Esp8266 access to cloud platform ----- DNS domain name connection server

Catalog

Preface

Suppose I want to visit Baidu search server

stay user_init in

In the callback function of software timing

In the network connection initialization function

DNS_ End of domain name resolution _ Callback function

TCP Callback function for successful connection establishment

  Successful connection

Command prompt

---

Preface

Introduce 8266 How to get through the domain name ip Address , So as to connect to the corresponding server on the Internet

【 domain name 】Domain Name, A string of characters separated by dots , It's a certain station on the Internet / Name of a group of computers .

【DNS】 ==Domain Name System【 The domain name system 】 It enables us to directly use domain names to access the corresponding computers or servers on the Internet

Suppose I want to visit Baidu search server

The first one is The method is to use  ip Address to access , Such as 123.125.115.110 Successfully visit Baidu search server

The second kind It is accessed through the domain name of Baidu search www.baidu.com, First, the domain name system will convert this domain name into the corresponding ip Address followed by ip Address to visit Baidu search server

adopt 【 Ruisheng net 】 domain name   Parsing 【 Ruisheng net 】 Of IP Address ,8266 Use the parsed IP Address to 【 Ruisheng net 】

#define 	DN_Server			"www.rationmcu.com"		// 【 Ruisheng net 】 domain name 

stay user_init in

take 8266 Set to sta Mode and software timing

void ICACHE_FLASH_ATTR user_init(void)
{
	uart_init(115200,115200);	//  Initialize the serial port baud rate 
	os_delay_us(10000);			//  Wait for the serial port to stabilize 
	os_printf("\r\n=================================================\r\n");
	os_printf("\t Project:\t%s\r\n", ProjectName);
	os_printf("\t SDK version:\t%s", system_get_sdk_version());
	os_printf("\r\n=================================================\r\n");

	// OLED Display initialization 
	//------------------------------------------------------------
	OLED_Init();							// OLED initialization 
	OLED_ShowString(0,0,"ESP8266-Client");	// ESP8266-Client
	OLED_ShowString(0,2,"IP:");				// ESP8266_IP
	OLED_ShowString(0,4,"rationmcu.com");	// www.rationmcu.com
	OLED_ShowString(0,6,"IP:");				//  The server _IP
	//------------------------------------------------------------

	LED_Init_JX();		// LED initialization 


	ESP8266_STA_Init_JX();			// ESP8266_STA initialization 

	OS_Timer_IP_Init_JX(1000,1);	// 1 Second repetition timing ( obtain IP Address )
}

In the callback function of software timing

Judge if you succeed in obtaining ip Address , Then turn off the timer and initialize the network connection

//  Callback function of software timing 
//=========================================================================================================
void ICACHE_FLASH_ATTR OS_Timer_IP_cb(void)
{
	u8 C_LED_Flash = 0;				// LED Scintillation meter 

	struct ip_info ST_ESP8266_IP;	// ESP8266 Of IP Information 
	u8 ESP8266_IP[4];				// ESP8266 Of IP Address 


	//  Successful access to WIFI【STA In mode , If open DHCP( Default ), be ESO8266 Of IP Address by WIFI Router automatic allocation 】
	//-------------------------------------------------------------------------------------
	if( wifi_station_get_connect_status() == STATION_GOT_IP )	//  Determine whether to obtain IP
	{
		wifi_get_ip_info(STATION_IF,&ST_ESP8266_IP);	//  obtain STA Of IP Information 
		ESP8266_IP[0] = ST_ESP8266_IP.ip.addr;			// IP Eight digits higher than the address  == addr Lower eight 
		ESP8266_IP[1] = ST_ESP8266_IP.ip.addr>>8;		// IP Next highest eight digits of address  == addr Lower eight 
		ESP8266_IP[2] = ST_ESP8266_IP.ip.addr>>16;		// IP Address lower eight digits  == addr Second highest eight 
		ESP8266_IP[3] = ST_ESP8266_IP.ip.addr>>24;		// IP Lower eight digits of address  == addr Top eight digit 

