AT+ CIPSEND issue

2016-03-03T00:34:37+08:00

Hi Guys,
I have recently purchased a esp8266 module ( NodeMCU v1.0) and have put in the AT firmware in the same.

I am able to open a UDP connection with my remote server and send data to it, using minicom or teraterm.

Now, I am trying to do the same in my C code, and successful till I get the '>' prompt in the console.
I am writing to the open filedescriptor, but looks like nothing gets sent to the remote but an empty string.

My relevant code snippet is as below

Code:

               /* Check if AT Interface is woring fine */
      snprintf(w_buf,PATH_MAX,"%s","AT\r\n");
                write(fd,w_buf,sizeof(w_buf));

                sleep(1);
      read(fd,r_buf,sizeof(r_buf));

                printf("%s\n",r_buf);
      
   /* Put the system in station mode */
      memset(w_buf,0,sizeof(r_buf));
      snprintf(w_buf,PATH_MAX,"%s","AT+CWMODE=1\r\n");   
                write(fd,w_buf,sizeof(w_buf));

                usleep(100000);
      memset(r_buf,0,sizeof(r_buf));
      read(fd,r_buf,sizeof(r_buf));
                printf("%s\n",r_buf);


      /* Connect to the WIFI */
      memset(w_buf,0,sizeof(r_buf));
      snprintf(w_buf,PATH_MAX,"%s","AT+CWJAP=\"vios-dlink24\",\"viosdlink24\"\r\n");   
      write(fd,w_buf,sizeof(w_buf));

                sleep(5);   /* Sleep for 5 seconds */
      memset(r_buf,0,sizeof(r_buf));
      read(fd,r_buf,sizeof(r_buf));

                printf("%s\n",r_buf);

      /* Check the IP */
      memset(w_buf,0,sizeof(r_buf));
      snprintf(w_buf,PATH_MAX,"%s","AT+CIFSR\r\n");   
                write(fd,w_buf,sizeof(w_buf));

                sleep(15);
      memset(r_buf,0,sizeof(r_buf));
      read(fd,r_buf,sizeof(r_buf));

                printf("%s\n",r_buf);

      /* Single connection mode */
      memset(w_buf,0,sizeof(r_buf));
      snprintf(w_buf,PATH_MAX,"%s","AT+CIPMUX=0\r\n");   
                write(fd,w_buf,sizeof(w_buf));

                sleep(1);
         memset(r_buf,0,sizeof(r_buf));
       read(fd,r_buf,sizeof(r_buf));

                printf("%s\n",r_buf);


      /* Open UDP port  */
      memset(w_buf,0,sizeof(r_buf));
      snprintf(w_buf,PATH_MAX,"%s","AT+CIPSTART=\"UDP\",\"192.168.1.35\",1112,1112,2\r\n");   
                write(fd,w_buf,sizeof(w_buf));

                sleep(1);
      memset(r_buf,0,sizeof(r_buf));
      read(fd,r_buf,sizeof(r_buf));

                printf("%s\n",r_buf);

      /* Send 5 bytes */
      memset(w_buf,0,sizeof(r_buf));
      snprintf(w_buf,PATH_MAX,"%s","AT+CIPSEND=5\r\n");   
                write(fd,w_buf,sizeof(w_buf));

                sleep(5);
      memset(r_buf,0,sizeof(r_buf));
      read(fd,r_buf,sizeof(r_buf));

                printf("%s\n",r_buf);

               write(fd,"Hello",5);

      /* Close the connection */
      memset(w_buf,0,sizeof(r_buf));
      snprintf(w_buf,PATH_MAX,"%s","AT+CIPCLOSE\r\n");   
                write(fd,w_buf,sizeof(w_buf));

                sleep(1);
      memset(r_buf,0,sizeof(r_buf));
      read(fd,r_buf,sizeof(r_buf));

                printf("%s\n",r_buf);

Now, the console output is as below

Code:

AT

OK

AT+CWMODE=1

OK

AT+CWJAP="vios-dlink24","viosdlink24"
WIFI DISCONNECT
WIFI CONNECTED
WIFI GOT IP

AT+CIFSR
busy p...

OK

AT+CIPMUX=0

OK

AT+CIPSTART="UDP","192.168.1.35",1112,1112,2
CONNECT

OK

AT+CIPSEND=5

OK
>
busy s...

Recv 5 bytes

SEND OK

AT+CIPCLOSE
CLOSED

OK

Now, what am I missing in here? How can i send the data after the '>' prompt comes.

Thanks
Biswa

Statistics: Posted by biswar — Thu Mar 03, 2016 12:34 am

ESP8266 Developer Zone

AT+ CIPSEND issue