【正文】 stacle distance is the time which sends out through the sound navigation and ranging reflects spends determines and carries on the putation. The reflection signal causes the D trigger to produce interrupt request signal INT1,simultaneously stops counting, reads takes counts the value, calculates the actual distance after the formula, then carries on the parison with the datum distance, if examines when the actual distance is bigger than reference value 80cm, does not carry on the accustomoptics to report to the police。 Alarm apparatus interrupt handling routine. This alarm apparatus installs on the automobile steering wheel. After installs, starts the alarm apparatus, the alarm apparatus automatically retards20~30s to start to work, in order to lets use the person to have the enough time to lock the gate to leave the automobile. After the time delay the alarm apparatus enters the value to defend the active status, once the vehicle door is turned on or the windowpane hits garrulously, the oscillation pickup examines the signal, time delay 20s starts to report to the police. The time delay goal is the master which causes the automobile is opening the gate to enter the vehicle internal energy closure alarm apparatus, in order to avoid reports to the police by mistake. Master routineThis part mainly pletes to each severance entrance hypothesis, and reports to the police the depositing unit initialization to each fixed unit, establishes the special symbol value and to the pressed key interrupts processing. Master routine design diagram like chart 2 shows.Chart2 master routine frame chart Alarm apparatus interrupt handling routineThe burglar alarm disposal procedure uses time severance inquiry processing, each time severance, only is inquires each kind of control flag bit, controls each group output according to its condition. The procedure has not used has circulation processing the way, therefore time control conclusion, cannot eliminate controls the flag bit, only is repositions the scene, the waiting next time severance, again judges whether controls the conclusion.3. Concluding remarkUses automobile security alarm system cost which this kind of monolithic integrated circuit poses low, performance reliable, simultaneously settles the extension to be convenient. The use jump code code/decoding principle, causes the system to be safer, greatly reduces password explaining rate, will obtain the wide spread application in the future automobile security alarm system.基于單片機的汽車防盜報警系統(tǒng)設(shè)計摘要: 應(yīng)用單片機內(nèi)部資源實現(xiàn)的跳變編碼/解碼汽車防盜系統(tǒng)，它每次使用的遙控密碼都在變化，既提高了系統(tǒng)的安全性，又大大降低了成本。汽車防盜的檢測,采用超聲波傳感器。并觸發(fā)一個高電平，驅(qū)動無線信號發(fā)射電路。編碼序號碼于記錄編碼的次序，其初始值為0 ，單片機每編碼一次，編碼序號碼就向上計數(shù)一次。 防盜報警的實現(xiàn)若有盜車者入室，發(fā)動汽車，輸入錯誤的密碼后，則汽車電瓶的+12V 電壓，點火電流途經(jīng)點火開關(guān)，點火電流中斷，發(fā)動機熄滅，再啟動，將重復(fù)上述過程，這樣，盜賊始終不能將汽車開動，不能達(dá)到其預(yù)期目的。延時后報警器進入值守工作狀態(tài)，一旦車門被打開或窗玻璃被敲碎，振動傳感器檢測到信號，延時 20s開始報警。