8251序列介面應用實驗：輸出部分方波
阿新 • • 發佈：2019-01-08
實驗現象：
在示波器上觀察到類似方波的波形（形如101010100）
實驗程式碼：
1 Con_8253 EQU 0B003H 2 T2_8253 EQU 0B002H 3 CTL_ADDR EQU 0F001H 4 DATA_ADDR EQU 0F000H 5 _STACK SEGMENT STACK 6 DW 100 DUP(?) 7 _STACK ENDS 8 CODE SEGMENT 9 ASSUME CS:CODE 10 START: CALL INIT_8253 11 CALL INIT_8251 12 A1: CALL SEND 13 MOV CX,0FFFH 14 A2: MOV AX,01E0H 15 A3: DEC AX 16 JNZ A3 17 LOOP A2 18 JMP A1 19 INIT_8253 PROC NEAR 20 MOV DX,Con_8253 21 MOV AL,96H 22 OUT DX,AL 23 MOV DX,T2_8253 24 MOV AL,26H 25 OUT DX,AL 26 RET 27 INIT_8253 ENDP 28 INIT_8251 PROC NEAR 29 CALL Reset_8251 30 MOV DX,CTL_ADDR 31 MOV AL,7EH 32 OUT DX,AL 33 CALL DLTIME 34 MOV AL,31H 35 OUT DX,AL 36 CALL DLTIME 37 RET 38 INIT_8251 ENDP 39 Reset_8251 PROC NEAR 40 MOV DX, CTL_ADDR 41 MOV AL,0 42 OUT DX,AL 43 CALL DLTIME 44 OUT DX,AL 45 CALL DLTIME 46 OUT DX,AL 47 CALL DLTIME 48 MOV AL,40H 49 OUT DX,AL 50 CALL DLTIME 51 RET 52 Reset_8251 ENDP 53 DLTIME PROC NEAR 54 MOV CX,10 55 LOOP $ 56 RET 57 DLTIME ENDP 58 SEND: MOV AL,55H 59 MOV DX,DATA_ADDR 60 OUT DX,AL 61 RET 62 CODE ENDS 63 END START