實(shí)驗(yàn)六-計(jì)數(shù)器改

基礎(chǔ)電子線路實(shí)驗(yàn)（九）計(jì)數(shù)器實(shí)驗(yàn)2024/1/131一、實(shí)驗(yàn)?zāi)康氖煜び?jì)數(shù)器的邏輯功能掌握任意進(jìn)制計(jì)數(shù)器的設(shè)計(jì)方法學(xué)習(xí)數(shù)碼管的使用方法2024/1/132計(jì)數(shù)器二、實(shí)驗(yàn)器材74LS90集成二—五—十進(jìn)制計(jì)數(shù)器1片74LS00二輸入與非門1片2024/1/133計(jì)數(shù)器三、實(shí)驗(yàn)原理1、計(jì)數(shù)器的功能及分類計(jì)數(shù)器是對(duì)輸入的時(shí)鐘脈沖進(jìn)行計(jì)數(shù)的器件，按計(jì)數(shù)進(jìn)制可分為二進(jìn)制和二—十進(jìn)制計(jì)數(shù)器，按輸出端翻轉(zhuǎn)方式可分為同步計(jì)數(shù)器和異步計(jì)數(shù)器，按計(jì)數(shù)趨勢(shì)又可分為加法計(jì)數(shù)器和減法計(jì)數(shù)器。2024/1/134計(jì)數(shù)器2、集成二—五—十進(jìn)制計(jì)數(shù)器74LS90QDQCQBQACP2CP1R0(1)R0(2)S9(1)S9(2)若從CP1輸入，從QA輸出，為二進(jìn)制計(jì)數(shù)器若從CP2輸入，從QDQCQB輸出，為五進(jìn)制計(jì)數(shù)器若CP2與QA相連，從CP1輸入，則為8421碼十進(jìn)制計(jì)數(shù)器若CP1與QD相連，從CP2輸入，則為5421碼十進(jìn)制計(jì)數(shù)器R0(1)

、R0(2)同為1時(shí)，將計(jì)數(shù)器置0（即0000）S9(1)

、S9(2)同為1時(shí)，將計(jì)數(shù)器置9（即1001）2024/1/135計(jì)數(shù)器3、任意進(jìn)制計(jì)數(shù)器設(shè)計(jì)方法（七進(jìn)制）（1）復(fù)位法（置0法）QAQBQCQDCP2CP1R0(1)R0(2)S9(1)S9(2)CP設(shè)第0個(gè)狀態(tài)輸出0000則CP從0計(jì)到6計(jì)數(shù)器都正常工作輸出從0000變化到0110當(dāng)CP計(jì)到7時(shí)，輸出0111應(yīng)使R0(1)=1，R0(2)=1，輸出將被復(fù)位成0000也就是說(shuō)0111這個(gè)狀態(tài)被0000所取代計(jì)數(shù)器只從0計(jì)到6便又回到0，從而實(shí)現(xiàn)七進(jìn)制計(jì)數(shù)R0(1)=QAR0(2)=QBQC2024/1/136計(jì)數(shù)器3、任意進(jìn)制計(jì)數(shù)器設(shè)計(jì)方法（七進(jìn)制）（1）置位法（置9法）設(shè)第0個(gè)狀態(tài)輸出0000則CP從0計(jì)到5計(jì)數(shù)器都正常工作輸出從0000變化到0101當(dāng)CP計(jì)到6時(shí)，輸出0110使S9(1)=1，S9(2)=1，輸出被置成1001也就是說(shuō)0110這個(gè)狀態(tài)被1001所取代計(jì)數(shù)器只從0計(jì)到5后便直接到9，之后再回到0從而也實(shí)現(xiàn)了七進(jìn)制計(jì)數(shù)。S9(1)=QCS9(2)=QBQAQBQCQDCP2CP1R0(1)R0(2)S9(1)S9(2)CP2024/1/137計(jì)數(shù)器四、實(shí)驗(yàn)內(nèi)容測(cè)試集成計(jì)數(shù)器74LS90的邏輯功能用復(fù)位法和置位法設(shè)計(jì)七進(jìn)制計(jì)數(shù)器2024/1/138計(jì)數(shù)器五、注意事項(xiàng)特別注意74LS90的電源(5)和地(10)的位置在計(jì)數(shù)時(shí)，復(fù)位端和置位端要接地

CP輸入要用脈沖，其它用邏輯開(kāi)關(guān)

數(shù)碼管的選擇開(kāi)關(guān)要放到“共陽(yáng)”的