如何在嵌入式设备上通过 UDP 接收数据

Question

currently I am working on a UDP-Client Script for a Mbed Project. I work with the B-L475E-IOT01A development board and want to recieve data from another network device.

The sending side (on another device) works. I tested it with a python script on my computer.

I have the following problem: I can establish conection to the network and I can initialize a UDP socket with the open() function. My problem is, that if I try to bind() the socket to either a port or a socket address I get the nsapi_error_t code -3002 , which means "unsopported functionality". Here is the code:

#include "UDPSocket.h"
#include "mbed.h"

const char SSID[] = "";
const char password[] = "";
const uint16_t Port = 37020;

UDPSocket socket;
WiFiInterface *wifi;
BufferedSerial pc(USBTX, USBRX, 115200);

int main() {
  pc.set_format(8, SerialBase::None, 1);

  wifi = WiFiInterface::get_default_instance();
  if (!wifi) {
    printf("ERROR: No WiFiInterface found.\n");
    return -1;
  }

  printf("\nConnecting to %s...\n", SSID);
  int ret = wifi->connect(SSID, password, NSAPI_SECURITY_WPA2);
  if (ret != 0) {
    printf("\nConnection error: %d\n", ret);
    return -1;
  }

  SocketAddress a;
  wifi->get_ip_address(&a);
  printf("IP: %s\n", a.get_ip_address());

  int returnable = 1;
  while (returnable != 0) {
    returnable = socket.open(wifi);
    printf("%d\r\n", returnable);
    wait_us(500000);
  }

  returnable = 1;
  while (returnable != 0) {
    returnable = socket.bind(Port);
    printf("%d\r\n", returnable);
    wait_us(500000);
  }

  while (1) {
    char message[500];
    int n = socket.recv(&message, sizeof(message));
    printf("%d\r\n", n);
    printf("%s", message);
    wait_us(100000);
  }
  wifi->disconnect();

  printf("\nDone\n");
}

I deleted the wifi data for safaty reasons. Here is the output:

Connecting to ...
IP: 192.168.178.25
0
-3002

My question is, why I cant bind my board to a specific port. Do you have any ideas? Thank you in advance.

Answer 1

MBED declares socket.bind as bind (const Host &me) . The argument is not a port number, but a Host instance. Change it to

sock.bind(Host(IpAddr(), port));