【正文】 這一位置 “1”， ALE 僅在執(zhí)行 MOVX 或 MOVC指令時有效?？撮T狗計時完成后， RST 腳輸出 96個晶振周期的高電平。在使用 8位地址（如 MOVX RI）訪問外部數(shù)據(jù)存儲器時， P2口輸出 P2鎖存器的內(nèi)容。對 P1 端口寫 “1”時，內(nèi)部上拉電阻把端口拉高，此時可以作為輸入口使用。 VCC : 電源 GND: 地 P0 口： P0口是一個 8位漏極開路的雙向 I/O口。在此謹向他們表示衷心地感謝 ! 齊齊哈爾大學畢業(yè)設計（論文） 34 參考文獻 [1]王元慶 .新型傳感器原理及應用 [M].北京：機械工業(yè)出版社， 2021:6769. [2]王幸之等 .AT89 系列單片機原理與接口 [M]．北京：北京航空航天大學， 2021:104106. [3]牛德芳 .半導體傳感器原理及應用 [M].大連：大連理工大學出版社， 1993:97101. [4]厲玉鳴 .化工儀表及自動化 [M].北京：化學工業(yè)出版社， 2021:144147. [5]李永生，楊莉玲 .半導體氣敏元件的選擇性研究 [J].傳感器技術 .2021， (3):13. [6]李 忠國，陳剛 .單片機應用技能實訓 [M].北京：人民郵電出版社， 2021:4952. [7]阮維國 .TGS813型半導體氣敏傳感器及其在燃氣毒氣檢測中的應用電路 [J].現(xiàn)代科學儀器 .1998， (3):12 [8]宋浩，田豐 .單片機原理及應用 [M].北京：清華大學出版社， 2021:133136. [9]張保衛(wèi)，尚家封，趙金水 .燃氣報警器的分類與選擇 [J].山東消防， 2021， (8):12 [10]羅翼，張宏偉 .PIC單片機應用系統(tǒng)開發(fā)典型實例 [M].北京：中國電力出版社，2021:111121. [11]郝魁紅，王化祥，何永勃 .TGS813氣敏元件低溫特性及其非線性分析 [J].電子元件與材料 .2021， 23(3):13. [12]閻石 .數(shù)字電子技術基礎 [M].北京：高等教育出版社， 1998:123129. [13]堂賢遠，劉歧山 .傳感器原理及應用 [M].西安：電子科技大學出版社， . [14]童詩白，華成英 .模擬電子技術基礎 [M].北京：高等教育出版社， 2021:6570. [15]蔡可芬，莊牧林 .燃氣報警器質(zhì)量分析評估 [J].傳感器技術 .1999， 18(4):22. [16]潘 天紅，趙德安，鄒小波 .氣體傳感器陣列中的信息融合 [J].計算機測量與控制 .2021， (10):13. [17] Cai Kefen. New Problems of Gas Sensors[J]. Journal of Transducer Technology，1990， (6)： 13 . [18]STC89C52 Date Sheet. [EB/OL]. /soft/mcu51/， 2021. 齊齊哈爾大學畢業(yè)設計 (論文 ) 35 附錄 A：硬件電路總圖 齊齊哈爾大學畢業(yè)設計（論文） 36 附錄 B：外文文獻及譯文 STC89C52 Date Sheet Description The STC89C52 is a lowpower， highperformance CMOS 8bit microcontroller with 8K bytes of insystem programmable Flash memory. The device is manufactured using Atmel’s highdensity nonvolatile memory technology and is patible with the industrystandard 80C51 instruction set and pinout. The onchip Flash allows the program memory to be reprogrammed insystem or by a conventional nonvolatile memory programmer. By bining a versatile 8bit CPU with insystem programmable Flash on a monolithic chip， the Atmel STC89C52 is a powerful microcontroller which provides a highlyflexible and costeffective solution to many embedded control applications. The STC89C52 provides the following standard features: 8K bytes of Flash， 256 bytes of RAM， 32 I/O lines， Watchdog timer， two data pointers， three 16bit timer/counters， a sixvector twolevel interrupt architecture， a full duplex serial port， onchip oscillator， and clock circuitry. In addition， the STC89C52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM， timer/counters， serial port， and interrupt system to continue functioning. The Powerdown mode saves the RAM contents but freezes the oscillator， disabling all other chip functions until the next interrupt or hardware reset. VCC Supply voltage. GND Ground. Port 0 Port 0 is an 8bit open drain bidirectional I/O port. As an output port， each pin can sink eight TTL inputs. When 1sare written to port 0 pins， the pins can be used as highimpe dance inputs. Port 0 can also be configured to be the multiplexed loworder address/data bus during accesses to external program and data memory. In this mode， P0 has internal pullups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pullups are required during program verification. Port 1 Port 1 is an 8bit bidirectional I/O port with internal pullups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins， they are pulled high by the internal pullups and can be used as inputs. As inputs， Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups. In addition， and can be configured to be the timer/counter 2 external count input () and the timer/counter 2 trigger input ()， respectively， Port 1 also receives the loworder address bytes during Flash programming and verification 齊齊哈爾大學畢業(yè)設計 (論文 ) 37 Port 2 Port 2 is an 8bit bidirectional I/O port with internal pullups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins， they are pulled high by the internal pullups and can be used as inputs. Port 2 emits the highorder address byte during fetches from external program memory and during accesses to external data memory that use 16bit addresses (MOVX DPTR). In this application， Port 2 uses strong internal pullups when emitting 1s. During accesses to external data memory that use 8bit addresses (MOVX RI)， Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the highorder address bits and some control signals during Flash programming and verification. Port 3 Port 3 is an 8bit bidirectional I/O port with internal pullups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins， they are pulled high by the internal pullups and can be used as inputs. As inputs， Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups. Port 3 also serves the functions of various special features of the STC89C52， as shown in the following table. Port 3 also receives some control signals for Flash programming and verification. RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives High for 96 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO， the RESET HIGH out feature is enabled. ALE/PROG Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during acces