如何从嵌入式 C 中的 GSM 调制解调器读取消息? [英] How to read messages from GSM modem in Embedded C?

问题描述

我目前正在物联网"域下开展我的迷你项目.我选择使用 GSM 模块设计一个无线布告板.

I am currently working on my mini-project under the domain "Internet of Things". I chose to design a wireless Notice board using a GSM module.

我将项目分为两个模块.一、完美完成的Arduino-LED板卡接口.

I divided the project into two modules. First, the Arduino-LED board interface which perfectly completed.

二、GSM-Arduino接口.基本上，一条消息/短信将从手机发送到 GSM 模块，然后我们必须使用 Arduino 从 GSM 模块读取该消息.我在这里面临一个问题.消息正在发送到 GSM 调制解调器，但我无法读取它.我尝试编写不同的代码，但它不起作用.消息未显示.

Second, GSM-Arduino interface. Basically, a message/SMS will be sent from the mobile phone to the GSM module and then we have to read that message from GSM module using Arduino. I am facing a problem here. The message is being sent to the GSM modem but I am not able to read it. I tried writing different codes, but its not working. The message is not being displayed.

这是我试过的代码片段.

Here is the code snippet I tried.

`#include SoftwareSerial.h

SoftwareSerial SIM900A(2,3);// RX | TX

// Connect the SIM900A TX to Arduino pin 2 RX 

// Connect the SIM900A RX to Arduino pin 3 TX.


void setup()
{ 

      SIM900A.begin(9600);   // Setting the baud rate of GSM Module 

      Serial.begin(9600);    // Setting the baud rate of Serial Monitor(Arduino)

      Serial.println ("SIM900A Ready");

      delay(100);

      Serial.println (" Press s to send and r to recieve ");

}

 void loop()
 {

     if (Serial.available()>0)

     switch(Serial.read())

     {

       case 's':  SendMessage();
               break;

       case 'r':  RecieveMessage();
               break;

      }

    if (SIM900A.available()>0)

        Serial.write(SIM900A.read());

}


 void SendMessage()
{

     SIM900A.println("AT+CMGF=1");    //Sets the GSM Module in Text Mode

     delay(1000);  // Delay of 1000 milli seconds or 1 second

     Serial.println ("Set SMS Number");

     SIM900A.println("AT+CMGS=\"+91xxxxxxxxxx\"\r"); //Replace with your mobileno.

     delay(1000);

     Serial.println ("Set SMS Content");

    SIM900A.println("Hello, I am SIM900A GSM Module");// The SMS text you want to send

     delay(100);

     Serial.println ("Finish");

     SIM900A.println((char)26);// ASCII code of CTRL+Z

     delay(1000);

     Serial.println (" ->SMS Sent");
}


 void RecieveMessage()
{

     Serial.println ("SIM900A Receiving SMS");

     delay (1000);

     SIM900A.println("AT+CNMI=2,2,0,0,0"); // AT Command to receive a live SMS

     delay(1000);

     Serial.write (" ->Unread SMS Recieved");

 }`

推荐答案

您可能需要使用以下命令将首选短信存储设置为 SIM 卡:

You might have to set the preferred SMS storage to SIM card using the command:

SIM900A.print("AT+CPMS=\"SM\"\r");

此外，将此命令移至 setup():

Also, move this command to setup():

SIM900A.print("AT+CMGF=1\r");

最后，请注意我是如何使用 SIM900A.print() 而不是 SIM900A.println() 并在每个命令后发送 '\r' 或 0x0d 的.println() 发送\n\r"，这会导致某些调制解调器出现问题.

Lastly, note how I have used SIM900A.print() instead of SIM900A.println() and send a '\r' or 0x0d after each command. println() sends a "\n\r" and that causes problems in some modems.

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