IAR PowerPac RTOS User Guide

DebuggingRuntime errorsSome error conditions can be detected during runtime. These are:● Usage of uninitialized data structures● Invalid pointers● Unused resource that has not been used by this task before● OS_LeaveRegion() called more often than OS_EnterRegion()● Stack overflow (this feature is not available for some processors)Which runtime errors that can be detected depend on how much checking is performed. Unfortunately, additionalchecking costs memory and speed (it is not that significant, but there is a difference). If IAR PowerPac RTOS detectsa runtime error, it calls the following routine:void OS_Error(int ErrCode);This routine is shipped as source code as part of the module OS_Error.c. It simply disables further task switches andthen, after re-enabling interrupts, loops forever as follows:Example/*Run time error reaction*/void OS_Error(int ErrCode) {OS_EnterRegion(); /* Avoid further task switches */OS_DICnt =0; /* Allow interrupts so we can communicate */OS_EI();OS_Status = ErrCode;while (OS_Status);}When using an emulator, you should set a breakpoint at the beginning of this routine or simply stop the program aftera failure. The error code is passed to the function as parameter.You can modify the routine to accommodate your own hardware; this could mean that your target hardware sets anerror-indicating LED or shows a little message on the display.Note:When modifying the OS_Error() routine, the first statement needs to be the disabling of scheduler viaOS_EnterRegion(); the last statement needs to be the infinite loop.If you look at the OS_Error() routine, you will see that it is more complicated than necessary. The actual error codeis assigned to the global variable OS_Status. The program then waits for this variable to be reset. Simply reset thisvariable to 0 using your in circuit-emulator, and you can easily step back to the program sequence causing the problem.Most of the time, looking at this part of the program will make the problem clear.PPRTOS-2 123