My programis:


ORG 0000H;
SJMP START;
ORG 000BH;
SJMP TIME0;


TIME0: CLR EA;
CLR TR0;
MOV A,#0B1H;
ADD A,TH0;
MOV TH0,A;
MOV A,#0DFH;
ADD A,#0EH;
ADD A,TL0;
JNB ACC.7,TTT;
INC TH0;
TTT:MOV TL0,A;
CPL P1.0;
SETB TR0;
SETB EA;
RETI;




START:MOV R7,#0FFH;
START1:MOV R6,#0FFH;
START2:NOP;
NOP;
DJNZ R6,START2;
DJNZ R7,START1;
MOV SP,#060H;
MOV TMOD,#01H;
MOV P1,#0FFH;
MOV TL0,#0DFH;
MOV TH0,#0B1H;
SETB TR0;
SETB EA;
SETB P1.0;
LOOP:MOV R7,#0FFH;
MUL AB;
MUL AB;
DJNZ R7,LOOP;
SJMP LOOP;
NOP;
NOP;
END;
Here,fosc=12MHZ,mcu is at89c51,I want to generate a pulse wave of 50HZ.But I can't get the square wave ,what's the matter,hope anyone knows gives me some advice>Thanks.

Qiqiao Hu