大神们看看这个程序哪里有问题

1. #include<AT89X51.H>
   
2. #define uchar unsigned char
   
3. #define uint unsigned int
   
4. uchar bbit[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,};
   
5. uchar buffer[]={0,0,0,0};
   
6. uchar minute=0,sec=30;
   
7. uint count;
   
8. uint k;
   
9. 
   
10. sbit FM = P1^7;
    
11. 
    
12. void delay(uchar ms)
    
13. {
    
14. uchar i,j;
    
15. for(i=ms;ms>0;ms--);
    
16. for(j=112;j>0;j--);
    
17. }
    
18. 
    
19. void tt0()interrupt 1 using 1
    
20. {
    
21. TH0=(65535-50000)/256;
    
22. TL0=(65535-50000)%256;
    
23. 
    
24. if(count==10)
    
25. {
    
26. count=0;
    
27. if(sec==0&&minute==0)
    
28. {
    
29. P0=0xc0;
    
30. P2=0x0f;
    
31. P3_0=0;          //rel
    
32. FM=0;
    
33. 
    
34. while(1){P3_1=1;}    //daim yenix
    
35. }
    
36. 
    
37. if(sec==0)
    
38. {
    
39. sec=60;minute--;
    
40. if(minute=9)minute=9;
    
41. }
    
42. sec--;
    
43. if(sec>=59)sec=59;
    
44. }
    
45. 
    
46. buffer[0]=sec%10;
    
47. buffer[1]=sec/10;
    
48. buffer[2]=minute%10;
    
49. buffer[3]=minute/10;
    
50. count++;
    
51. /*if(count%10==0)
    
52. P3_1=0;*/
    
53. }
    
54. 
    
55. void display()
    
56. {
    
57. uchar i;
    
58. for(i=10;i！=0xff;i--)
    
59. {
    
60. P0=buffer[i];
    
61. P2=bbit[i];
    
62. delay(10);
    
63. P0=0xff;
    
64. }
    
65. }
    
66. 
    
67. void main()
    
68. {
    
69. P0=0x00;
    
70. P2=0x0f;
    
71. P3_0=0;
    
72. TMOD=0x01;
    
73. TH0=(65535-50000)/256;
    
74. TL0=(65535-50000)%256;
    
75. EA=0;
    
76. ET0=0;
    
77. while(1)
    
78. {
    
79. buffer[0]=sec%10;
    
80. buffer[1]=sec/10;
    
81. buffer[2]=minute%10;
    
82. buffer[3]=minute/10;
    
83. display();
    
84.        
    
85. if(P1_0==0)
    
86. {
    
87. delay(20);
    
88. if(P1_0==0)
    
89. {sec++;if(sec>=60)sec=0;}while(P1_0==0);
    
90. }
    
91. if(P1_1==0)
    
92. {
    
93. delay(20);
    
94. if(P1_1==0)
    
95. 
    
96. {sec--;if(sec>=60)sec=59;}while(P1_1==0);
    
97. }
    
98. if(P1_3==0)
    
99. {
    
100. delay(20);
     
101. if(P1_3==0)
     
102. {minute++;if(minute>=9)minute=0;}while(P1_3==0);
     
103. }
     
104. if(P1_2==0)
     
105. {
     
106. delay(20);
     
107. if(P1_2==0)
     
108. {minute--;if(minute>=9)minute=9;}while(P1_2==0);
     
109. }
     
110. 
     
111. if(P1_4==0)                     //qikip,wakit balgulaxka baxlax
     
112. delay(20);
     
113. if(P1_4==0)
     
114. {
     
115. EA=1;
     
116. ET0=1;
     
117. TR0=1;
     
118. P3_1=0;
     
119.         while(1)
     
120. {
     
121. display();
     
122. }
     
123. }
     
124. }
     
125. }

什么的图，数码的显示都有问题

共阳的数码管。图上其他多余的线路可以先不看的   现在的主要问题是显示不了倒计时

定时器没开吧?