I read on www.freertos.org website while looking for information on PIC18F452 porting: […] "Includes the standard minimal "integer" and "pollQ" tasks, along with a "check" task that periodically checks the other tasks are operating without error, and flashes an LED accordingly. To ensure the target is not unexpectedly resetting a single "X" is transmitted from the USART when the application boots. When operating correctly RTOSDemo1 will cause LED 1 to toggle every second. If an error has occurred in any task the toggle rate will increase to 100ms." […] What does it mean? My PIC18F452 could reset unexpectedly also if there are no errors in code? Thank you in advance, Pietro

The key word is "unexpectedly".  You would not expect the device to reset, the ‘X’ is transmitted so you can check that this is the case by monitoring the UART output. Regards.