Compare a string from serial input

Projects Programming
1

A string that is coming from the serial port has te match a certain value.
But it never appears to be .
here you see my test script. Why does it not work whan i hive "hello" in the serial?


void setup() {
  Serial.begin(115200);
}

void loop() {
   if (Serial.available() > 0) {
   String c = Serial.readString();
 
   if (c == 'hallo') {
    
     Serial.print("Good!");

} else {Serial.print("Bad!");
}}}
2

Welcome to the forum

Why did you start a topic in the Uncategorised category of the forum ?

Your topic has been moved to a relevant category. Please be careful in future when deciding where to start new topics

3

Single quotes for single characters ('t'). Doube quotes for Strings ("hallo").

Also be aware of line endings appended by serial monitor.

4

try String c = Serial.readStringUntil(0x0A);

void setup() {
  Serial.begin(115200);
  Serial.println("Start");
}

void loop() {
  if (Serial.available() > 0) {
    String c = Serial.readStringUntil(0x0A);
    Serial.println(c);

    if (c == "hallo") {
     
      Serial.print("Good!");

    } else {
      Serial.print("Bad!");
    }
  }
}
5

Try it like this..

6

Thank you for your help, for the simulation below this helps.
For the actual application i try to make, not yet. My arduino is connected to a pc running this software
it send the serial code “9999\r” by plain ASCII. As a response tha arduino has to send a sting to identify itself. Once I could have it sent "9999" back (lost that code). since than i only get a timeout.

It is meant as a challenge but i haven't made it one step so far as i fail this simple communication protocol :frowning:

7

\r is return character in hex 0x0D..
\n is newline character in hex 0x0A..
did you try reading until 0x0D instead of 0x0A??

good luck.. ~q

8

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.