1 An automatic door at a store has a sensor in front A1 and

1. An automatic door at a store has a sensor in front (A1) and behind (A0). The door opens (B0=1) when a person approaches from the front, and stays open as long as a person is detected in front or behind. If the door is closed and a person approaches from the behind, the door does not open. If the door is closed and a person approaches from the front but a person is also detected behind, the door does not open, to prevent hitting the person that is behind.

2. An amusement park ride has sensor mats on the left (A0) and right (A1) of a ride car. A ride operator starts the ride by pressing a button (A7); each unique press toggles the ride from stopped to started (B0=1) and vice-versa. If anyone leaves the ride car and steps on a sensor mat, the ride stops and an alarm sounds (B1=1). The alarm stops sounding when the person gets off the sensor mat. The only way for the ride to restart is for the operator to press the button again. The ride never starts if someone is on the sensor mat.

Solution

Example 1 )   

#define front_sensor   A0 // it will define front sensor as integer //

#define behind_sensor A1 // it will define back sensor as integer //

#define open_door      B0=1 // it will put value 1 if door is open //

#define close_door     B0=0 // it will put value 0 if door is closed //

#define is_door_open   B0

#define is_door_closed (B0==0)

#define running 1

int main()

{

  // example

  while(running)

  {

    if(is_door_closed)

    {

      if(front_sensor)

      {

        open_door;

      }

    }

  } // while running

  return 0;

}