/* Program 11-1 DC motor speed control using PWM
 * 
 * The H-bridge driver TB6612FNG consists of four half-bridge circuit.
 * This program uses two half-bridges to control the output of M3-M4
 * terminals. A DC motor should be connected between M3 and M4 terminals
 * of the board. Pin 6 is used to control the pulse-width modulation (PWM) of 
 * the output. The duty cycle of the PWM controls the power applied to the motor.
 * Pins 7 and 8 control the direction of the half-bridges and in turn control the
 * direction of the motor.
 * This program speeds up the motor, slows down the motor, reverse the direction 
 * then repeats.
 */
 
const int PWM34 = 6;
const int HalfBridgeLeft = 7;
const int HalfBridgeRight = 8;
 
void setup() {
    pinMode(HalfBridgeRight, OUTPUT);
    pinMode(HalfBridgeLeft, OUTPUT);
} 
 
void loop() {
    /* change motor direction */
    digitalWrite(HalfBridgeRight, HIGH);
    digitalWrite(HalfBridgeLeft, LOW);
 
    /* ramp up the pulse width */
    for(int pulseWidth = 0 ; pulseWidth <= 255; pulseWidth +=5) {
        analogWrite(PWM34, pulseWidth);   /* set pulse width   */
        delay(100);                       /* pause before reverse */
    } 
    
    /* ramp down the pulse width */
    for(int pulseWidth = 255 ; pulseWidth >= 0; pulseWidth -=5) { 
        analogWrite(PWM34, pulseWidth);   /* set pulse width */
        delay(100);                       /* pause before reverse */
    }
    
    /* change motor direction */
    digitalWrite(HalfBridgeRight, LOW);
    digitalWrite(HalfBridgeLeft, HIGH);
    
    /* ramp up the pulse width */
    for(int pulseWidth = 0 ; pulseWidth <= 255; pulseWidth +=5) {
        analogWrite(PWM34, pulseWidth);   /* set pulse width */
        delay(100);                       /* pause before reverse */
    } 
    
    /* ramp down the pulse width */
    for(int pulseWidth = 255 ; pulseWidth >= 0; pulseWidth -=5) { 
        analogWrite(PWM34, pulseWidth);   /* set pulse width */
        delay(100);                       /* pause before reverse */
    }
}