【正文】 基于AT89C51單片機(jī)的最小系統(tǒng)設(shè)計(jì) 組員： 摘要：本次實(shí)驗(yàn)課題為設(shè)計(jì)一個(gè)基于AT89C51單片機(jī)的最小系統(tǒng)。用P1口設(shè)計(jì)流水燈，用P2口和P0口分別作段選和位選設(shè)計(jì)了六位數(shù)碼管的靜動(dòng)態(tài)顯示和簡(jiǎn)易的電子鐘，用P3口設(shè)計(jì)了一個(gè)4*4的矩陣鍵盤，并用蜂鳴器實(shí)現(xiàn)了唱歌功能和鍵盤按下的聲響，用62256擴(kuò)展內(nèi)部RAM，還擴(kuò)展并實(shí)現(xiàn)了LCD1602的靜動(dòng)態(tài)顯示，最后通過ADC0809和 DAC0832分別實(shí)現(xiàn)了A/D、D/A轉(zhuǎn)換功能。 一、系統(tǒng)電源用MC7805集成穩(wěn)壓器將輸入電壓轉(zhuǎn)為+5V穩(wěn)壓給系統(tǒng)供電。二、晶振（12MHZ）及復(fù)位電路采用12MHz的外部晶振，給系統(tǒng)提供時(shí)鐘信號(hào)。并采用了按鍵復(fù)位電路。三、流水燈功能描述：讓8個(gè)led燈循環(huán)閃爍源程序：流水燈ORG 0000H LJMP MAIN ORG 0100H MAIN:MOV A,11111110B LOOP:MOV P1,A。給P1口送值LCALL DLY RL A 。循環(huán)左移 LJMP LOOP DLY:MOV R7,250 。延時(shí)子程序 DLY1: MOV R6,200 DJNZ R6,$ DJNZ R7,DLY1 RET END四、 數(shù)碼管功能描述：數(shù)碼管動(dòng)態(tài)顯示1~6源程序：ORG 0000HLJMP STARTORG 0100HSTART: MOV P0,0 MOV P2,0F9H SETB LCALL DELAY CLR MOV P2,0C4H SETB LCALL DELAY CLR MOV P2,0D0H SETB LCALL DELAY CLR MOV P2,99H SETB LCALL DELAY CLR MOV P2,92H SETB LCALL DELAY CLR MOV P2,82H SETB LCALL DELAY CLR LJMP START DELAY: MOV R5,10 D1: MOV R6,20 D2: MOV R7,248 DJNZ R7,$ DJNZ R6,D2 DJNZ R5,D1 RETEND五、 4*4矩陣鍵盤和蜂鳴器功能描述：通過按鍵讓數(shù)碼管顯示0F，按鍵按下時(shí)，蜂鳴器響一下。源程序：ORG 0000HLJMP MAINORG 0100HMAIN: MOV P0,0FFHMOV B,4 MOV P3,0F0H。列置0，看行電平 JNB ,L1 JNB ,L2 JNB ,L3 JNB ,L4 AJMP MAINL1: MOV R1,0AJMP LL1L2: MOV R1,1AJMP LL1L3: MOV R1,2AJMP LL1L4: MOV R1,3AJMP LL1LL1: ACALL DL10MS。消抖 MOV A,P3 XRL A,0F0H JZ MAIN MOV P3,0FH。行置0，看列電平 JNB ,L5 JNB ,L6 JNB ,L7 JNB ,L8L5: MOV 20H,0AJMP KEYL6: MOV 20H,1AJMP KEYL7: MOV 20H,2AJMP KEYL8: MOV 20H,3AJMP KEYKEY:MOV A,R1。計(jì)算鍵值并查表賦值 MUL AB ADD A,20H MOV R2,AMOV DPTR,TABLEMOV A,R2MOVC A,@A+DPTRMOV P2,ACALL BEEP_BLLCALL DELAYLJMP MAINBEEP_BL: CLR 。蜂鳴器子程序 ACALL DELAY SETB RETDELAY: MOV R5,50。延時(shí) D1: MOV R6,20 D2: MOV R7,50 DJNZ R7,$ DJNZ R6,D2 DJNZ R5,D1 RETDL10MS:MOV R7,05HLOOP1: MOV R6,0F9HLOOP2:NOP NOP DJNZ R6,LOOP2 DJNZ R7,LOOP1 RETTABLE:DB 0A0H,0F9H,0C4H,0D0H,99H DB 92H,82H,0F8H,80H,90H DB 88H,83H,0A6H,0C1H,86H DB 8EHEND六、 時(shí)鐘功能描述：在數(shù)碼管上實(shí)現(xiàn)時(shí)鐘功能，并通過矩陣鍵盤的3個(gè)鍵實(shí)現(xiàn)復(fù)位，調(diào)時(shí)，調(diào)分。