ESP8266 AP_ UDP_ Server

Catalog

 1. Definition espconn Type structure ( Network connection structure )

2. Next, we need to assign values to the network connection structure , Here we set it to udp There are two ways to communicate

Next we need to udp Assignment of communication structure  

 3. register / Define callback function

4. call UDP initialization API 

Callback function for successfully sending network data

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udp signal communication 8266 As a server, wait for the client to actively initiate communication with him

 1. Definition espconn Type structure ( Network connection structure )

struct espconn ST_NetCon;    // notes ： Must be defined as a global variable , The kernel will use this variable ( Memory )

struct espconn {
    /** type of the espconn (TCP, UDP) */
    enum espconn_type type;    // Type of network connection  tcp/udp
    /** current state of the espconn */
    enum espconn_state state;   // Status of network connection 
    union {
        esp_tcp *tcp;
        esp_udp *udp;
    } proto;
    /** A callback function that is informed about events for this espconn */
    espconn_recv_callback recv_callback;   // Callback function 
    espconn_sent_callback sent_callback;   // Callback function 
    uint8 link_cnt;             // Number of connections 
    void *reverse;              //void*  The pointer 
};

typedef struct _esp_udp {
    int remote_port;     // Remote host port number 
    int local_port;     //8266 Port number 
    uint8 local_ip[4];   //8266ip Address 
	uint8 remote_ip[4];  // Remote host ip Address 
} esp_udp;

2. Next, we need to assign values to the network connection structure , Here we set it to udp There are two ways to communicate

Law 1 ： Create a udp Communication structure , And will udp The pointer of the communication structure is assigned to the network connection structure to store upd Members of the structure pointer

esp_udp ST_UDP;	// UDP Communication structure 


ST_NetCon.proto.udp = &ST_UDP;

Law two :    ST_NetCon.proto.udp = (esp_udp *)os_zalloc(sizeof(esp_udp));    // Application memory
 sizeof(esp_udp) :  Calculation udp Size of communication structure

os_zalloc(sizeof(esp_udp)): Distribute udp Communication structure size memory

(esp_udp *) ： Force the first address of this memory to udp Communication structure pointer type

Then assign the value to the network connection structure to store udp Members of the communication structure

•void * os zalloc (sizet size)
Apply for a piece of specified size ( Parameter determination ) Of memory , And return the first address of this memory .
Be careful ： After applying for this memory , Cannot be assigned to other variables . If there are too many operations to apply for memory , Memory will run out .
Use 【os_free( Pointer parameter ）】 To free up this memory .

Next we need to udp Assignment of communication structure  

There is no need to set goals here IP/ port (ESP8266 As Server, There is no need to know in advance Client Of IP/ port )

	//ST_NetCon.proto.udp->local_port  = espconn_port();	//  obtain 8266 Available ports 
	ST_NetCon.proto.udp->local_port  = 8266 ;		//  Set local port  // hold 8266 Port set to 8266
	//ST_NetCon.proto.udp->remote_port = 8888;		//  Set the target port 
	//ST_NetCon.proto.udp->remote_ip[0] = 192;		//  Set the target IP Address 
	//ST_NetCon.proto.udp->remote_ip[1] = 168;
	//ST_NetCon.proto.udp->remote_ip[2] = 4;
	//ST_NetCon.proto.udp->remote_ip[3] = 2;

 3. register / Define callback function

ESP8266_WIFI_Recv_Cb_JX(void * arg, char * pdata, unsigned short len)

Parameter one void* The pointer , Parameter 2 network transmission data pointer , Parameter 3 is data length

	espconn_regist_sentcb(&ST_NetCon,ESP8266_WIFI_Send_Cb_JX);	//  Register the callback function for sending network data successfully 
	espconn_regist_recvcb(&ST_NetCon,ESP8266_WIFI_Recv_Cb_JX);	//  Register the callback function for successful network data reception 

//  Callback function that successfully receives network data 【 Parameters 1： Network transmission structure espconn The pointer 、 Parameters 2： Network transmission data pointer 、 Parameters 3： Data length 】
void ICACHE_FLASH_ATTR ESP8266_WIFI_Recv_Cb_JX(void * arg, char * pdata, unsigned short len)
{
	struct espconn * T_arg = arg;		//  Cache network connection structure pointer 

	remot_info * P_port_info = NULL;	//  Remote connection information structure pointer 

	//  Set according to the data LED Liang Liang / destroy    Control the light on and off according to the first character of the received data 
	//-------------------------------------------------------------------------------
	if(pdata[0] == 'k' || pdata[0] == 'K')	LED_ON;			//  The initial is 'k'/'K', Light on 
	else if(pdata[0] == 'g' || pdata[0] == 'G')	LED_OFF;	//  The initial is 'g'/'G', The light goes out 
	os_printf("\nESP8266_Receive_Data = %s\n",pdata);		//  The serial port prints the received data 


	//  Get remote information 【UDP Communication is connectionless , When responding to the remote host, you need to obtain the other party's IP/ Port information 】
	//------------------------------------------------------------------------------------
	if(espconn_get_connection_info(T_arg, &P_port_info, 0)==ESPCONN_OK)	//  Get remote information 
	{
		T_arg->proto.udp->remote_port  = P_port_info->remote_port;		//  Get the opposite port number 
		T_arg->proto.udp->remote_ip[0] = P_port_info->remote_ip[0];		//  Get each other IP Address 
		T_arg->proto.udp->remote_ip[1] = P_port_info->remote_ip[1];
		T_arg->proto.udp->remote_ip[2] = P_port_info->remote_ip[2];
		T_arg->proto.udp->remote_ip[3] = P_port_info->remote_ip[3];
		//os_memcpy(T_arg->proto.udp->remote_ip,P_port_info->remote_ip,4);	//  Memory copy 
	}

	//--------------------------------------------------------------------
	OLED_ShowIP(24,6,T_arg->proto.udp->remote_ip);	//  Displays the remote host IP Address 
	//--------------------------------------------------------------------

	espconn_send(T_arg,"ESP8266_WIFI_Recv_OK",os_strlen("ESP8266_WIFI_Recv_OK"));	//  Send a reply to the other party 
}

espconn_get_connection_info(T_arg, &P_port_info, 0)

Parameter one ： Successfully received the pointer passed by the parameter of the network data callback function

Parameter two ： Is the pointer of the remote connection information structure pointer

Parameter 3 ： Set to 0

		T_arg->proto.udp->remote_ip[0] = P_port_info->remote_ip[0];		//  Get each other IP Address 
		T_arg->proto.udp->remote_ip[1] = P_port_info->remote_ip[1];
		T_arg->proto.udp->remote_ip[2] = P_port_info->remote_ip[2];
		T_arg->proto.udp->remote_ip[3] = P_port_info->remote_ip[3];

You can use this API To replace the top four lines os_memcpy(T_arg->proto.udp->remote_ip,P_port_info->remote_ip,4);    // Memory copy  

os_memcpy(void *des, void *src, size_t  n)

From the original memory pointer （ Parameter two ） Point , The length will be specified （ Parameter 3 ） data , Copy to target memory pointer （ Parameter one ） Point

void *des  Target memory block pointer

void *src  Source memory block pointer

size_n    Copy length

4. call UDP initialization API 

	espconn_create(&ST_NetCon);	//  initialization UDP signal communication 

Callback function for successfully sending network data

void ICACHE_FLASH_ATTR ESP8266_WIFI_Send_Cb_JX(void *arg)
{
	os_printf("\nESP8266_WIFI_Send_OK\n");
}