【正文】 為了簡化電路，調試方便，是一個 5V 的蜂鳴器自動報警電路中的應用 [8]。 G. 驅動電路 一個步進電機作為驅動裝置來控制溫度。二：當溫度在兩者之間的某處結束，等于設定值時，電機停止。最后，它被放大功 放 2803A 權力電機。但對溫度的檢測，可與 TIMER0計時 1秒，即出現溫度檢測達到每秒。例如，當系 統(tǒng)通電時間碼將在內部單位地址或閃爍標志存儲的信息將被清除。例如，當系統(tǒng)通電后， LCD 應該被初始化，啟動顯示器應該叫，溫度轉換命令時，必須先發(fā)出的時鐘芯片 DS1302也要被初始化。 V. 結論 溫 度控制系統(tǒng)具有友好的人機交互界面，硬件簡單，成本低，溫度控制精度高（誤差在177。 DS18B20。s life to improve the quality of the work and life. It is also versatile, so that it can be convenient to extend the use of the system. So the design is of profound importance. The general design, hardware design and software design of the system are covered. II. SYSTEM GENERAL DESIGN The hardware block diagram of the TC is shown in Fig. 1. The system hardware includes the microcontroller, temperature detection circuit, keyboard control circuit, clock circuit, Display, alarm, drive circuit and external RAM. Based on the AT89S51, the DS18B20 will transfer the temperature signal detected to digital signal. And the signal is sent to the microcontroller for processing. At last the temperature value is showed on the LCD 12232F. These steps are used to achieve the temperature detection. Using the keyboard interface chip HD7279 to set the temperature value, using the microcontroller to keep a certain temperature, and using the LCD to show the preset value for controlling the temperature. In addition, the clock chip DS1302 is used to show time and the external RAM 6264 is used to save the monitoring data. An alarm will be given by buzzer in time if the temperature exceeds the upper and lower limit value of the temperature. III. HARDWARE DESIGN A. Microcontroller The AT89S51 is a lowpower, highperformance CMOS 8bit microcontroller with 4K 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 AT89S51 is a powerful microcontroller which provides a highlyflexible and costeffective solution to many embedded control applications. Minimum system of the microcontroller is shown in Fig. 2. In order to save monitoring data, the 6264 is used as an external RAM. It is a static RAM chip, lowpower with 8K bytes memory. B. Temperature Detection Circuit The temperature sensor is the key part in the system. The Dallas DS18B20 is used, which supports the 1Wire bus interface, and the ONBOARD Patented is used internally. All the sensor parts and the converting circuit are integrated in integrated circuit like a transistor [1]. Its measure range is 55℃ ~125 ℃ , and the precision between 10℃ ~85 ℃ is 177。 besides not equals the preset value. Two: when the temperature is at somewhere between the two ends and equals the preset value, the motor stops. These steps are used to achieve the temperature control. In addition, the motor speed can also be adjusted by relative buttons. As shown in Fig. 8, the code data is input through ports A11~A8 (be ~) of the AT89S51 and inverted output by the inverter 74LS04. Finally it is amplified by the power amplifie