GPRS模块用TCP实现MQTT协议（基于SIM900A）

mqtt部分：

int strlen(char *str)  
{  
    int len = 0;  
    while (*str != '') {  
        len++;  
        str++;  
    }  
    return len;  
}  
  
// **********************************  
// *                                *  
// * 根据主机地址和端口号连接服务器 *  
// *                                *  
// **********************************  
  
  
void tcp_connect(char *host,int port)  
{  
   uart_send_str("AT
");  
   uart_send_str("AT+CPIN? 
");  
   seelp(500);  
   uart_send_str("AT+CREG? 
");  
   seelp(500);  
   uart_send_str("AT+CGATT? 
");  
   seelp(500);  
   uart_send_str("AT+CSTT="CMNET" 
");  
   seelp(500);  
   uart_send_str("AT+CIICR 
");  
   seelp(1500);  
   uart_send_str("AT+CIFSR 
");  
   seelp(1000);  
   uart_send_str("AT+CIPSTART="TCP"\,"23.106.139.167"\,"1883" 
"); //连接TCP Server  8081 1883  
}  
  
  
// *************************  
// *                       *  
// *  构建MQTT连接包       *  
// *                       *  
// *************************  
  
int baseIndex;  
int mqtt_connect_message(unsigned char *mqtt_message,char *client_id,char *username,char *password)  
{   
    char i = 0;    
    char client_id_length = strlen(client_id);    
    int username_length = strlen(username);    
    int password_length = strlen(password);    
    int packetLen = 12 + 2 + client_id_length + 2 + username_length + 2 + password_length;    
        
    mqtt_message[0] = 16;                      // MQTT Message Type CONNECT    
    mqtt_message[1] = packetLen%256;    
    baseIndex = 2;    
    if( packetLen >127 ){//    
        mqtt_message[2] = 1;//packetLen/127;    
        baseIndex = 3;    
    }    
        
        
    mqtt_message[baseIndex] = 0;                       // Protocol Name Length MSB    
    mqtt_message[baseIndex+1] = 6;                       // Protocol Name Length LSB    
    mqtt_message[baseIndex+2] = 77;                      // ASCII Code for M    
    mqtt_message[baseIndex+3] = 81;                      // ASCII Code for Q    
    mqtt_message[baseIndex+4] = 73;                      // ASCII Code for I    
    mqtt_message[baseIndex+5] = 115;                     // ASCII Code for s    
    mqtt_message[baseIndex+6] = 100;                     // ASCII Code for d    
    mqtt_message[baseIndex+7] = 112;                     // ASCII Code for p    
    mqtt_message[baseIndex+8] = 3;                      // MQTT Protocol version = 3    
    mqtt_message[baseIndex+9] = 194;                   // conn flags    
    mqtt_message[baseIndex+10] = 0;                      // Keep-alive Time Length MSB    
    mqtt_message[baseIndex+11] = 60;                     // Keep-alive Time Length LSB    
        
    mqtt_message[baseIndex+12] = 0;                      // Client ID length MSB    
    mqtt_message[baseIndex+13] = client_id_length;       // Client ID length LSB    
        
    baseIndex += 14;    
    // Client ID    
    for(i = 0; i < client_id_length; i++){    
        mqtt_message[baseIndex + i] = client_id[i];    
    }    
        
    baseIndex = baseIndex+client_id_length;    
        
    //username    
    mqtt_message[baseIndex] = 0;                      //username length MSB    
    mqtt_message[baseIndex+1] = username_length;       //username length LSB    
    baseIndex = baseIndex+2;    
    for(i = 0; i < username_length ; i++){    
        mqtt_message[baseIndex + i] = username[i];    
    }    
        
    baseIndex = baseIndex + username_length;    
        
    //password    
    mqtt_message[baseIndex] = 0;                      //password length MSB    
    mqtt_message[baseIndex+1] = password_length;       //password length LSB    
    baseIndex = baseIndex + 2;    
    for(i = 0; i < password_length ; i++){    
        mqtt_message[baseIndex + i] = password[i];    
    }    
        
    baseIndex += password_length;    
    
    return baseIndex;    
}  
  
  
int mqtt_publish_message(unsigned char *mqtt_message, char * topic, char * message) {    
        
