

* commands from serial port control motor direction

* + or - set the direction, any other key stops the motors

*/

const int in1Pin = 5; // H-Bridge input pins

const int in2Pin = 4;

const int in3Pin = 3; // H-Bridge pins for second motor

const int in4Pin = 2;

void setup()

{

Serial.begin(9600);

pinMode(in1Pin, OUTPUT);

pinMode(in2Pin, OUTPUT);

pinMode(in3Pin, OUTPUT);

pinMode(in4Pin, OUTPUT);

Serial.println("+ - sets direction of motors, any other key stops motors");

}

void loop()

{

if ( Serial.available()) {

char ch = Serial.read();

if (ch == '+')

{

Serial.println("CW");

// first motor

digitalWrite(in1Pin,LOW);

digitalWrite(in2Pin,HIGH);

//second motor

digitalWrite(in3Pin,LOW);

digitalWrite(in4Pin,HIGH);

}

else if (ch == '-')

{

Serial.println("CCW");

digitalWrite(in1Pin,HIGH);

digitalWrite(in2Pin,LOW);

digitalWrite(in3Pin,HIGH);

digitalWrite(in4Pin,LOW);

}

else

{

Serial.print("Stop motors");

digitalWrite(in1Pin,LOW);

digitalWrite(in2Pin,LOW);

digitalWrite(in3Pin,LOW);

digitalWrite(in4Pin,LOW);

}

}

}