Question

对不起，我的英语不好。我正在尝试从Arduino上的Sim800接收json数据。要读取串行端口上的数据，我使用了以下代码：

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);

但是接收到不完整的数据。如下：

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

为了获得更好的结果，我使用了以下代码：

 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'));
}

数据已完全接收。如下：

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

OK

但是 我认为 该代码不好并且有问题。例如，如果serialSIM800不可用，例如未连接sim800，则以下代码会导致崩溃while(serialSIM800.available()==0);因为始终为真，或者如果发生错误并且未收到OK，则以下代码将导致崩溃while(!(data[x-1]=='K'&&data[x-2]=='O'));因为始终为真。最大数据长度为120个字节，我应该怎么做才能从Arduino串口接收Json数据？谢谢大家。

Answer 1

开始尝试：

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

在setup（）中添加serialSIM800.setTimeut(50);

Answer 2

最后，我将代码更改如下：

 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;
    }

它可以返回并打印串行数据，并且运行速度很快，因为每15毫秒检查一次是否已接收到该数据，如果在一定时间段内（在这种情况下为3.75秒）未接收到该数据，则该数据将消失的过程，不会崩溃。此功能的示例：

     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从软件串行接收数据

2 个答案: