Alarm research in fire alarm system based on digital temperature sensor alarm search

In order to predict the danger of fire, fire alarm system is designed based on single chip microcomputer AT89S51. The environment temperature can be monitored by digital temperature sensor. This paper describes the alarm search of digital temperature sensor based on many I/O ports. The structure of the scratchpad is illustrated. The Format of high and low alarm trigger TH and TL register and temperature register are described in detail. Writing scratchpad command and copying scratchpad command can keep alarm trigger register TH ,TL and configuration register unchanged in the status of power-down. The value of TH and TL can be defined by user. Amendment alarm high limit can be carried out by keyboard or the command that is sent by computer. The pivotal programs of alarm searching and alarm processing are given out. The experiment illustrates that fire alarm system can realize alarm accurately and in time.