		//  Show ESP8266 Of IP Address 
		//------------------------------------------------------------------------------------------------
		os_printf("\nESP8266_IP = %d.%d.%d.%d\n",ESP8266_IP[0],ESP8266_IP[1],ESP8266_IP[2],ESP8266_IP[3]);
		OLED_ShowIP(24,2,ESP8266_IP);	// OLED Show ESP8266 Of IP Address 
		//------------------------------------------------------------------------------------------------

		//  Access WIFI After success ,LED Flash 3 Time 
		//----------------------------------------------------
		for(; C_LED_Flash<=5; C_LED_Flash++)
		{
			GPIO_OUTPUT_SET(GPIO_ID_PIN(4),(C_LED_Flash%2));
			delay_ms(100);
		}


		os_timer_disarm(&OS_Timer_IP);	//  off timer 

		ESP8266_NetCon_Init_JX();		//  Initialize the network connection (TCP signal communication )
	}
}

In the network connection initialization function

Assign a value to the local port and the remote server port , Here we only know the domain name of the remote server , I don't know about the remote server ip Address , So far end server ip The address cannot be assigned temporarily

Use this API To carry out DNS initialization   , Parameter 2 is represented by macro definition . Parameter 3 ip Address structure pointer, so we need to define a ip Address structure . Parameter 4 is the callback function after domain name resolution

When we finish executing this statement ,8266 Domain name resolution

	//  Get the corresponding IP Address 
	//【 Parameters 1： Network connection structure pointer  /  Parameters 2： Domain name string pointer  /  Parameters 3：IP Address structure pointer  /  Parameters 4： Callback function 】
	//-------------------------------------------------------------------------------------------------
	espconn_gethostbyname(&ST_NetCon, DN_Server, &IP_Server, DNS_Over_Cb_JX);

after Successfully registered connection callback function 、 Exception disconnect callback function , But you can't take 8266 Connect to tcp_server, Because the server is 【 Ruisheng net 】 Of ip We don't know the address yet , When 8266 After the domain name resolution , He will enter Callback function for the end of domain name resolution

void ICACHE_FLASH_ATTR ESP8266_NetCon_Init_JX()
{
	//  Structure assignment 
	//--------------------------------------------------------------------------
	ST_NetCon.type = ESPCONN_TCP ;				//  Set to TCP agreement 

	ST_NetCon.proto.tcp = (esp_tcp *)os_zalloc(sizeof(esp_tcp));	//  Open up memory 


	// ESP8266 As TCP_Client, Want to connect TCP_Server, You must know TCP_Server Of IP Address 
	//--------------------------------------------------------------------------------
	ST_NetCon.proto.tcp->local_port = espconn_port() ;	//  Local port 【 Get available ports 】
	ST_NetCon.proto.tcp->remote_port = 80;				//  Target port 【HTTP Port number 80】
	//u8 remote_ip[4] = {121,198,34,91};				//  The goal is IP【www.rationmcu.com】
	//os_memcpy(ST_NetCon.proto.udp->remote_ip,remote_ip,4);

	//  Get the corresponding IP Address 
	//【 Parameters 1： Network connection structure pointer  /  Parameters 2： Domain name string pointer  /  Parameters 3：IP Address structure pointer  /  Parameters 4： Callback function 】
	//-------------------------------------------------------------------------------------------------
	espconn_gethostbyname(&ST_NetCon, DN_Server, &IP_Server, DNS_Over_Cb_JX);


	//  Successfully registered connection callback function 、 Exception disconnect callback function 
	//--------------------------------------------------------------------------------------------------
	espconn_regist_connectcb(&ST_NetCon, ESP8266_TCP_Connect_Cb_JX);	//  register TCP Callback function for successful connection establishment 
	espconn_regist_reconcb(&ST_NetCon, ESP8266_TCP_Break_Cb_JX);		//  register TCP Callback function with abnormally disconnected connection 


	//  Connect  TCP server
	//----------------------------------------------------------
	//espconn_connect(&ST_NetCon);	//  Connect TCP-server
}

DNS_ End of domain name resolution _ Callback function

If ip The address structure pointer is equal to 0 The domain name resolution fails , If ip The address structure pointer is not equal to 0 And parsed ip The address is not 0 Words , The domain name resolution is successful , The serial port prints the string of successful domain name resolution and obtains the server ( Ruisheng net ) Of ip Address , take ip Copied to the tcp Connect , Serial port printing and oled Show Ruisheng's IP Address , Then call API take 8266 Connect to Ruisheng

