hi everybody! 
i'm creating a project for my school final exam.. 
i would create a minirobot controlled by pc, on the robot there will be an ip camera..
my arduino and my ipcamera are connected to an access point, connecting my pc to the network i could control the robot with arduino and see the frontal video from the webcam. 8) 
my problem is using the ethernet shield: my arduino is the server and my pc a client, in java on the pc i've just created a program who sends strings (byte to byte) to arduino and it receive it..
my first communication works: if the character received is 'a' i turn on a led, if the char is 's' i turn it off
then i tried to create another program with many characters for the movements of my robot: 'w','a','s','d','x', and so on... it seems that digitalWrite(...,HIGH) doesn't works.. 
(all the motor control is already created and it works perfectly!)
i don't know if it's a logic problem.. someone can help me?
these are the programs:
Led On Off Program (it works):
#include <SPI.h>
#include <Ethernet.h>
#include <stdlib.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 0, 177 };
byte gateway[] = { 192, 168, 0, 1 };
byte subnet[] = { 255, 255, 255, 0 };
// telnet defaults to port 23
EthernetServer server = EthernetServer(23);
void setup()
{
pinMode(2, OUTPUT);
Serial.begin(9600);
Ethernet.begin(mac, ip, gateway, subnet);
server.begin();
}
void loop()
{
char temp;
EthernetClient client = server.available();
if (client == true) {
temp=client.read();
Serial.println(temp);
if(temp=='a')
digitalWrite(2, HIGH);
else if(temp=='s')
digitalWrite(2, LOW);
server.write(temp);
}
}
Motor Code (it doesn't work):
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 0, 177 };
byte gateway[] = { 192, 168, 0, 1 };
byte subnet[] = { 255, 255, 255, 0 };
EthernetServer server = EthernetServer(23);
int motor_left[] = {7, 8}; // pin 15, pin 10 (dell'integrato)
int motor_right[] = {5, 6}; // pin 2, pin 7 (dell'integrato)
int velocita = 9; // PWM, pin 1,9 (dell'integrato)
void setup()
{
Ethernet.begin(mac, ip, gateway, subnet);
for(int i = 0; i < 2; i++){
pinMode(motor_left[i], OUTPUT);
pinMode(motor_right[i], OUTPUT);
}
pinMode(velocita, OUTPUT);
pinMode(2, OUTPUT);
Serial.begin(9600);
server.begin();
}
void loop()
{
char temp;
EthernetClient client = server.available();
if (client == true) {
temp=client.read();
Serial.println(temp);
if(temp=='s')
motor_stop();
else if(temp=='w')
drive_forward();
else if(temp=='x')
drive_backward();
else if(temp=='a')
turn_left();
else if(temp=='d')
turn_right();
else if(temp=='m')
analogWrite(velocita, 255);
else if(temp=='n')
analogWrite(velocita, 140);
server.write(temp);
}
}
void motor_stop(){
digitalWrite(motor_left[0], LOW);
digitalWrite(motor_left[1], LOW);
digitalWrite(motor_right[0], LOW);
digitalWrite(motor_right[1], LOW);
}
void drive_forward(){
digitalWrite(motor_left[0], HIGH);
digitalWrite(motor_left[1], LOW);
digitalWrite(motor_right[0], HIGH);
digitalWrite(motor_right[1], LOW);
}
void drive_backward(){
digitalWrite(motor_left[0], LOW);
digitalWrite(motor_left[1], HIGH);
digitalWrite(motor_right[0], LOW);
digitalWrite(motor_right[1], HIGH);
}
void turn_left(){
digitalWrite(motor_left[0], LOW);
digitalWrite(motor_left[1], HIGH);
digitalWrite(motor_right[0], HIGH);
digitalWrite(motor_right[1], LOW);
}
void turn_right(){
digitalWrite(motor_left[0], HIGH);
digitalWrite(motor_left[1], LOW);
digitalWrite(motor_right[0], LOW);
digitalWrite(motor_right[1], HIGH);
}
