gistfile1.txt

const int trigPin = 8;
const int echoPin = 10;
const int channel_a_enable  = 6;
const int channel_a_input_1 = 4;
const int channel_a_input_2 = 7;
const int channel_b_enable  = 5;
const int channel_b_input_3 = 3;
const int channel_b_input_4 = 2;

void setup() {
  // put your setup code here, to run once:
  pinMode( channel_a_enable, OUTPUT );  // Channel A enable
  pinMode( channel_a_input_1, OUTPUT ); // Channel A input 1
  pinMode( channel_a_input_2, OUTPUT ); // Channel A input 2
  
  pinMode( channel_b_enable, OUTPUT );  // Channel B enable
  pinMode( channel_b_input_3, OUTPUT ); // Channel B input 3
  pinMode( channel_b_input_4, OUTPUT ); // Channel B input 4
  
  Serial.begin( 9600 );
  Serial.println("Starting up");
}

void loop() {
      // establish variables for duration of the ping, 
      // and the distance result in inches and centimeters:
  
      Serial.println("Channel A forward");
      analogWrite( channel_a_enable, 255);
      digitalWrite( channel_a_input_1, HIGH);
      digitalWrite( channel_a_input_2, LOW);


  long duration, inches, cm;

  // The sensor is triggered by a HIGH pulse of 10 or more microseconds.
  // Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
  pinMode(trigPin, OUTPUT);
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the signal from the sensor: a HIGH pulse whose
  // duration is the time (in microseconds) from the sending
  // of the ping to the reception of its echo off of an object.
  pinMode(echoPin, INPUT);
  duration = pulseIn(echoPin, HIGH);

  // convert the time into a distance
  cm = microsecondsToCentimeters(duration);
  if (cm > 150)
  {
  Serial.println("Channel A forward");
      analogWrite( channel_a_enable, 255);
      digitalWrite( channel_a_input_1, HIGH);
      digitalWrite( channel_a_input_2, LOW);
      analogWrite( channel_b_enable, 255);
      digitalWrite( channel_b_input_3, HIGH);
      digitalWrite( channel_b_input_4, LOW);
  } else {
      analogWrite( channel_a_enable, 255);
      digitalWrite( channel_a_input_1, HIGH);
      digitalWrite( channel_a_input_2, LOW);
      analogWrite( channel_b_enable, 255);
      digitalWrite( channel_b_input_3, LOW);
      digitalWrite( channel_b_input_4, HIGH);
  }
}

long microsecondsToCentimeters(long microseconds)
{
    return microseconds / 29 / 2;
}