void setup() {
    Serial.begin(9600);        // Initialize serial communications with the PC

    // disable SD SPI
    pinMode(4, OUTPUT);
    digitalWrite(4, HIGH);

    // disable w5100 SPI
    pinMode(10, OUTPUT);
    digitalWrite(10, HIGH);

    SPI.begin();                // Init SPI bus
    mfrc522.PCD_Init();        // Init MFRC522 card
    //Serial.println("Scan a MIFARE Classic PICC to demonstrate Value Blocks.");

    Ethernet.begin(mac, ip); //we used a STATIC address to start ETHERNET

    // print your local IP address:
    Serial.print("My IP address: ");
    for (byte thisByte = 0; thisByte < 4; thisByte++) {
        // print the value of each byte of the IP address:
        Serial.print(Ethernet.localIP()[thisByte], DEC);
    // give the Ethernet shield a second to initialize:

void loop() {

    // Prepare key - all keys are set to FFFFFFFFFFFFh at chip delivery from the factory.
    MFRC522::MIFARE_Key key;
            key.keyByte[0] = 0xFF;
            key.keyByte[1] = 0xFF;
            key.keyByte[2] = 0xFF;
            key.keyByte[3] = 0xFF;
            key.keyByte[4] = 0xFF;
            key.keyByte[5] = 0xFF;

    // Look for new cards
    if ( ! mfrc522.PICC_IsNewCardPresent()) {

    // Select one of the cards
    if ( ! mfrc522.PICC_ReadCardSerial()) {
    // Now a card is selected. The UID and SAK is in mfrc522.uid.

    // Dump UID
    //Serial.print("Card UID:");
    //Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : "");

    // In this sample we use the second sector (ie block 4-7). the first sector is = 0
    // scegliere settore di lettura da 0 = primo settore 
    byte sector         = 0;
    // block sector 0-3(sector0) 4-7(sector1) 8-11(sector2)
    // blocchi di scrittura da 0-3(sector0) 4-7(sector1) 8-11(sector2)
    byte valueBlockA    = 0;
    byte valueBlockB    = 1;
    byte valueBlockC    = 2;
    byte trailerBlock   = 3;
    byte status;
    // Authenticate using key A.
    // avvio l'autentificazione A
    //Serial.println("Authenticating using key A...");
    status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, trailerBlock, &key, &(mfrc522.uid));
    if (status != MFRC522::STATUS_OK)
        Serial.print("PCD_Authenticate() failed: ");        

   //No KEY B Authentication              
   int val1 =(mfrc522.uid.uidByte[0]);
   int val2 =(mfrc522.uid.uidByte[1]);
   int val3 =(mfrc522.uid.uidByte[2]);
   int val4 =(mfrc522.uid.uidByte[3]);

   String valA=String(val1);
   String valB=String(val2);
   String valC=String(val3);
   String valD=String(val4);


   // Halt PICC

   // Stop encryption on PCD

   if (counter>first)
   {//delay ifs
       // enable w5100 SPI 
       if (client.connect(server, 80)) { //start of IF
           client.print("GET /accessdenyrfid.php?rfid="); //dont make these println 
           client.print(uID);   //dont make these println

            //client.print( ip );
            //client.print( ipkey );

            client.println(" HTTP/1.1");   //println
            client.println("Host: ");    //println
            client.print(server);//don't make println
            client.println("Connection: close");  //println
            client.println();   //terminates the query
            // add this
            while(client.connected()) {
                while(client.available()) {
                    char ch = client.read();


       } //end OF IF
    }//delay ifs   

The code above works perfectly with another php. that either saves or denies a card into a database. The arduino sends and receives data back and forth from and to php in less than a second. But the problem is that whenever the function client.stop is called. It takes approx. 8 seconds before another data is sent in the loop function. I need the loop to continue with just 2 second interval, which is enough or even faster. I don't think that the mysql query in the php is the one that makes it longer cause all the queries are made before the delay starts. (The server has already sent it's response, before the delay starts, which i think is in the client.stop.) Please help me on other alternatives on stopping the client or any way I can do this faster. Thanks, I'm really in trouble right now. I'm using Arduino UNO. Data sent back and forth are just a couple of letters and numbers.

  • Could you post the full code? There's a bit missing...
    – Avamander
    Commented Feb 10, 2016 at 19:04

1 Answer 1


I would bet the problem relies on

if (counter>first)

As seems like you never reset counter, there might be weird things going on

  • Can you please edit your answer to explain why this causes the code in question and how it should be fixed? Thanks! Commented Apr 16, 2015 at 1:01
  • 1
    @AnnonomusPenguin Edited
    – Lesto
    Commented Apr 16, 2015 at 3:01
  • 1
    I can't even see where counter is declared, nor first.
    – Nick Gammon
    Commented Jul 15, 2015 at 5:51

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