    //mqtt_message = 0;    
        
    unsigned char i = 0;    
    unsigned char topic_length = strlen(topic);    
    unsigned char message_length = strlen(message);    
        
    mqtt_message[0] = 48;                                  // MQTT Message Type CONNECT    
    mqtt_message[1] = 2 + topic_length + message_length;   // Remaining length    
    mqtt_message[2] = 0;                                   // MQTT Message Type CONNECT    
    mqtt_message[3] = topic_length;                        // MQTT Message Type CONNECT    
        
    // Topic    
    for(i = 0; i < topic_length; i++){    
        mqtt_message[4 + i] = topic[i];    
    }    
        
    // Message    
    for(i = 0; i < message_length; i++){    
        mqtt_message[4 + topic_length + i] = message[i];    
    }    
        
    return 4 + topic_length + message_length;    
}    
  
  
int subindex = 0;  
int mqtt_subscribe_message(unsigned char *mqtt_message,unsigned char *topic)    
{    
    unsigned char topic_len = strlen(topic);    
    mqtt_message[0] = 130;    
    mqtt_message[1] = topic_len+5;    
    mqtt_message[2] = 0;    
    mqtt_message[3] = 1;    
    mqtt_message[4] = 0;    
    mqtt_message[5] = topic_len;    
  
    for (subindex=0; subindex<topic_len; subindex++) {    
        mqtt_message[6+subindex] = topic[subindex];    
    }    
    mqtt_message[topic_len+6+1] = 0;    
    return topic_len+7;    
}

　　

mqtt部分：

 

 

