convert String to Char not work correctly about minicore HOT 3 CLOSED

///////////////////////////////////////////////////////////////////////////////////////////////////////
void loop () { 
  ethPaket = ether.packetLoop(ether.packetReceive());
  if(ethPaket) prijemPaketu();
  wdt_reset();         
  if (millis() > timer + 5000) 
  {
    timer = millis();
    power=random(1, 5000);
    t=random(-50, 50);

    dataString = ArduinoID + "&t1=" + t + "&power=" + power + "\r\n";
    dataString.toCharArray(dataChar, 50); 
    
    odeslaniPaketu(dataChar);
  } 
}//end loop

//////////////////////////////////////////////////
void odeslaniPaketu(char dataChar[]){
  ether.browseUrl(PSTR("/shome/arduino/elektromer.php?"), dataChar, server, callback);
}

/* 
 *  Test program
 *  seding data to server 192,168,0,104
*/
#include <EtherCard.h>
#include <avr/wdt.h>
/********************************************************************/
#define DEBUG (true)

String ArduinoID= "ID=03";
static byte mymac[] = { 0x74,0x69,0x69,0x2D,0x33,0x43 };
static byte myip[] = { 192,168,0,36 };
static byte gwip[] = { 192,168,0,1 };
static byte server[] = { 192,168,0,104 };

byte Ethernet::buffer[400]; // tcp ip send and receive buffer
int t,power;

unsigned long timer = millis(); 
uint16_t ethPaket;
String dataString;
const char pageOk[] PROGMEM ="HTTP/1.0 200 OK\r\n Content-Type: text/html\r\n\r\nOK";
/////////////////////////////////////////////////////////////////// called when the client request is complete
static void callback (byte status, word off, word len) {
  Ethernet::buffer[off+300] = 0;
  if DEBUG Serial.println((const char*) Ethernet::buffer + off);   
}
////////////////////////////////////////////////////////////////////////////////////////
void setup () {
  if DEBUG Serial.begin(115200);
  if DEBUG Serial.println(F("Start - DEBUG ON"));
  wdt_enable(WDTO_4S);
  init_ethernet();
}
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////////////////
void loop () { 

  ethPaket = ether.packetLoop(ether.packetReceive());
  if(ethPaket) prijemPaketu();//dotaz na http
  wdt_reset();         
  if (millis() > timer + 5000) 
  {
    timer = millis();
    power=random(1, 5000);
    t=random(-50, 50);

    dataString = ArduinoID + "&t1=" + t + "&power=" + power + "\r\n";
    odeslaniPaketu(dataString);
  } 
}//end loop
/////////////////////////////////////////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////
void odeslaniPaketu(String dataString){

  char dataChar[dataString.length()+1];
  dataString.toCharArray(dataChar, dataString.length()); 
  if DEBUG Serial.println(dataChar);    
  if DEBUG Serial.print(F("<<< REQ "));

  ether.browseUrl(PSTR("/shome/arduino/elektromer.php?"), dataChar, server, callback);
}

/////////////////////////////////////////////////////////////////////////////////////////////////////////
void prijemPaketu(){
  if DEBUG Serial.println(F("<<<------------->>>"));      
  char* data = (char *) Ethernet::buffer + ethPaket;

  if DEBUG Serial.println(data);

  memcpy_P(ether.tcpOffset(), pageOk, sizeof pageOk);
  ether.httpServerReply(sizeof pageOk - 1);
}
////////////////////////////////////////////////////////////////////////////////////////////////
void init_ethernet(void){  
  if (ether.begin(sizeof Ethernet::buffer, mymac,10)== 0) 
    if DEBUG Serial.println(F("Failed Ethernet controller"));

  if (!ether.dhcpSetup()){
    ether.staticSetup(myip, gwip);
    if DEBUG Serial.println(F("No DHCP, Static IP!"));
  }
  
  ether.copyIp(ether.hisip, server);
      
  if DEBUG{ 
      ether.printIp("IP: ", ether.myip);
      ether.printIp("GW: ", ether.gwip);
      ether.printIp("DNS: ", ether.dnsip);
      ether.printIp("DHCP: ", ether.dhcpip); // output IP address of the DHCP server
      ether.printIp("SRV: ", ether.hisip);
  } 
}
////////////////////////////////////////////////////////////////////////////////////////////////