#define M1_A        2       
#define M1_B        4       
#define M1_PWM      3       
#define SENSOR_PIN  A4      
void setup() {
  Serial.begin(9600);       
  pinMode(M1_A, OUTPUT);    
  pinMode(M1_B, OUTPUT);    
  analogWrite(M1_PWM, 100); 
  digitalWrite(M1_A, HIGH); 
  for (int i=0; i < 2000; i++) {    
    Serial.println(analogRead(SENSOR_PIN));   
  }
  digitalWrite(M1_A, LOW);  
}
void loop() {
}