This is a digital home security system with voice feature which can monitor room temperature, smoke, motion, and windows & doors. The system is fully digital and also be fully customized. It incorporated a 16×2 LCD display with a 4×4 keypad.
The goal of this project is to utilize the after-market parts and build an integrated home security system. Besides traditional magnetic switch equipped with doors and windows, we have also incorporated temperature sensor, smoke detectors, and motion sensor. Hence the security system will sound an alert when there is an attempt of the break-in or if there is possible smoke or fire.
The system is fully digital and also be fully customized. It incorporated a 16×2 LCD display with a 4×4 keypad. Each sensor can be enabled or disabled, and alarm frequency and skim can also be chosen by users. We have also equipped a voice playback chip, and it will speak which sensor has gone wrong.
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The hardest part of the program is timing. When any sensor goes wrong, the program will wait for certain seconds (set by a user), and then make ISD1420 chip play back the desired voice pattern we want. Originally, we thought we can just output the appropriate address bit and then make the chip play, however, later on, we discovered there is a THOLD in the ISD1420 chip that we need to take care of, otherwise, it will refer to the previous address bits.
The voice playback chip does not have a very fast internal clock, so we have to manually use the delay function in our program after we set the address bits, and then make the chip play. Although using the delay function is somehow undesirable, however, we have implemented our program such that this delay will not cause any error in our software.