#include <SoftwareSerial.h>

char Word;//宣告變數

const int In1 = 4;          // 宣告整數常數In1，宣告為4號腳位
const int In2 = 5;
const int In3 = 6;      
const int In4 = 7; 

void setup() {

  Serial.begin(9600);  
  pinMode(In1, OUTPUT);       
  pinMode(In2, OUTPUT);                          
  pinMode(In3, OUTPUT);
  pinMode(In4, OUTPUT);                  

  Stop();                  //先讓車停下來
}

void loop() {
if(Serial.available()){
  Word=Serial.read();
  Serial.println(Word);
  
  switch(Word){
    case'F':
    Forward();
    break;
    
    case'B':
    Backward();
    break;
    
    case'R':
    Right();
    break;
    
    case'L':
    Left();
    break;
    
    case'S':
    Stop();
    break;
  }
}
 
}


void Forward(){                     // 宣告函數 forward()
  digitalWrite(In1, HIGH);        
  digitalWrite(In2, LOW);           // 輸出數位訊號的指令(接腳編號, 輸出訊號)
  digitalWrite(In3, HIGH);                          
  digitalWrite(In4, LOW);           // 高電位(HIGH或1)  低電位(LOW或0)
}                                                                

void Backward(){
  digitalWrite(In1, LOW);                       
  digitalWrite(In2, HIGH);
  digitalWrite(In3, LOW);
  digitalWrite(In4, HIGH);
}

void Right(){
  digitalWrite(In1, LOW);                            
  digitalWrite(In2, HIGH);
  digitalWrite(In3, HIGH);
  digitalWrite(In4, LOW);
}

void Left(){
  digitalWrite(In1, HIGH);                           
  digitalWrite(In2, LOW);
  digitalWrite(In3, LOW);
  digitalWrite(In4, HIGH);
}

void Stop(){                                     
  digitalWrite(In1, LOW);                           
  digitalWrite(In2, LOW);
  digitalWrite(In3, LOW);
  digitalWrite(In4, LOW);
 }