基于ADuC847的I／F轉(zhuǎn)換器的設(shè)計(jì)

　　摘要：I/F轉(zhuǎn)換器即電流頻率轉(zhuǎn)換器，是一種將輸入電流信號(hào)按固定的線性比例關(guān)系轉(zhuǎn)換為輸出頻率信號(hào)的設(shè)備或器件。本文鑒于模擬I/F轉(zhuǎn)換器的轉(zhuǎn)換精度有所限制，設(shè)計(jì)基于ADuC847的I/F轉(zhuǎn)換器。該設(shè)計(jì)是將輸入的雙極性電流信號(hào)調(diào)理成單極性的模擬電壓信號(hào)，并經(jīng)ADuC847的片內(nèi)集成24位Σ-Δ模數(shù)轉(zhuǎn)換器轉(zhuǎn)化為單極性的數(shù)字信號(hào)。濾波歸零后的雙極性數(shù)字信號(hào)通過(guò)計(jì)算線性比例系數(shù)得出輸出頻率值，頻率信號(hào)由ADuC847單片機(jī)的PWM0輸出。

　　關(guān)鍵字：ADuC847;I/F轉(zhuǎn)換器;數(shù)字滑動(dòng)濾波算法;頻率合成算法

　　The design of the current-frequency converter based on the ADuC847

　　Yu Lei, Wang Yanping

　　(Qingdao University of Science and Technology College of Automation and Electronic Engineering, Qingdao 266042)

　　Abstract:I/F converter - the current frequency converter, is the equipment or device of putting an input current signal to convert the output frequency signal with a fixed linear proportional relationship. In view of the limit of the analog I/F converter in conversion accuracy, we design the I/F converter based on the ADuC847.First,we convert the bipolar current input signal into a unipolar analog voltage signal ,and ADuC847 chip with integrates 24 sigma-delta analog-to-digital converts the voltage signal into a unipolar digital signal. After digital signal filtering and zeroing, we get the bipolar output frequency value by calculating the coefficient of linear proportion, and the frequency signal output from the PWM0 of the ADuC847 microcontroller.

　　Key words:ADuC847; current-frequency converter; Digital slide filtering algorithm; Frequency synthesis algorithm

　　I/F轉(zhuǎn)換器即電流頻率轉(zhuǎn)換器是一種將輸入電流信號(hào)按線性的比例關(guān)系轉(zhuǎn)換為輸出頻率信號(hào)的器件，它廣泛應(yīng)用在航空航天，遙感遙測(cè)，遠(yuǎn)距離數(shù)據(jù)采集通信[1]，工業(yè)領(lǐng)域以及軍事領(lǐng)域等方面，尤其是軍事領(lǐng)域?qū)/F轉(zhuǎn)換器的轉(zhuǎn)換精度有較高的要求。以往的I/F轉(zhuǎn)換器以模擬電路為主，由于模擬電路各種噪聲溫漂的影響，在轉(zhuǎn)換精度提高方面有所限制，即使采用補(bǔ)償方式[2]，轉(zhuǎn)換精度也才十萬(wàn)分之六七。隨著數(shù)字電路技術(shù)的發(fā)展，國(guó)外已經(jīng)有了專(zhuān)用的集成電流頻率轉(zhuǎn)換芯片。本文針對(duì)模擬I/F轉(zhuǎn)換器在轉(zhuǎn)換精度方面的不足，設(shè)計(jì)基于ADuC847單片機(jī)的I/F轉(zhuǎn)換器，該I/F轉(zhuǎn)換器大部分采用集成器件，通過(guò)軟件實(shí)現(xiàn)I/F轉(zhuǎn)換的功能。