I got a PC freertos simulation that looks OK, but after running for a few hours, it freezes. I set breakpoints in all tasks, and no BP is hit, the only running loop is the prvSimulatedPeripheralTimer (), infinite for(;;) loop. Any ideas that will help debugging this will be appreciated. Thanks. Johanan

Is this using the FreeRTOS Windows port, which is often referred to as the Windows simulator, or is it a simulation you have created yourself?

Using FreeRTOS windows port. Thanks

Are you using any Windows system calls, such as printf, or WinSocks? Those are known to cause issues, although there are workarounds.

Also, we have noticed strange behaviour when calling rand(), so will provide our own version if it is necessary.

Regards.

Using winsoc for UDP. Actually the simulation is used as development for the STM32F4 target. The same code is used (using compiler #ifdef whenever necessary) for the PC simulation and target. All I/O hardware done by functions calls. In the simulation, it sends and receives UDP packets to an Arduino that activates all I/O, while the target uses the same function calls for real I/O. If the problem is with the UDP socket, then I don't mind too much, as this is just a simulation. How can I verify this? My current strategy is to comment out functions, until the one that creates the problem will be found. Whoever this takes a very long time...

If you download the FreeRTOS+TCP source code (http://www.freertos.org/tcp) you will see how we get around this.

Some of the demos use FreeRTOS+TCP sockets to communicate with WinSock sockets. To do that reliably all use of the WinSock API is done inside standard Windows threads (as opposed to Windows threads that are under the control of the FreeRTOS scheduler). The standard Windows threads then use a stream buffer (thread safe circular buffer with no system calls) to pass data to and from the FreeRTOS tasks. The key is not to have Windows system calls in FreeRTOS tasks themselves.

Yep, commenting out the UDP removed the problem, now I'll do the workaround. Thanks agian, many hours saved....

Just by running that UDP task from windows thread with _beginthread ( ) , and communicating to FreeRTOS via a buffer fixed all these issues. Thanks again.