在 HTTPREAD 之后将值存储在变量中 [英] Store value in variable after HTTPREAD

问题描述

我正在使用 GSM SIM900 和 Arduino Uno.我正在为 SIM900 使用 AT 命令.我成功地从 GET 请求中获取数据并显示在串行监视器上，但是在 AT+HTTPREAD 命令之后，我想将数据存储到一个变量中.我怎样才能做到这一点?我从 Web 服务器获取 JSON 对象，我想从该对象获取 Status 属性并将其保存到变量中.

I am working with a GSM SIM900 and an Arduino Uno. I am using AT commands for the SIM900. I am successfully getting data from GET requests and showing on the serial monitor, but after the AT+HTTPREAD command I want to store data into a variable. How can I do this? I am getting a JSON Object from the web server and I want to get the Status property from that object and save it into a variable.

#include <SoftwareSerial.h>
SoftwareSerial gprsSerial(2,3);

void setup() {
  gprsSerial.begin(9600);
  Serial.begin(9600);
  Serial.println("Con");
  delay(2000);
  Serial.println("Done!...");
  gprsSerial.flush();
  Serial.flush();
  // See if the SIM900 is ready
  gprsSerial.println("AT");
  delay(1000);
  toSerial();
  // SIM card inserted and unlocked?
  gprsSerial.println("AT+CPIN?");
  delay(1000);
  toSerial();
  // Is the SIM card registered?
  gprsSerial.println("AT+CREG?");
  delay(1000);
  toSerial();
  // Is GPRS attached?
  gprsSerial.println("AT+CGATT?");
  delay(1000);
  toSerial();
  // Check signal strength
  gprsSerial.println("AT+CSQ ");
  delay(1000);
  toSerial();
  // Set connection type to GPRS
  gprsSerial.println("AT+SAPBR=3,1,\"Contype\",\"GPRS\"");
  delay(2000);
  toSerial();
  // Set the APN
  gprsSerial.println("AT+SAPBR=3,1,\"APN\",\"wap.mobilinkworld.com\"");
  delay(2000);
  toSerial();
  // Enable GPRS
  gprsSerial.println("AT+SAPBR=1,1");
  delay(10000);
  toSerial();
  // Check to see if connection is correct and get your IP address
  gprsSerial.println("AT+SAPBR=2,1");
  delay(2000);
  toSerial();
}

void loop() {
  // initialize http service
  gprsSerial.println("AT+HTTPINIT");
  delay(2000); 
  toSerial();
  // set http param value
  // ToDO : send dynamic value
  gprsSerial.println("AT+HTTPPARA=\"URL\",\"http://smockfyp.azurewebsites.net/api/Device/GetStatus?did=1\"");
  delay(4000);
  toSerial();
  // set http action type 0 = GET, 1 = POST, 2 = HEAD
  gprsSerial.println("AT+HTTPACTION=0");
  delay(6000);
  toSerial();
  // read server response
  gprsSerial.println("AT+HTTPREAD");
  delay(1000);
  toSerial();
  gprsSerial.println("AT+HTTPTERM");
  toSerial();
  delay(300);
  gprsSerial.println("");
  delay(10000);
}

void toSerial() {
  while(gprsSerial.available()!=0) {
    Serial.write(gprsSerial.read());
  }
}

这是我想存储在变量中的输出:

This is piece of output I want to store in a variable:

AT+HTTPINIT

OK
AT+HTTPPARA="URL","http://smockfyp.azurewebsites.net/api/DeviceAT+HTTPACTION=0

OK

+HTTPACTION: 0,200,17
AT+HTTPREAD

+HTTPREAD: 17
[{"Status":true}]
OK

推荐答案

首先你应该初始化一个名为 a 的字符数组来存储值，同时声明一个变量 int flag=0;.

First you should initialize a char array named a for storing the value and also declare a variable int flag=0;.

然后修改你的 toSerial() 函数如下:

Then modify your toSerial() function as follows:

void toSerial() {
  while(gprsSerial.available()!=0) {
    if( gprsSerial.read() == '[' )
      flag=2;
    else if(flag == 2 && gprsSerial.read() == ':')
      while(gprsSerial.read() != '}') {
        a[i]= gprsSerial.read();
        i++;
      }
    else if(flag == 0)
      Serial.write(gprsSerial.read());
    else
      flag--;
  }
}

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