Arduino receive data from software serial

Question

Sorry for my weak English. I'm trying to receive the json data from Sim800 on my Arduino. To read the data on the serial port I used the following code:

while(serialSIM800.available()==0); //Wait until the data is received
    String content = "";
  while(serialSIM800.available()>0){ // When data is received
    content = content + char(char (serialSIM800.read()));
    }
Serial.print(content);

But incomplete data is received. As follows:

{"id":"1212","temp":"24","hum","4

For the better result I used the following code:

 byte x;
char data[128];
void sim800Reply() {
  x=0;
  do{   
    while(serialSIM800.available()==0);
    data[x]=serialSIM800.read();
    Serial.print(data[x]);
    x++;
  } while(!(data[x-1]=='K'&&data[x-2]=='O'));
}

Data is completely received. As follows:

{"id":"1212","temp":"24","hum","45","date":"11.2018","status":"200"}

OK

But I think this code is not good and there are problems.for example If the serialSIM800 is not available like when sim800 are not connected, The following code causes crash while(serialSIM800.available()==0); Because this is always true OR If there is an error and OK Was not received, The following code causes crash while(!(data[x-1]=='K'&&data[x-2]=='O')); Because this is always true.The maximum data length is 120 bytes, What should I do to Receive the Json data from Arduino serial? Thank you all.

score 0 · Answer 1 · answered Nov 08 '18 at 19:24

0

for start try:

if (serialSIM800.available()) {
  String content = serialSIM800.readString();
  Serial.print(content);
}

in setup() add serialSIM800.setTimeut(50);

answered Nov 08 '18 at 19:24

Juraj

3,490
4
18
25

tnx I just used the `serialSIM800.readString()` instead of the `serialSIM800.read()` – omid ebrahimi Nov 08 '18 at 19:58
I doubt it really helped. What with `while(serialSIM800.available()==0);` blocking the loop()? – Juraj Nov 08 '18 at 20:02
I use this code: `while(serialSIM800.available()==0){ delay(2000); return;}` If the serial is not available for two seconds, it will be return. – omid ebrahimi Nov 09 '18 at 12:48
`if (serialSIM800.available()) {` ensures the sketch loops unblocked until data is not available. no need to block the loop – Juraj Nov 09 '18 at 13:13

score 0 · Answer 2 · answered Nov 09 '18 at 17:47

Finally, I changed the code as follows:

 String dump(bool printData) {
      byte while_cunt = 0;
      while (serialSIM800.available() == 0){
        while_cunt++;
        delay(15); // It can change for a proper delay
        if(while_cunt >=250){  // If the data from serial was not received past 3.75 seconds
          Serial.println("return");
          return "";   // Exit from dump function
        }
      }
      String content = "";
      while (serialSIM800.available() > 0) {
        content += serialSIM800.readString();
      }

      if (printData) {
        Serial.println(content);
      }
      return content;
    }

It can return and print serial data And it works fast Because every 15 milliseconds checks that the data has been received and if it has not been received for a certain period of time(In this case 3.75 seconds), it will be out of process and will not crash. Examples for this function:

     serialSIM800.println("AT");
     dump(true); 
// print Received response from sim800

    serialSIM800.println("AT");
    String str =  dump(true); 
    // print Received response from sim800 and Saved in variable named 'str'

    serialSIM800.println("AT");
     String str =  dump(false); 
//Save response  in variable named 'str' without print

Arduino receive data from software serial

2 Answers2