Quality RTOS & Embedded Software

 Real time embedded FreeRTOS RSS feed 
Quick Start Supported MCUs PDF Books Trace Tools Ecosystem


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,

[ Back to the top ]    [ About FreeRTOS ]    [ Privacy ]    [ Sitemap ]    [ ]

Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.

Latest News

FreeRTOS v10.2.1 is available for immediate download. MIT licensed, includes 64-bit RISC-V, NXP Cortex-M33 demo & Nuvoton Cortex-M23 demo.

NXP tweet showing LPC5500 (ARMv8-M Cortex-M33) running FreeRTOS.

View a recording of the "OTA Update Security and Reliability" webinar, presented by TI and AWS.


FreeRTOS and other embedded software careers at AWS.

FreeRTOS Partners

ARM Connected RTOS partner for all ARM microcontroller cores

Cadence Tensilica Cortes

Espressif ESP32

IAR Partner

Microchip Premier RTOS Partner

RTOS partner of NXP for all NXP ARM microcontrollers





STMicro RTOS partner supporting ARM7, ARM Cortex-M3, ARM Cortex-M4 and ARM Cortex-M0

Texas Instruments MCU Developer Network RTOS partner for ARM and MSP430 microcontrollers

OpenRTOS and SafeRTOS

Xilinx Microblaze and Zynq partner