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Start lwIP UDP in a Task

Posted by Mathias Zenger on April 16, 2009

I've been trying for hours to run a simple UDP example from the lwIP documentation in a FreeRTOS task.

My application does not return from the method call netconn_connect(). Although it is likely to be a lwIP problem I am not sure if I can use the netconn/netbuf methods in FreeRTOS.

Does anybody have experience with this? Is there an example available which also uses netconn_recv()?

The task function looks as follows:

portTASK_FUNCTION(vNTPClient, pvParameters) {
struct netconn *conn;
struct netbuf *buf;
struct ip_addr addr;
char *data;
char text[] = "A static text";
int i;

portTickType xLastWakeTime;
// Initialize with current tick count
xLastWakeTime = xTaskGetTickCount();

// Task loop
for (;;) {
// Check if interface is ready
if (netif_is_up(&MACB_if)) {
/* create a new connection */
conn = netconn_new(NETCONN_UDP);
/* set up the IP address of the remote host */
addr.addr = htonl(0x0a000001);
/* connect the connection to the remote host */
netconn_connect(conn, &addr, 7000);
/* create a new netbuf */
buf = netbuf_new();
data = netbuf_alloc(buf, 10);
/* create some arbitrary data */
for(i = 0; i < 10; i++)
data = i;
/* send the arbitrary data */
netconn_send(conn, buf);
/* reference the text into the netbuf */
netbuf_ref(buf, text, sizeof(text));
/* send the text */
netconn_send(conn, buf);
/* deallocate connection and netbuf */
else {
print_dbg("Waiting for IP...\n");
// Delay the task
vTaskDelayUntil(&xLastWakeTime, ntpclientTICK_RATE);

Thanks for your help. Regards,

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