【正文】 SJMP KEY_DOWNERETURN2: RETI 。無鍵按下則返回中斷斷點(diǎn)繼續(xù)等待KEY_DOWN0: 。 0鍵按下，R1賦非零值1其它積存器賦0 MOV R1,1 MOV R3,0 MOV R4,0 MOV R0,0 MOV R6,0 MOV R7,0 RETKEY_DOWNF: MOV R3,1 MOV R1,0 MOV R4,0 MOV R0,0 MOV R6,0 MOV R7,0 RETKEY_DOWNE: MOV R4,1 MOV R3,0 MOV R1,0 MOV R0,0 MOV R6,0 MOV R7,0 RETKEY_DOWNX: MOV R4,0 MOV R3,0 MOV R1,0 MOV R0,1 MOV R6,0 MOV R7,0 RETKEY_DOWN1: MOV R4,0 MOV R3,0 MOV R1,0 MOV R0,0 MOV R6,0 MOV R7,1 RETKEY_DOWN2: MOV R4,0 MOV R3,0 MOV R1,0 MOV R0,0 MOV R6,1 MOV R7,0 RETRUN: DJNZ 40H,XIANSHI 。延時顯示 MOV 40H,50 LOOP8: JB ,LOOP8 。外部脈沖高電平等待LOOP9: JNB ,LOOP9 。外部脈沖低電平等待 INC A 。輸入一個脈沖累加器加1 PUSH ACC 。保護(hù)累加器中值不被改變 CLR C 。清進(jìn)位位標(biāo)志寄存器 SUBB A,10 。十個脈沖脈沖計數(shù)數(shù)碼管加1 POP ACC JC LOOP8 。不到10個脈沖則繼續(xù)等待 INC 71H DJNZ 50H,XIANSHI MOV 50H,10 INC 72H 。脈沖計數(shù)低位滿10高位加1 MOV 71H,00H DJNZ 51H,XIANSHI MOV 51H,10LP5: INC 73H 。 外部脈沖達(dá)到1000個里程加1 CLR C MOV A,74H SUBB A,1 。 判斷里程高位是否大于0 JC LP9 。否則轉(zhuǎn)去低位與3比較的程序段 AJMP LP1LP9: CLR C MOV A,73H SUBB A,3 JC LP3 。里程低位小于3則價格不變，從新計外部脈沖 AJMP LOOP1 。里程低位大于3則轉(zhuǎn)到價格加1的程序段LP3: MOV 71H,00H MOV 72H,00H DJNZ 52H,XIANSHI MOV 52H,10 。脈沖計數(shù)數(shù)碼管從新計數(shù) INC 74H MOV 71H,00H MOV 72H,00H MOV 73H,00H DJNZ 53H,XIANSHI MOV 53H,10LOOP1: 。R5內(nèi)容為1則價格加1否則價格加倍 CJNE R5,1,LP1 INC 75HLP1: INC 75H CLR C MOV A,75H SUBB A,0AH JC LP2 。 價格低位滿10則轉(zhuǎn)去高位加1程序段執(zhí)行 AJMP LP4 。顯示價格低位的數(shù)碼管從新計數(shù)LP2: SJMP LP3 LP4: INC 76H MOV 75H,00H AJMP LP3 XIANSHI: 。相應(yīng)內(nèi)存單元為高電平則轉(zhuǎn)去用于該數(shù)碼管顯示的程序段 JB 00H,P10 JB 01H,P100 JB 02H,P1000 JB 03H,P10000 JB 04H,P100000 MOV DPTR,0FF20H 。取8255PA口地址 MOV A,0FEH MOVX @DPTR,A 。初始化PA口 MOV A,71H MOV DPTR,TAB1 。查表獲取十個字型碼 MOVC A,@A+DPTR MOV DPTR,0FF21H 。將獲取的字型碼送數(shù)碼管顯示 MOVX @DPTR,A CPL 00H 。各內(nèi)存單元值取反 CPL 01H CPL 02H CPL 03H CPL 04H LJMP RETURN 。長轉(zhuǎn)移返回中斷P10: 。 脈沖計數(shù)的高位顯示程序 MOV DPTR,0FF20H MOV A,0FDH MOVX @DPTR,A MOV A,72H MOV DPTR,TAB1 MOVC A,@A+DPTR MOV DPTR,0FF21H MOVX @DPTR,A CPL 00H LJMP RETURNP100: 。里程低位的顯示程序段 MOV DPTR,0FF20H MOV A,0FBH MOVX @DPTR,A MOV A,73H MOV DPTR,TAB1 MOVC A,@A+DPTR MOV DPTR,0FF21H MOVX @DPTR,A CPL 01H LJMP RETURNP1000: 。里程高位顯示的程序段 MOV DPTR,0FF20H MOV A,0F7H MOVX @DPTR,A MOV A,74H MOV DPTR,TAB1 MOVC A,@A+DPTR MOV DPTR,0FF21H MOVX @DPTR,A CPL 02H LJMP RETURNP10000: 。價格低位的顯示程序段 MOV DPTR,0FF20H MOV A,0EFH MOVX @DPTR,A MOV A,75H MOV DPTR,TAB1 MOVC A,@A+DPTR MOV DPTR,0FF21H MOVX @DPTR,A CPL 03H LJMP RETURNP100000: 。價格高位的顯示程序段 MOV DPTR,0FF20H MOV A,0DFH MOVX @DPTR,A MOV A,76H MOV DPTR,TAB1 MOVC A,@A+DPTR MOV DPTR,0FF21H MOVX @DPTR,A CPL 04H LJMP RETURNRETURN: RETITAB1: 。字型表 DB 0C0H,0F9H,0A4H,0B0H,99H,92H,82H,0F8H,80H,90H ENDEND35