1.原理图：

2.程序例子(汇编例子)：
;*****************************************************************************
;*实验名称：定时器0中断和外中断1实验(T0中断和INT1同时存在)
;*实验对象：XY-900_USB型单片机学习开发系统    http://www.mcusy.cn  
;*实验说明：开机P2 每隔0.5S做左移一位，按P3.3(INT1中断)，LED闪烁5次后返回
;*****************************************************************************
; 提示：如果有多个中断，中断向量在程序起始处一定要按中断顺序排列，否则出现问题
             ORG 00H
             AJMP START
             ORG 0BH                   ;T0中断起始地址
             JMP TIM0
             ORG 13H                     ;INT1(P3.3)中断起始地址
             AJMP EXT1
START: MOV SP,#70H
             MOV TMOD,#00000001B
             MOV TH0,#HIGH(65536-10000) ;1000US
             MOV TL0,#LOW(65536-10000)     ;
             SETB TR0                   ;启动T0
             MOV IE,#10000110B ;T0、INT1中断使能,
             MOV IP,#00000100B ;设定INT1优先
             MOV R5,#100             ;中断100次即1S
             MOV R1,#0FEH           ;循环初值
             JMP $
TIM0:   PUSH ACC                   ;将A压入堆栈暂时保护
             PUSH PSW
             MOV TH0,#HIGH(65536-5000) ;500US
             MOV TL0,#LOW(65536-5000)     ;
             DJNZ R3,LOOP           ;中断了100次？
             MOV R3,#100             ;重设R5=100
             MOV A,R1                   ;读入P1至A
             MOV P2,A
             RL A                           ;A的值左移一位
             MOV R1,A                   ;存入左移初值

LOOP:   POP PSW                     ;恢复PSW
             POP ACC
             RETI
EXT1:   PUSH ACC
             PUSH PSW
             MOV A,#00
             MOV R2,#10               ;闪灯5次
LOOP3: MOV P2,A
             CALL DELAY
             CPL A
             DJNZ R2,LOOP3
             POP PSW
             POP ACC
             RETI
;---------- 以下是延时子程序 ----------------------------------
DELAY: MOV R5,#20                   ;0.2S
D1:       MOV R6,#20                   ;10MS
D2:       MOV R7,#248                 ;0.5MS
             DJNZ R7,$
             DJNZ R6,D2
             DJNZ R5,D1
             RET
             END