// DNS_ End of domain name resolution _ Callback function 【 Parameters 1： Domain name string pointer  /  Parameters 2：IP Address structure pointer  /  Parameters 3： Network connection structure pointer 】
//=========================================================================================================
void ICACHE_FLASH_ATTR DNS_Over_Cb_JX(const char * name, ip_addr_t *ipaddr, void *arg)
{
	struct espconn * T_arg = (struct espconn *)arg;	//  Cache network connection structure pointer 

	//………………………………………………………………………………
	if(ipaddr == NULL)		//  Domain name resolution failed 
	{
		os_printf("\r\n---- DomainName Analyse Failed ----\r\n");

		return;
	}

	//……………………………………………………………………………………………………………
	else if (ipaddr != NULL && ipaddr->addr != 0)		//  Domain name resolution succeeded 
	{
		os_printf("\r\n---- DomainName Analyse Succeed ----\r\n");

		IP_Server.addr = ipaddr->addr;					//  Get server IP Address 


		//  The server that will be resolved to IP The address is set to TCP Remote end of connection IP Address 
		//------------------------------------------------------------------------------
		os_memcpy(T_arg->proto.tcp->remote_ip, &IP_Server.addr, 4);	//  Setup server IP Address 


		//  Show 【 Ruisheng net 】 Of IP Address 
		//------------------------------------------------------------------------------
		os_printf("\r\nIP_Server = %d.%d.%d.%d\r\n",						//  Serial printing 
				*((u8*)&IP_Server.addr),	*((u8*)&IP_Server.addr+1),
				*((u8*)&IP_Server.addr+2),	*((u8*)&IP_Server.addr+3));
		OLED_ShowIP(24,6,T_arg->proto.tcp->remote_ip);						// OLED Show 
		//------------------------------------------------------------------------------

		//  Successfully registered connection callback function 、 Exception disconnect callback function 
		//----------------------------------------------------------------------------------------------
		//espconn_regist_connectcb(T_arg, ESP8266_TCP_Connect_Cb_JX);	//  register TCP Callback function for successful connection establishment 
		//espconn_regist_reconcb(T_arg, ESP8266_TCP_Break_Cb_JX);		//  register TCP Callback function with abnormally disconnected connection 


		//  Connect  TCP server
		//----------------------------------------------------------
		espconn_connect(T_arg);	//  Connect TCP-server
	}
}

TCP Callback function for successful connection establishment

When tcp After the connection is established successfully , Serial printing ESP8266_TCP_Connect_OK The string of successful connection

void ICACHE_FLASH_ATTR ESP8266_TCP_Connect_Cb_JX(void *arg)
{
	espconn_regist_sentcb((struct espconn *)arg, ESP8266_WIFI_Send_Cb_JX);			//  Register the callback function for sending network data successfully 
	espconn_regist_recvcb((struct espconn *)arg, ESP8266_WIFI_Recv_Cb_JX);			//  Register the callback function for successful network data reception 
	espconn_regist_disconcb((struct espconn *)arg,ESP8266_TCP_Disconnect_Cb_JX);	//  Registration successfully disconnected TCP Connected callback function 

	os_printf("\n--------------- ESP8266_TCP_Connect_OK ---------------\n");
}

 

  Successful connection

explain 8266 Successfully resolved to Ruisheng's ip Address 8.129.233.140, And successfully connected to Ruisheng network

Command prompt

We can see here that he passes the command prompt , To get Ruisheng ip Address , With us 8266 Resolved ip The address is the same , explain 8266 The domain name was successfully resolved to ip Address

Maybe someone will ask , Can we parse in advance 8266 The domain name to be connected ？ Then write the resolved address directly to 8266 In the process of , In this case 8266 You don't need domain name resolution

answer ： In theory, it is possible to do so , But this is not recommended

①： A server is a computer , It may break , It may be scrapped , It is possible to move the position ,IP The address may change
②： If the server's IP The address has changed , that , Burned into the chip IP The address is wrong , Need to re burn , It is very troublesome in large quantities
③： The domain name will not be changed easily , Just know the domain name , You can get the server IP Address

Therefore, it is recommended that you use domain names to access servers on the Internet