[cpp] view plain copy
 
  1. int strlen(char *str)  
  2. {  
  3.     int len = 0;  
  4.     while (*str != '') {  
  5.         len++;  
  6.         str++;  
  7.     }  
  8.     return len;  
  9. }  
  10.   
  11. // **********************************  
  12. // *                                *  
  13. // * 根据主机地址和端口号连接服务器 *  
  14. // *                                *  
  15. // **********************************  
  16.   
  17.   
  18. void tcp_connect(char *host,int port)  
  19. {  
  20.    uart_send_str("AT ");  
  21.    uart_send_str("AT+CPIN?  ");  
  22.    seelp(500);  
  23.    uart_send_str("AT+CREG?  ");  
  24.    seelp(500);  
  25.    uart_send_str("AT+CGATT?  ");  
  26.    seelp(500);  
  27.    uart_send_str("AT+CSTT="CMNET"  ");  
  28.    seelp(500);  
  29.    uart_send_str("AT+CIICR  ");  
  30.    seelp(1500);  
  31.    uart_send_str("AT+CIFSR  ");  
  32.    seelp(1000);  
  33.    uart_send_str("AT+CIPSTART="TCP"\,"23.106.139.167"\,"1883"  "); //连接TCP Server  8081 1883  
  34. }  
  35.   
  36.   
  37. // *************************  
  38. // *                       *  
  39. // *  构建MQTT连接包       *  
  40. // *                       *  
  41. // *************************  
  42.   
  43. int baseIndex;  
  44. int mqtt_connect_message(unsigned char *mqtt_message,char *client_id,char *username,char *password)  
  45. {   
  46.     char i = 0;    
  47.     char client_id_length = strlen(client_id);    
  48.     int username_length = strlen(username);    
  49.     int password_length = strlen(password);    
  50.     int packetLen = 12 + 2 + client_id_length + 2 + username_length + 2 + password_length;    
  51.         
  52.     mqtt_message[0] = 16;                      // MQTT Message Type CONNECT    
  53.     mqtt_message[1] = packetLen%256;    
  54.     baseIndex = 2;    
  55.     if( packetLen >127 ){//    
  56.         mqtt_message[2] = 1;//packetLen/127;    
  57.         baseIndex = 3;    
  58.     }    
  59.         
  60.         
  61.     mqtt_message[baseIndex] = 0;                       // Protocol Name Length MSB    
  62.     mqtt_message[baseIndex+1] = 6;                       // Protocol Name Length LSB    
  63.     mqtt_message[baseIndex+2] = 77;                      // ASCII Code for M    
  64.     mqtt_message[baseIndex+3] = 81;                      // ASCII Code for Q    
  65.     mqtt_message[baseIndex+4] = 73;                      // ASCII Code for I    
  66.     mqtt_message[baseIndex+5] = 115;                     // ASCII Code for s    
  67.     mqtt_message[baseIndex+6] = 100;                     // ASCII Code for d    
  68.     mqtt_message[baseIndex+7] = 112;                     // ASCII Code for p    
  69.     mqtt_message[baseIndex+8] = 3;                      // MQTT Protocol version = 3    
  70.     mqtt_message[baseIndex+9] = 194;                   // conn flags    
  71.     mqtt_message[baseIndex+10] = 0;                      // Keep-alive Time Length MSB    
  72.     mqtt_message[baseIndex+11] = 60;                     // Keep-alive Time Length LSB    
  73.         
  74.     mqtt_message[baseIndex+12] = 0;                      // Client ID length MSB    
  75.     mqtt_message[baseIndex+13] = client_id_length;       // Client ID length LSB    
  76.         
  77.     baseIndex += 14;    
  78.     // Client ID    
  79.     for(i = 0; i < client_id_length; i++){    
  80.         mqtt_message[baseIndex + i] = client_id[i];    
  81.     }    
  82.         
  83.     baseIndex = baseIndex+client_id_length;    
  84.         
  85.     //username    
  86.     mqtt_message[baseIndex] = 0;                      //username length MSB    
  87.     mqtt_message[baseIndex+1] = username_length;       //username length LSB    
  88.     baseIndex = baseIndex+2;    
  89.     for(i = 0; i < username_length ; i++){    
  90.         mqtt_message[baseIndex + i] = username[i];    
  91.     }    
  92.         
  93.     baseIndex = baseIndex + username_length;    
  94.         
  95.     //password    
  96.     mqtt_message[baseIndex] = 0;                      //password length MSB    
  97.     mqtt_message[baseIndex+1] = password_length;       //password length LSB    
  98.     baseIndex = baseIndex + 2;    
  99.     for(i = 0; i < password_length ; i++){    
  100.         mqtt_message[baseIndex + i] = password[i];    
  101.     }    
  102.         
  103.     baseIndex += password_length;    
  104.     
  105.     return baseIndex;    
  106. }  
  107.   
  108.   
  109. int mqtt_publish_message(unsigned char *mqtt_message, char * topic, char * message) {    
  110.         
  111.     //mqtt_message = 0;    
  112.         
  113.     unsigned char i = 0;    
  114.     unsigned char topic_length = strlen(topic);    
  115.     unsigned char message_length = strlen(message);    
  116.         
  117.     mqtt_message[0] = 48;                                  // MQTT Message Type CONNECT    
  118.     mqtt_message[1] = 2 + topic_length + message_length;   // Remaining length    
  119.     mqtt_message[2] = 0;                                   // MQTT Message Type CONNECT    
  120.     mqtt_message[3] = topic_length;                        // MQTT Message Type CONNECT    
  121.         
  122.     // Topic    
  123.     for(i = 0; i < topic_length; i++){    
  124.         mqtt_message[4 + i] = topic[i];    
  125.     }    
  126.         
  127.     // Message    
  128.     for(i = 0; i < message_length; i++){    
  129.         mqtt_message[4 + topic_length + i] = message[i];    
  130.     }    
  131.         
  132.     return 4 + topic_length + message_length;    
  133. }    
  134.   
  135.   
  136. int subindex = 0;  
  137. int mqtt_subscribe_message(unsigned char *mqtt_message,unsigned char *topic)    
  138. {    
  139.     unsigned char topic_len = strlen(topic);    
  140.     mqtt_message[0] = 130;    
  141.     mqtt_message[1] = topic_len+5;    
  142.     mqtt_message[2] = 0;    
  143.     mqtt_message[3] = 1;    
  144.     mqtt_message[4] = 0;    
  145.     mqtt_message[5] = topic_len;    
  146.   
  147.     for (subindex=0; subindex<topic_len; subindex++) {    
  148.         mqtt_message[6+subindex] = topic[subindex];    
  149.     }    
  150.     mqtt_message[topic_len+6+1] = 0;    
  151.     return topic_len+7;    
  152. }    

 

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原文地址：https://www.cnblogs.com/jiangzhaowei/p/8777265.html