How to use AT89S51 microcontroller to realize the design of home voice alarm system

The power supply of this system consists of two parts: mains power and backup battery. Under normal circumstances, the mains power supplies DC power to the alarm system through rectification, filtering, and voltage stabilization, and automatically stabilizes the charging of the battery. When the mains power fails, the battery is automatically put into use to ensure that the alarm system can work normally and at the same time, power failure warning information is sent to the outside world.

System software design

The basic task of software design is to realize the programmability of user security functions and real-time monitoring and alarming of warning zones. This software design adopts structured programming method. The main work in the software design is to complete the processing of the digital signal VO2 output by the infrared sensing signal processor BISS0001 by the microcontroller, the software implementation of the voice service and the timely voice recording and playback. The software design flow chart is shown in Figure 7.

The BISS0001 chip has performed anti-interference processing on the signal from the sensor and obtained the signal VO2. In order to improve the reliability of system detection, VO2 is further processed with a microcontroller. When programming the voice chip 1420, write it according to its working process. When recording, press and hold the "REC" button until the indicator light turns on, and you can speak to the microphone on the board to record. When you release the button, the recording stops and forms a segment. During playback, press the "PE" button to play the entire recording, and the playback will automatically stop after the end of the recording. Press and hold the "PL" key to play, release the key to stop. The address line of ISD1420 has 8 bits, and 6 bits are connected to the I/O port of AT89S51. The minimum length of each voice segment is 125ms. Each voice segment can be output controlled by an address line. Every 125ms is an address and is controlled by six address lines A2~A7. After each segment of the voice recorded by the user ends, the chip automatically sets an end-of-segment flag (EOM). When the chip is full, it sets an overflow flag (OVF). The microcontroller control circuit performs the playback operation according to the starting address of a certain segment. When the segment ends Mark (EOM) will automatically stop playing, and the microcontroller will start to trigger the starting address of the next segment of voice after receiving the end-of-segment mark (EOM). Such control can combine many different segments of speech into one sentence and play it out, realizing automatic combination of speech.

Conclusion

This system realizes the home voice alarm function. After many tests, the system works stably. Users can individually set different modes such as outgoing and do not disturb through the keyboard to realize voice service functions. The alarm system has the advantages of simple structure, low cost, novelty, etc., and is suitable for home use.