源程序：ORG 0000H LJMP 1000H ORG 001BH AJMP 0100H ORG 0100H MOV TH1,0D8H MOV TL1,0F0H DJNZ 69H,TT1 MOV 69H,100 SETB 4FH TT1:RETI。中斷延時(shí)ORG 1000H MOV 30H,1 MOV 31H,2 MOV 32H,0 MOV 33H,0 MOV 34H,0 MOV 35H,0 MOV TMOD,10H MOV TH1,0D8H MOV TL1,0F0H MOV IE,88HXS0: SETB TR1 MOV 69H,100 CLR 4FHXS00:LJMP KEYKEY。判斷按鍵有無按下LX1: CJNE A,0A0H,LX2LJMP P100LX2: CJNE A,0F9H,LX3LJMP P1000LX3: CJNE A,0C4H,XSLJMP P10000XS: MOV 40H,01H MOV DPTR,TAB MOV P0,40H MOV A,30H MOVC A,@A+DPTR MOV P2,A LCALL YS1MS MOV P2,0FFH MOV A,42H MOV 40H,A MOV P0,40H MOV A,31H ADD A,10 MOVC A,@A+DPTR MOV P2,A LCALL YS1MS MOV P2,0FFH MOV A,44H MOV 40H,A MOV P0,40H MOV A,32H MOVC A,@A+DPTR MOV P2,A LCALL YS1MS MOV P2,0FFH MOV A,48H MOV 40H,A MOV P0,40H MOV A,33H ADD A,10 MOVC A,@A+DPTR MOV P2,A LCALL YS1MS MOV P2,0FFH MOV A,50H MOV 40H,A MOV P0,40H MOV A,34H MOVC A,@A+DPTR MOV P2,A LCALL YS1MS MOV P2,0FFH MOV A,60H MOV 40H,A MOV P0,40H MOV A,35H MOVC A,@A+DPTR MOV P2,A LCALL YS1MS MOV P2,0FFH MOV A, 40H MOV 40H,A JNB 4FH,LLLL1 CLR 4FHLJMP JIA LLLL1:LJMP XS00P100: MOV 30H,0 MOV 31H,0 MOV 32H,0 MOV 33H,0 MOV 34H,0 MOV 35H,0JIA: MOV R1,14H MOV A,35H CJNE A,9,JIA1 MOV 35H,0 MOV A,34H CJNE A,5,JIA10 MOV 34H,0P10000: MOV A,33H CJNE A,9,JIA100 MOV 33H,0 MOV A,32H CJNE A,5,JIA1000 MOV 32H,0P1000: MOV A,31H CJNE A,9,JIA10000 MOV 31H,0MOV A,30H CJNE A,2,JIA100000 MOV 30H,0 AJMP XSJIA100000: INC 30H AJMP XS0JIA10000: CJNE A,3,JIAJIA MOV A,30H CJNE A,02,JIAJIA MOV 30H,0 MOV 31H,0 AJMP XS0JIAJIA: INC 31H AJMP XS0JIA1000:INC 32H AJMP XS0JIA100: INC 33H AJMP XS0JIA10: INC 34H AJMP XS0JIA1: INC 35H AJMP XS0 RET YS1MS: MOV R6,9HYL1: MOV R7,19H DJNZ R7,$ DJNZ R6,YL1 RETDL10MS:MOV R7,05HLOOP1: MOV R6,0F9HLOOP2:NOP NOP DJNZ R6,LOOP2 DJNZ R7,LOOP1 RETDELAY: MOV R5,50 D1: MOV R6,20 D2: MOV R7,248 DJNZ R7,$ DJNZ R6,D2 DJNZ R5,D1 RET 。矩陣鍵盤KEYKEY: MOV B,4 MOV P3,0F0H。列置0，看行電平 JNB ,L1 JNB ,L2 JNB ,L3 JNB ,L4 AJMP XSL1: MOV R1,0AJMP LL1L2: MOV R1,1AJMP LL1L3: MOV R1,2AJMP LL1L4: MOV R1,3AJMP LL1LL1: ACALL DL10MS。消抖 MOV A,P3 XRL A,0F0H JZ LLL2 MOV P3,0FH。行置0，看列電平 JNB ,L5 JNB ,L6 JNB ,L7 JNB ,L8L5:JNB ,L5MOV 20H,0AJMP KEYL6: JNB ,L6MOV 20H,1AJMP KEYL7:JNB ,L7MOV 20H,2AJMP KEYL8: JNB ,L8MOV 20H,3AJMP KEYLLL2:LJMP XSKE