This program exercises the motor. The motor is rotated in a clockwise direction and the number of revolutions is displayed on Display 0 (the 7-segment display). The display only shows up to nine revolutions and then resets.
The motor sensor is connected to P3.5, which is the external clock source for timer 1. Therefore, timer 1 is put into event counting mode. In this way, the the timer increments once every motor revolution.
The value in timer 1 low byte is moved to A and this value together with the data pointer (DPH and DPL) are used to get the 7-segment code from program memory. The code is then sent to P1 to put the appropriate number on the Display 0.
The motor can be changed from clockwise to anti-clockwise by pressing SW0 (on P2.0). The motor direction is stored in F0 (1 for clockwise, 0 for anti-clockwise). The value in F0 is sent to Display 0's decimal point (P1.7). This indicates the motor's direction - if the decimal point is lit, the motor is rotating anti-clockwise, while if it is not lit the motor is rotating clockwise.
The value in F0 is compared with the value of SW0. If they are the same the motor direction does not need to be changed. If they are not the same it means the user has pressed SW0 and the motor direction must be reversed. When this happens the new motor direction is then stored in F0.
