I am trying to run a RTC Calender example provided in ST Standard Peripheral Driver Library V3.1.2. I am able to run without enabling "Use MicroLib option in Tagret settings" in simulation mode but in debug mode it hangs at address "0x08000634" in _sys_open:. I have to enable "Use MicroLib" option to run on ST's STM3210E board. Can some one put some light on this issue?