ESP32 TCP客户端

int create_ipv4_socket()
{
  struct addrinfo hints;
  struct addrinfo *res;
  struct in_addr *addr;

  hints.ai_family = AF_INET;
  hints.ai_socktype = SOCK_STREAM;

  int err = getaddrinfo(UDP_IPV4_ADDR, TCP_PORT, &hints, &res);

  if(err != 0 || res == NULL) {
    printf("DNS lookup failed err=%d res=%p\n", err, res);
    return -1;
  }

  /* Code to print the resolved IP.

     Note: inet_ntoa is non-reentrant, look at ipaddr_ntoa_r for "real" code */
  addr = &((struct sockaddr_in *)res->ai_addr)->sin_addr;
  printf("DNS lookup succeeded. IP=%s\n", inet_ntoa(*addr));

  l_sock = socket(res->ai_family, res->ai_socktype, 0);
  if(l_sock < 0) {
    printf("... Failed to allocate socket.\n");
    freeaddrinfo(res);
    return -1;
  }

  struct timeval to;
  to.tv_sec = 2;
  to.tv_usec = 0;
  setsockopt(l_sock,SOL_SOCKET,SO_SNDTIMEO,&to,sizeof(to));

  if(connect(l_sock, res->ai_addr, res->ai_addrlen) != 0) {
    printf("... socket connect failed errno=%d\n", errno);
    close(l_sock);
    freeaddrinfo(res);
    return -1;
  }

  printf("... connected\n");
  freeaddrinfo(res);

  // All set, socket is configured for sending and receiving
  return l_sock;
}

来自此论坛 https://www.esp32.com/viewtopic.php?t=5965

您如何与ESP沟通?如果您通过UART进行通信,只需在UART端口上写下所需的命令即可发送给他:

“AT+CIPSTATUS\r\n” 然后等待他的回应。

如果您直接用计算机连接到ESP32,只需使用putty并直接向其发送AT命令即可。

AT命令的非详尽列表可在此处找到: https://www.espressif.com/sites/default/files/documentation/esp32_at_instruction_set_and_examples_en.pdf