Intelligent fire alarm system circuit module design

Using the microcontroller MSP430F149 as the main control chip, an intelligent fire alarm system with high precision, high integration and ultra-low power consumption is designed. Using ambient temperature and smoke concentration as the basis for judging fire, the early warning of fire is completed. It is mainly composed of microcontroller 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 this system uses MSP430F149 as the lower computer to complete data collection, preprocessing and control of on-site devices, and uses the PC as the upper computer to complete various complex data processing and control of the microcontroller. The designed intelligent fire alarm system has high reliability, stability, accuracy, and high sensitivity to different types of fires, achieving the purpose of reducing the false alarm rate.

Temperature measurement module: The design adopts the DS18B20 temperature sensor that supports the "one-line bus" interface, has strong anti-interference, simple external circuit, and high accuracy for real-time measurement of temperature. 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 emits an alarm indication sound when the microprocessor determines that there is a fire. Due to the limited I/O port driving capability of the microcontroller, a PNP transistor 2N5401 is selected to form a transistor driving circuit to drive the piezoelectric buzzer.

Sound and light alarm module diagram

LCD display module: Display time, measured temperature, smoke concentration and other parameters on the LCD module so that we can more conveniently read the current temperature value and smoke concentration value.

LCD module diagram

Serial communication module: This design uses MSP430F149 as the slave computer and PC as the host computer. Data is transmitted to the PC through RS-232, so that we can monitor various measurement parameters more conveniently. The serial interface is a device that can convert parallel data characters received from the CPU into a continuous serial data stream and send them out, and at the same time, it can convert the received serial data stream into parallel data characters and supply them to the CPU. Generally, the circuit that completes this function is called a serial interface circuit. The circuit diagram is as follows:

Serial communication circuit

Clock module: DS1302 is a trickle charging clock chip launched by DALLAS. It contains a real-time clock/calendar and 31 bytes of static RAM. It communicates with the microcontroller through a simple serial interface. The real-time clock/calendar circuit provides seconds, minutes, hours, and days. , date, month, and year information. The number of days in each month and the number of days in leap years can be automatically adjusted. The clock operation can be determined by AM/PM instructions to adopt 24 or 12 hour format. The DS1302 and the microcontroller can simply communicate in a synchronous serial manner, using only three port lines: RES reset, I/O data line, and SCLK serial clock.

Clock circuit

Review analysis:

Traditional fire alarm systems have problems such as simple structure, low accuracy, false alarms and missed alarms. To address these problems of fire alarm systems in smart buildings, the intelligent fire alarm system based on MSP430F149 has high reliability and stability. , high accuracy. Taking the single-chip computer MSP430F149 as the core and using the ambient temperature and smoke concentration as the basis for judging fire, the early warning of fire is completed. It is mainly composed of microcontroller control module, clock module, smoke concentration measurement module, DS18B20 temperature measurement module, sound and light alarm module, 1602 LCD module and power supply.