#define SN754410_12EN 9
#define SN754410_1A 7
#define SN754410_2A 8

void setup() {

        pinMode(SN754410_12EN,OUTPUT);
        pinMode(SN754410_1A,OUTPUT);
        pinMode(SN754410_2A,OUTPUT);
}

void loop () {

        analogWrite ( SN754410_12EN, 127 );
        digitalWrite( SN754410_1A  , HIGH);
        digitalWrite( SN754410_2A  , LOW);
        delay(1000);
        analogWrite ( SN754410_12EN, 255 );
        digitalWrite( SN754410_1A  , LOW);
        digitalWrite( SN754410_2A  , HIGH);
        delay(1000);
        digitalWrite ( SN754410_12EN, HIGH );
        digitalWrite( SN754410_1A  , LOW);
        digitalWrite( SN754410_2A  , HIGH);
        delay(1000);
        digitalWrite ( SN754410_12EN, LOW );
        digitalWrite( SN754410_1A  , LOW);
        digitalWrite( SN754410_2A  , HIGH);
        delay(1000);

}