Electronic Circuits and Projects Forum

1. i following this code for surely direction control motor DC trough serial port communication w/ linksys AP device

Code :

if ((PORTB_val & (left + right)) == (left + right))
  {    
    PORTB_val = PORTB_val - right;    
  }
 
  if ((PORTB_val & (forward + backward)) == (forward + backward))
  {
    PORTB_val = PORTB_val - backward; 
  }

but finally i just have control 2 command : right & backward w/ the same time then left & forward same too
anybody solve this problem

Code :

#define DEBUG 0
#define WAIT_FOR_START 1
 
unsigned char incomingByte = 0;
unsigned long loop_count = 0;
unsigned char horn = 32;
unsigned char redLED = 64;
unsigned char greenLED = 128;
 
unsigned char forward = 1;
unsigned char backward = 2;
unsigned char left = 4;
unsigned char right = 8;
 
unsigned char PORTB_val;
 
 
unsigned char in_char = 0;
 
void setup() 
{
 
//PORTB = digital IO 8 - 13  
//right, left, backwards, forward
 
  pinMode(8, OUTPUT);      // sets the digital pin as output
  pinMode(9, OUTPUT);      // sets the digital pin as output
  pinMode(10, OUTPUT);     // sets the digital pin as output
  pinMode(11, OUTPUT);     // sets the digital pin as output
 
  Serial.begin(9600);      // set up Serial library at 9600 bps
 
 }
 
char get_char()
{
//Function that waits for a character from the serial port
//If none are received, it returns 0.
//The timeout is so that if the router stops sending data to the microcontroller,
//the micrcontroller will stop driving the car, rather than just going forever with
//the last command.  Timeout is around 250mS.
 
  while (loop_count < 30000)
  {
    loop_count++;
 
    if (Serial.available() > 0)
    {
      incomingByte = Serial.read();
      loop_count = 0;
      return incomingByte; 
    }
  }  
 
  loop_count = 0;
 
  #if DEBUG
        Serial.print('X', BYTE);
  #endif
 
  return 0; 
}
 
unsigned char wait_for_start()
{
//Waits for startup message from router serial port
#if WAIT_FOR_START
 
  #if DEBUG
    Serial.println("Waiting...");
  #endif
 
  while(1)
  {
    if (get_char() == 'j' && get_char() == 'b' && get_char() == 'p' && get_char() == 'r' && get_char() == 'o') 
  { 
 
  #if DEBUG
      Serial.print("Passcode Accepted");
  #endif
 
      return 0; 
    }
  }
#endif
}
 
void loop()                       
{  
//Function that processes input from serial port and drives the car based
//on that input.
 
  in_char = get_char();
 
  //Split byte received in to upper and lower halves.
  PORTB_val = in_char & 0x0F;
 
 
  //Make sure the greenLED is turned on now.
 
  //The following IF statements are sanity checks to make sure that FORWARD and BACKWARD cannot be on at the same time
  //and that LEFT and RIGHT can't be on at the same time.
  if ((PORTB_val & (left + right)) == (left + right))
  {    
    PORTB_val = PORTB_val - right;    
  }
 
  if ((PORTB_val & (forward + backward)) == (forward + backward))
  {
    PORTB_val = PORTB_val - backward; 
  }
 
  //Write the processed values to the ports.
 
  PORTB = PORTB_val;
 
  #if DEBUG
    Serial.print(PORTB, HEX);
  #endif
 
}

my project control robot wifi with android device using wirelles linksys
communication data using socket programming

2. data from the client socket in the form of a byte and then through a serial port its happen analog voltage convert to digital voltage trought IC max 232. is it true? little be confused for procces data delivery in the form byte to data that understanding microcontroler to motor DC ?
any idea