Question

Create a high-level design for a home alarm system. Assume that there are 4 windows and 2 doors. The windows and doors have light sensors, so if any object crosses the light path, an appropriate event will be registered. Also, each window and door has latches with sensors that detect if the latch has been turned.

Your solution will consist of the following parts

1.       Use a variable “Armed” to allow a user to arm the alarm system. So if a user is at home, the alarm is disarmed.

2.       Create appropriate variables that will capture the state of the windows and doors. (2 points)

3.       Create a flowchart that will process the sensed input. (2 points)

4.       Design the right output. (2 points)

5.       Create a mechanism to reset the alarm. (1 point)

6.       Write pseudo-code (e.g. code that looks like C), using any functions you may create. 

Answer 1

1. We will use Armed variable as 1 or 0, 1- Activated & 0- Deactivated.

2. Following are the variables we will be using to represent the status of latches and the Light sensors if particular doors and windows.

All the variables used are of type enumeration that is they can only take specified values 1 or 0.

Entity	Latch Variable	Light Sensor
Door1	D_Latch1	D_Ls1
Door2	D_Latch2	D_Ls2
Window1	W_Latch1	W_Ls1
Window2	W_Latch2	W_Ls2
Window3	W_Latch3	W_Ls3
Window4	W_Latch4	W_Ls4

The Following is the flowchart

In the output we will print the name of the window or the door where an unappropriate activity is happened, that is the light sensor is being cut.

The Pseudocode can be given as:

1. Start
2. Set all the latches and Light Sensors.
3. If(D_Ls1,D_Ls2 OR W_Ls1 OR W_Ls2 OR W_Ls3 OR W_Ls4 ==1)
4. {
5. if(Armed==1)
6. {
7. SET Alarm=1;
8. print("Enter 0 to turn off the alarm");
9. if(input==0)
10. {
11. SET Alarm=0;
12. }
13. }
14. }
15. if (D_Ls1==1)
16. {Print("Unappropriate activity at door1");}
17. if (D_Ls2==1)
18. {Print("Unappropriate activity at door2");}
19. if (W_Ls1==1)
20. {Print("Unappropriate activity at Window1");}
21. if (W_Ls2==1)
22. {Print("Unappropriate activity at Window2");}
23. if (W_Ls3==1)
24. {Print("Unappropriate activity at Window3");}
25. if (W_Ls4==1)
26. {Print("Unappropriate activity at Window4");}
27. END