I'm currently using google geolocation to get location data to one nodemcu and sending it through serial to another Arduino. The serial command I'm getting right now is,


I'm using the following code to parse it.

 if (Serial.available())  {
    char c = Serial.read();  //gets one byte from serial buffer
    //if (c == '\n') {  //looks for end of data packet marker
    if (c == '\n') {
     // Serial.println(readString); //prints string to serial port out
      //do stuff      
      substring = readString.substring(0,8);
      lati = substring;
      loc = readString.indexOf("T");
      substring = readString.substring(loc+1, loc+11);
     longi = substring;
       readString=""; //clears variable for new input

    else {     
      readString += c; //makes the string readString

It works most of the time but sometimes I get 'T' inside the string as well. like this


What's wrong in my code?

  • what is the reason for transmitting the H? ... you only need the T to separate the two values
    – jsotola
    Jun 23, 2019 at 6:54
  • Can you show us the actual serial String, that you received in that case?
    – chrisl
    Jun 23, 2019 at 9:17

1 Answer 1


with readBytesUntil and C string

if (Serial.available()) {
  char buff[32];
  int l = Serial.readBytesUntil('\n', buff, sizeof(buff));
  if (l > 0 && buff[l - 1] == '\r') {
    l--; // to remove \r if it is there
  buff[l] = 0; // terminate the string
  char* p = strchr(buff,'T'); // returns pointer in string
  if (p != NULL) {
    *p = 0; // write 0 as char at pointer to terminate the first part
    p++; // move the pointer to next char
  } else {

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