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  1. #1
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    Feb 2016
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    ESP-01 is remembering old program......

    I have flashed a new esp-01 client program using arduino software. The program is working fine but before this program, i was flashed accesspoint program in my esp. The name of ssid created was 'ESPap' and password 'thereisnospoon'.
    If new program(client) is present in ESP, there should not be created the accesspoint of old name. but it is(Means when i scan for available ssids, it is present there and ask for password to connect. When i put password, the connection becomes successful)...... which is conflicting and disconnecting randomly my home wifi network.
    I also tried the station mode command in void setup,(which i thought, will not broadcast the ssid) but no positive result......
    The new code i used is given in examples..........and here it is.....

    char ssid[] = "ESPL";  //  your network SSID (name)
    char pass[] = "FAFBFCFDFE";       // your network password
    unsigned int localPort = 2390;      // local port to listen for UDP packets
    /* Don't hardwire the IP address or we won't get the benefits of the pool.
     *  Lookup the IP address for the host name instead */
    //IPAddress timeServer(129, 6, 15, 28); // time.nist.gov NTP server
    IPAddress timeServerIP; // time.nist.gov NTP server address
    const char* ntpServerName = "time.nist.gov";
    const int NTP_PACKET_SIZE = 48; // NTP time stamp is in the first 48 bytes of the message
    byte packetBuffer[ NTP_PACKET_SIZE]; //buffer to hold incoming and outgoing packets
    // A UDP instance to let us send and receive packets over UDP
    WiFiUDP udp;
    void setup()
      // We start by connecting to a WiFi network
      Serial.print("Connecting to ");
      WiFi.begin(ssid, pass);
      while (WiFi.status() != WL_CONNECTED) {
      Serial.println("WiFi connected");
      Serial.println("IP address: ");
      Serial.println("Starting UDP");
      Serial.print("Local port: ");
    void loop()
      //get a random server from the pool
      WiFi.hostByName(ntpServerName, timeServerIP); 
      sendNTPpacket(timeServerIP); // send an NTP packet to a time server
      // wait to see if a reply is available
      int cb = udp.parsePacket();
      if (!cb) {
        Serial.println("no packet yet");
      else {
        Serial.print("packet received, length=");
        // We've received a packet, read the data from it
        udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer
        //the timestamp starts at byte 40 of the received packet and is four bytes,
        // or two words, long. First, esxtract the two words:
        unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
        unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
        // combine the four bytes (two words) into a long integer
        // this is NTP time (seconds since Jan 1 1900):
        unsigned long secsSince1900 = highWord << 16 | lowWord;
        Serial.print("Seconds since Jan 1 1900 = " );
        // now convert NTP time into everyday time:
        Serial.print("Unix time = ");
        // Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
        const unsigned long seventyYears = 2208988800UL;
        // subtract seventy years:
        unsigned long epoch = secsSince1900 - seventyYears;
        // print Unix time:
        // print the hour, minute and second:
        Serial.print("The UTC time is ");       // UTC is the time at Greenwich Meridian (GMT)
        Serial.print((epoch  % 86400L) / 3600); // print the hour (86400 equals secs per day)
        if ( ((epoch % 3600) / 60) < 10 ) {
          // In the first 10 minutes of each hour, we'll want a leading '0'
        Serial.print((epoch  % 3600) / 60); // print the minute (3600 equals secs per minute)
        if ( (epoch % 60) < 10 ) {
          // In the first 10 seconds of each minute, we'll want a leading '0'
        Serial.println(epoch % 60); // print the second
      // wait ten seconds before asking for the time again
    // send an NTP request to the time server at the given address
    unsigned long sendNTPpacket(IPAddress& address)
      Serial.println("sending NTP packet...");
      // set all bytes in the buffer to 0
      memset(packetBuffer, 0, NTP_PACKET_SIZE);
      // Initialize values needed to form NTP request
      // (see URL above for details on the packets)
      packetBuffer[0] = 0b11100011;   // LI, Version, Mode
      packetBuffer[1] = 0;     // Stratum, or type of clock
      packetBuffer[2] = 6;     // Polling Interval
      packetBuffer[3] = 0xEC;  // Peer Clock Precision
      // 8 bytes of zero for Root Delay & Root Dispersion
      packetBuffer[12]  = 49;
      packetBuffer[13]  = 0x4E;
      packetBuffer[14]  = 49;
      packetBuffer[15]  = 52;
      // all NTP fields have been given values, now
      // you can send a packet requesting a timestamp:
      udp.beginPacket(address, 123); //NTP requests are to port 123
      udp.write(packetBuffer, NTP_PACKET_SIZE);
    Extra info: ESP forgets the previous ssid and broadcast the new one when i flashed AT command firmware instead of program in it.
    Overall thing which i want is that, my esp should not broadcast it's ssid and should act as only client Don't know, where i am doing wrong???
    Last edited by KlausST; 27th February 2017 at 10:35. Reason: added code tags

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