外文翻譯--電鍋爐溫度控制系統(tǒng)-資料下載頁
2024-12-04 12:03本頁面
【導讀】進入的電腦時代。不過，這種電腦，通常是指個人計算機，簡稱PC機，它由主。機、鍵盤、顯示器等組成。機就是把智能賦予各種機械的單片機。的最小系統(tǒng)只用了一片集成電路，即可進行簡單運算和控制。常都藏在被控機械的“肚子”里。它在整個裝置中，起著有如人類頭腦的作用，它出了毛病，整個裝置就癱瘓了。備、導航系統(tǒng)、家用電器等。各種產(chǎn)品一旦用上了單片機，就能起到使產(chǎn)品升級。換代的功效，常在產(chǎn)品名稱前冠以形容詞——“智能型”，如智能型洗衣機等。究其原因，可能就卡在產(chǎn)品未使用單片機。CPU根據(jù)外部事態(tài)的輕重緩急來采取適當?shù)膽洞胧?。用型微處理器相比，它更強調(diào)自供應和節(jié)約成本。范圍更廣的微控制器，但是目前在中國大陸仍多沿用“單片機”的稱呼。說單片機與通用型中央處理單元芯片不同是因為前者。單片機系統(tǒng)植入裝置內(nèi)部來控制裝置了。近年來為了在指令和數(shù)據(jù)上使用不同的。使傳入的數(shù)據(jù)轉化為處理器可以識別的形式。
【正文】 required based on the source of the interrupt before returning to the original instruction sequence. Possible interrupt sources are device dependent, and often include events such as an internal timer overflow, pleting an analog to digital conversion, a logic level change on an input such as from a button being pressed, and data received on a munication link. Where power consumption is important as in battery operated devices, interrupts may also wake a microcontroller from a low power sleep state where the processor is halted until required to do something by a peripheral event. Microcontroller programs must fit in the available onchip program memory, since it would be costly to provide a system with external, expandable, memory. Compilers and assembly language are used to turn highlevel language programs into a pact machine code for storage in the microcontroller39。s memory. Depending on the device, the program memory may be permanent, readonly memory that can only be programmed at the factory, or program memory may be fieldalterable flash or erasable readonly memory. Since embedded processors are usually used to control devices, they sometimes need to accept input from the device they are controlling. This is the purpose of the analog to digital converter. Since processors are built to interpret and process digital data, . 1s and 0s, they won39。t be able to do anything with the analog signals that may be being sent to it by a device. So the analog to digital converter is used to convert the ining data into a form that the processor can recognize. There is also a digital to analog converter that allows the processor to send data to the device it is controlling. In addition to the converters, many embedded microprocessors include a variety of timers as well. One of the most mon types of timers is the Programmable Interval Timer, or PIT for short. A PIT just counts down from some value to zero. Once it reaches zero, it sends an interrupt to the processor indicating that it has finished counting. This is useful for devices such as thermostats, which periodically test the temperature around them to see if they need to turn the air conditioner on, the heater on, etc. Time Processing Unit or TPU for short. Is essentially just another timer, but more sophisticated. In addition to counting down, the TPU can detect input events, generate output events, and other useful operations. Dedicated Pulse Width Modulation (PWM) block makes it possible for the CPU to control power converters, resistive loads, motors, etc., without using lots of CPU resources in tight timer loops. Universal Asynchronous Receiver/Transmitter (UART) block makes it possible to receive and transmit data over a serial line with very little load on the CPU. For those wanting ether one can use an external chip like Crystal Semiconductor CS8900A, Realtek RTL8019, or Microchip ENC 28J60. All of them allow easy interfacing with low pin count
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