Intelligent fire alarm system circuit module design

L0504-Murata muRata common mode inductor 90Ω 150mA

With the single-chip MSP430F149 as the main control chip, a high-precision, high-integration, ultra-low-power intelligent fire alarm system is designed. The ambient temperature and the smoke concentration were used as the basis for judging the fire, and the fire warning was completed. Mainly composed of single-chip control module, clock module, smoke concentration measurement module, DS18B20 temperature measurement module, sound and light alarm module, 1602 liquid crystal display module and power supply. And the system uses MSP430F149 as the lower computer to complete data acquisition, pre-processing and control of the field device. The PC is used as the host computer to complete various complicated data processing and control of the single-chip microcomputer. The designed intelligent fire alarm system has high reliability, stability and high accuracy, and has high sensitivity to different types of fires, achieving the purpose of reducing the false alarm rate.
Temperature measurement module: The design uses real-time measurement of temperature by DS18B20 temperature sensor which supports "first-line bus" interface, strong anti-interference, simple external circuit and high precision. Among them, DS18B20 pin 2, DQ, is connected to the P2.0 pin of MSP430F149, as shown in the figure.

Temperature measurement sound and light alarm module: The buzzer sounds an alarm indicating sound when the microprocessor determines that it is a fire. Due to the limited I/O port driving capability of the microcontroller, the PNP transistor 2N5401 is used to form a transistor driving circuit to drive the piezoelectric buzzer.

Sound and light alarm module diagram LCD display module: display time, temperature measurement, smoke concentration and other parameters on the liquid crystal module, so that we can more easily read the current temperature value and smoke concentration value.

LCD module module serial communication module: This design uses MSP430F149 as the lower computer, PC as the upper computer, through RS-232 to transfer data to the PC, we can more easily monitor the various measurement parameters. The serial interface is a device that can convert parallel data characters from the CPU into a continuous serial data stream and convert the received serial data stream into parallel data characters for the CPU. The circuit that generally accomplishes this function is called a serial interface circuit. The circuit diagram is as follows:

Serial communication circuit clock module: DS1302 is a trickle charge clock chip from DALLAS. It contains a real-time clock/calendar and 31-byte static RAM. It communicates with the microcontroller through a simple serial interface. The real-time clock/calendar circuit provides seconds, minutes, and Information on hours, days, dates, months, and years The number of days per month and the number of days in leap years can be automatically adjusted. The clock operation can be determined by the AM/PM indicator in 24- or 12-hour format. The DS1302 and the microcontroller can communicate in a simple synchronous serial mode using only three port line RES resets, I/O data lines, and SCLK serial clocks.

Clock circuit evaluation analysis:
The traditional fire alarm system has the problems of simple structure, low accuracy, false alarms and false negatives. For the fire alarm system in intelligent buildings, the intelligent fire alarm system based on MSP430F149 has high reliability and stability. High accuracy. Taking the MSP430F149 as the core, the ambient temperature and smoke concentration are used as the basis for judging the fire, and the fire warning is completed. Mainly composed of single-chip control module, clock module, smoke concentration measurement module, DS18B20 temperature measurement module, sound and light alarm module, 1602 liquid crystal display module and power supply.