#include "mbed.h"
#include "EthernetInterface.h"

Serial pc (USBTX,USBRX);

void SocketThread(void const* args)
{
   int aSocket;
   aSocket = lwip_socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE);
   if (aSocket < 0)
      pc.printf("-");
   else
      pc.printf("+");
   while (true) osDelay(1001);
}

osThreadDef(SocketThread, osPriorityNormal, 512 );

static EthernetInterface interface;

int main()
{   
   pc.printf("\r\nHello netTest \r\n");
   interface.init("172.16.2.162", "255.255.252.0", "0.0.0.0");
   interface.connect();

   osThreadId tid[16];
   for (int i=0; i<8; i++)
   {
      tid[i] = osThreadCreate(osThread(SocketThread), (void*) i);
      if (tid[i] == NULL) pc.printf("Failed to create a thread #%d \r\n", i);
      osDelay(50);
   }
   
   pc.printf("\r\ndone \r\n");
   while (true) wait(1.0);
}

Hi there, my application needs at least 3 UDP sockets and I'm having trouble with it, I cannot create more than 3 sockets. I also found a post in the questions section, where someone reports the same with 3 TCP connections. I made a small test program that attempts to start a thread, and inside the thread I call lwip_socket(AF_INET, SOCK_DGRAM, 0) - it works for 3 sockets, then fails. After digging into the depths of the lwip things, I think the function tcpip_apimsg() fails, when it calls sys_mbox_valid(&mbox). I do not yet understand what this code does, "mbox" is a static variable, so why would the code work 3 times and then fails. Can anyone confirm this behaviour ? Or is there anyone with more than 3 sockets ? <<code title=sample code>> #include "mbed.h" #include "EthernetInterface.h" Serial pc (USBTX,USBRX); void SocketThread(void const* args) { int aSocket; aSocket = lwip_socket(AF_INET, SOCK_DGRAM, IPPROTO_UDPLITE); if (aSocket < 0) pc.printf("-"); else pc.printf("+"); while (true) osDelay(1001); } osThreadDef(SocketThread, osPriorityNormal, 512 ); static EthernetInterface interface; int main() { pc.printf("\r\nHello netTest \r\n"); interface.init("172.16.2.162", "255.255.252.0", "0.0.0.0"); interface.connect(); osThreadId tid[16]; for (int i=0; i<8; i++) { tid[i] = osThreadCreate(osThread(SocketThread), (void*) i); if (tid[i] == NULL) pc.printf("Failed to create a thread #%d \r\n", i); osDelay(50); } pc.printf("\r\ndone \r\n"); while (true) wait(1.0); } <</code>>