【導(dǎo)讀】本系統(tǒng)采用了89C52單片機和四位半AD7135系統(tǒng)設(shè)計技術(shù)，能對。傳感器產(chǎn)生的模擬信號進行數(shù)據(jù)采集和處理。傳感器方面選用了TP-2常溫型CO. 氣敏傳感器，并采用了恒流源接法。器報警裝置，使智能化程度更高、結(jié)構(gòu)更緊湊、功能更豐富。第一章功能與設(shè)計方案----------------------------------------------. 第二章硬件電路設(shè)計--------------------------------------------------. 第三章軟件設(shè)計----------------------------------------------------------. 附錄1相關(guān)英文資料----------------------------------------------------

　　

【正文】 號寄存器 MOV @R0 ,A 。保存鍵值 MOV R4 ,00H 。設(shè)首行初值 MOV DPTR ,KEYTBL 。查表地址首址為 KEYTBL PRSD3: CLR A 。累加器清 0 MOVC A ,@A+DPTR 。查表 MOV 50H ,@R0 。取鍵值 CJNE A ,50H ,NEQ 。是否與按鍵值相等 AJMP E 。等 NEQ : INC R4 。行 +1 INC DPTR 。表地址 +1 AJMP PRSD3 。重新判斷 E : MOV R6 ,0EH 。保存地址 +1 INC R0 。等待存下一鍵值 LJMP DONE 。返回 ,等待按鍵 DLY : ACALL DL10mS 。調(diào)延時 10mS 子程序 DJNZ R6 ,DLY DL10mS: MOV R7 ,10 。設(shè)延時 10mS,置 R7 初值 DL : MOV R5 ,9AH 。置寄存器 R5 初值 西安電子科技大學(xué)畢業(yè)論文 26 DL5 : DJNZ R5 ,DL5 。延時 1mS 循環(huán) DJNZ R7 ,DL 。延時 10mS 循環(huán) RET 。返回 KEYTAB: DB 81H 41H 21H 11H DB 82H 42H 22H 14H DB 84H 44H 24H 14H DB 88H 48H 28H 18H 三 AD7135 數(shù)據(jù)處理： MOV 36H ,A INC R5 MOV A ,R5 MOVC A ,@A+DPTR INC R5 MOV 37H ,A MOV A ,36H CJNE A ,30H ,$+8 MOV A ,37H CJNE A ,31H ,$+3 JNC POSISTOP LCALL DTOF MOV R1 ,33H 。(XA)*10/B+C LCALL FSUB 。A[33H] MOV 39H ,2 。B[36H]_ ANL A ,0FH MOV 3CH ,A NOP RETI 四 LED 顯示控制程序： MOV RO ,08H 。清屏 西安電子科技大學(xué)畢業(yè)論文 27 TP : MOV A ,0FFH MOV SUBF,A DJNZ R2 ,TP MOV R2 ,04H 。設(shè)置顯示個數(shù) MOV A ,0FFH START : INC A MOV R0 ,A MOV SCON,00H 。初始化串行口方式 DISKEY: MOV DPTR,TAB 。查表地址首址為 TAB MOVC A ,@A+DPTR 。差表 LOOP : MOV SBUF,A 。送數(shù) SBUF LP : JNB TI ,LP 。(TI)=1 轉(zhuǎn) LP,否則繼續(xù)執(zhí)行 CLR TI 。清零 MOV A ,R0 DJNZ R2 ,START 。未顯示完 ,繼續(xù)執(zhí)行 RET TAB : DB 0C0H,0F9H,0A4H,0B0H,O99H 。共陽極數(shù)碼管顯示查表 DB 092H,082H,0F8H,080H,090H 西安電子科技大學(xué)畢業(yè)論文 28 結(jié) 束 語 經(jīng)過幾個 月的緊張努力 ,我的畢業(yè)設(shè)計終于順利完成了。在這中間 ,我感覺真的學(xué)到了很多東西 ,并且 ,把以前學(xué)的不好的知識又重新鞏固了一遍 ,而且還加深了理解與認(rèn)識。在畢設(shè)過程中 ,由于要查閱很多資料 ,還使我開闊 了眼界 ,拓展了思路。 實踐出真知 !在畢業(yè)設(shè)計的實踐中 ,我收獲頗豐。我能熟練地運用protel99,office2021 等應(yīng)用軟件 .以前學(xué)習(xí)時總認(rèn)為學(xué)的都用不上 ,而且學(xué)習(xí)的時候抓不到要點 ,通過完成畢業(yè)設(shè)計我初步明白了怎樣把所學(xué)的知識運用到實踐中來 ,終于能夠做到學(xué)以致用。同時由于自己獨立的開發(fā)一套系統(tǒng)，所以我從系統(tǒng)設(shè)計思想、設(shè)計方案、制作電路板等都是自己動手的，使我的動手能力和實踐能力以及社會經(jīng)驗都有所加強。 感謝給予我親切指導(dǎo)的各位老師 ,尤其是我的畢業(yè)設(shè)計老師李智奇老師 ,是她的悉心教導(dǎo)才使我的這篇論文得以完成 !謝謝您 !李老師 !此外 ,還要特別感謝陳大兵同學(xué) ,他在軟硬件及調(diào)試方面都給了我很大的幫助 ,在此表示最誠摯的謝意 ! 