【導(dǎo)讀】顯示位數(shù)：6位，最大顯示數(shù)999999。位時(shí)間內(nèi)對(duì)待測(cè)信號(hào)的脈沖邊沿進(jìn)行計(jì)數(shù)，主要完成測(cè)量過程的控制、測(cè)量結(jié)果的處理和顯示。后，單片機(jī)對(duì)計(jì)數(shù)值進(jìn)行運(yùn)算處理，并送往8位鎖存器74LS273。端口電平相對(duì)應(yīng)的數(shù)字。如圖1-1所示，待測(cè)頻率信號(hào)經(jīng)放大、但是，對(duì)于工作在12MHz晶振下。分頻的常用方法是利用計(jì)數(shù)器，本方案中用了兩。片十進(jìn)制計(jì)數(shù)器74LS90進(jìn)行10分頻和100分頻。數(shù)據(jù)經(jīng)AT89C52的輸出口送到LCD顯示器或數(shù)碼顯示管顯示，對(duì)于LCD顯示器而言，則需要靠編程實(shí)現(xiàn)。示數(shù)據(jù)，測(cè)量范圍為1Hz-10MHz，共分為三檔。計(jì)數(shù)器T0、T1計(jì)數(shù)運(yùn)行控制位TR0、TR1為高仍不能計(jì)數(shù)，整形部分僅由一個(gè)與門構(gòu)成，與門。門的閾值電壓時(shí)，在與門的輸出端將會(huì)得到高電平。成的，AT89C52把記錄的數(shù)據(jù)分解為最高位、次高位……頻率測(cè)量部分：AT89C52單片機(jī)上電后，工作于等待狀態(tài)，計(jì)數(shù)停止，AT89C52對(duì)所計(jì)得的數(shù)進(jìn)行加工并送往鎖存器鎖存，方式，將各個(gè)功能分成獨(dú)立模塊，由系統(tǒng)的程序統(tǒng)一管理執(zhí)行。示為頻率測(cè)量主程序的粗略流程圖。

　　

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