ABSTRACT
he design is mainly composed of temperature and hunudity detection, smoke detection circuit, alarm circuit,
display circuit and human detection module. Tlie temperanire and humidity test section uses die DHT11 temperature
and hiumdity sensor. DHT11 is a single bus digital temperature and humidity sensor. It has the advantages of small
error, high resolution, strong anti interfbi:ence ability and so on. In tlie smoke detection circuit module, the gas
sensor MQ-2 and die ADC0832 analog to digital converter are used to realize the basic fimctions. Through these
sensors and chips
、
when the combustible gas concentration in die environment or toxic gas changes the system sends
out die correspondmg light alarm signal and sound alarm signal, m order to realize the mtelligeiit fire alarm prompt.
Tlie human detection part is realized by the HC-SR501 module. The mam principle is to convert the mfrared radiation
signals into electrical signals, tlieii amplify and output them. If a dangerous signal is detected, the signal is transmitted
to the microcontroller, processed by a microcontroller, and then controlled by a biizzer and LED to light a warning.
The design can also be applied in a variety of anti-theft occasions, such as home security, warehouse anti-
tlieft, etc.. Temperature, humidity, smoke and human burglar detection are the tliree basic environmental parameters,
and their measurement methods and devices are unportant to the present life and production.
Keywords： Temperature and humidity detection; MQ-2 sensor; Smoke alarm; Pyroelectric infrared sensor;
Burglar alarm
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