西安電子科技大學(xué)畢業(yè)論文 29 附錄 1： Semiconductor Gas Sensors Research and development of gas sensors have shown great advances during the past decade. Semiconductor gas sensors mainly using SnO2 elements have been prevailing as detectors or alarms for leakage of LP ( Liquified Propane) gas and town gas, in addition to other applications. Gas sensors based on MOSFET, first proposed in 1975,have attracted interests of many researchers, and have been developed to a point of mercialization as a hydrogen detector. Solid electrolytes, represented by stabilized zirconia, have proven to be very promising sensor materials for oxygen, SO2, etc. This paper aims at reviewing briefly recent advances and trends in semiconductor gas sensors which were developed in a recent few years. Semiconductor gas sensors detect gases from a change in electrical resistance of an element made with a semiconductive metal oxide, typically SnO2. Although sensors utilizing γ Fe2O3 or α Fe2O3 have been put into practical use, SnO2 sensor still has an overwhelming market share. The production of semiconductor gas sensors has grown into a large industry: more than 5 million pieces were produced in 1983. Most of them have been used in domestic homes as detectors or alarms for gas 西安電子科技大學(xué)畢業(yè)論文 30 leakage. Field statistics has shown that gas alarms are quite effective to prevent an outbreak of gas leakage accident。 the accident rate sharply decreases with an increase in gas alarm installation rate. It is useful to know actual Ltd. has analyzed the cases where gas alarms were effective for prevention of disastorous gas accidents. The result is shown in . The causes are associated dominantly with mishanding or defects of gas appliances (%), and then with stopcocks (%), suicides (%), gas pipes (%), connectors (%), and the others (%). It is rather surprising that suicides are ranked in the third place in this analysis. Anyway semiconductor gas sensors have been so far given much credit as an important device for home security and the installation rate of gas alarms is increasing year after year. Several years ago a problem arose about SnO2 gas sensor when it was adopted at places like kitchens of underground restaurants where various inflammable gases came out into atmosphere from fuels and cookings very frequently during working time. In such a dirty atmosphere, the gas sensor tended to given an alarm at an inflammable gas concentration which was lowered gradually with an elapse of operation time. It has been pointed out that the problem was contributed by various factors but was associated most profoundly with the lowering of electric resistance of the sensor element due to its sintering at unexpectedly high working temperatures. The problem have been almost solved after revisions were made to the sensor element. 西安電子科技大學(xué)畢業(yè)論文 31 Semiconductor gas sensors is being applied in various fields, domestic and industrial. Carbon monoxide has often been used as a sample gas for