tailieunhanh - Seminar 9: Case Study: Intruder Alarm System

System Operation: When initially activated, the system is in ‘Disarmed’ state. In Disarmed state, the sensors are ignored. The alarm does not sound. The system remains in this state until the user enters a valid password via the keypad (in our demonstration system, the password is “1234”). When a valid password is entered, the systems enters ‘Arming’ state. In Arming state, the system waits for 60 seconds, to allow the user to leave the area before the monitoring process begins. . | Seminar 9 Case Study Intruder Alarm System Copyright Michael J. Pont 2001-2006. Contains material from Pont . 2002 Embedded C Addison-Wesley. PES I - 241 Introduction Copyright Michael J. Pont 2001-2006. Contains material from Pont . 2002 Embedded C Addison-Wesley. PES I - 242 System Operation When initially activated the system is in Disarmed state. In Disarmed state the sensors are ignored. The alarm does not sound. The system remains in this state until the user enters a valid password via the keypad in our demonstration system the password is 1234 . When a valid password is entered the systems enters Arming state. In Arming state the system waits for 60 seconds to allow the user to leave the area before the monitoring process begins. After 60 seconds the system enters Armed state. In Armed state the status of the various system sensors is monitored. If a window sensor is tripped the system enters Intruder state. If the door sensor is tripped the system enters Disarming state. The keypad activity is also monitored if a correct password is typed in the system enters Disarmed state. In Disarming state we assume that the door has been opened by someone who may be an authorised system user. The system remains in this state for up to 60 seconds after which - by default - it enters Intruder state. If during the 60-second period the user enters the correct password the system enters Disarmed state. In Intruder state an alarm will sound. The alarm will keep sounding indefinitely until the correct password is entered. Copyright Michael J. Pont 2001-2006. Contains material from Pont . 2002 Embedded C Addison-Wesley. PES I - .