#include#define uchar unsigned charuchar pwm;sbit pluse=P1^0;void t0isr() interrupt 1{pwm++;if(pwm<4)pluse=1;else pluse=0;pwm%=5;}main(){TMOD=0x02;TH0=256-80;TL0=256-80;TR0=1;ET0=1;EA=1;while(1);}