Main program running when workpiece is ready on deferent belt(deferent_ready=ture).
* Call Square_Wave subroutine to generate 0.5ms square wave on P1.2 to drive
* electromotor,then drive deferent belt step forward. When it steps to the measure
* zone, it stops to be measured. Then call A_D subroutine to transform analog
* signals to digital signals , after then call serial subroutine to transfer
* digital signals to PC. Call square wave subroutine to drive deferent belt step to
* original position waitting for defere ready flag to run the next circle.
