From what I read from the mailing list, the timer system is supposed to work, however, it didn't work on my system, and because of that, I wrote a separate thread to regularly check the timeout values and decrease them. The system seems working fine until I start to test TCP part of the code. I have about 20% success rate in establish a TCP connection with a server, and 80% failure, and I am suspecting maybe my timer thread is causing that problem. So I am just curious to know, how do I run the native timer system in lwip stack without introducing an outside mechanism? I learned someone is using sys_msleep function call, but that seems would stall my process. If anyone could give me a brief sample example on how to run the lwip timer, I would greatly appreciate your time and help.