Embebbed IDE Link and overrun notification

I am using Embebbed Coder to compilate a simulink code into a Texas Instruments Microcontroller (Delfino 28335 MCU). I am executing a set of instructions (basicly several PID controllers, analog inputs and PWM outputs) in discrete time with fixed-step (50 microsecons). I would would like to get a flag (switch on a led) if the microcontroller could not executate all the instruction in 50 us.

 I use Embebbed Coder IDE Link to generates the executable file (*.out). In simulink/configuration_parameters/code_generation/Code_target there is an option to create a "call custom fucntion" which is called when an averrun is detected. I think this function is called when the execution time overtake the set fixed-time value in discrete time.

I would like to switch on a led when an overrun is detected. Could you give some tips to create that "custom function" (for exampple where I have to declarate the fucntion in matlqab/simulink or if there is any simulink/block to do it)?

Thanks in advance,

Manuel