DEMO91
   Demonstration for use Timer functions.
   use CountDownTimer channel 0 for LED ON/OFF
   function used:
     TimerOpen --> begin to use I-7188 timer
     TimerClose --> stop to use timer
     CountDownTimerStart  --> start to countdown a time interval
     CountDownTimerReadValue -->to decide if time is up.
   Use CountDownTimer to count 500ms(0.5s) to turn LED ON or OFF.
   press 'q' to quit program.