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I am trying to figure out how to capture the OK or the ERROR from a SIM800l.

I have tried

mySerial.println("AT");
while (mySerial.available() > 0 ) {
String str = mySerial.readString();
Serial.println(str);
     if (str.equals("OK")) {
        Serial.println("ok");
     } else {
        Serial.println("unknown");
     }
   }

But I always getting nothing back?

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  • 1
    Does this answer your question? Comparing a String after reading it from Serial fails. The issue is that the string read from the serial port also contains a closing "newline" character so the comparison fails. You need to strip off the newline. Commented Jul 26, 2021 at 9:41

1 Answer 1

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0

You can use .indexOf to find characters in a String. It returns a -1 if a match is not found. See https://www.arduino.cc/reference/en/language/variables/data-types/string/functions/indexof/

mySerial.println("AT");
String str;

while (mySerial.available() > 0 ) 
{
    str = mySerial.readString();
    Serial.println(str);

    if (str.indexOf("OK") != -1) 
    {
        Serial.println("ok");
    } else if (str.indexOf("ERROR") != -1) 
    {
        Serial.println("error!");
    } else {
        Serial.println("unknown");
    }
}
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