1 #include <reg52.h>
  2
  3 typedef unsigned char uint8;
  4
  5 sbit wave=P1^2;    //波形输出
  6 sbit du=P1^0;    //段选锁存器
  7 sbit we=P1^1;    //位选锁存器
  8
  9 #define FNUM 5    //频率数目
 10 #define DNUM 3    //占空比数目
 11
 12 //共阴段码表
 13 uint8 code table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x77,0x7c,0x39,0x5e,0x79,0x71};
 14
 15 unsigned dnum,fnum;
 16 unsigned count;
 17
 18 uint8 key_scan(void);
 19 void display(uint8 num[]);
 20 void delayms(unsigned ms);
 21
 22 void main(void)
 23 {
 24     uint8 fsel=4,dsel=2;    //默认选择
 25     unsigned long freq[FNUM]={1,10,100,1000,5000};    //频率
 26     uint8 duty[DNUM]={25,50,75};    //占空比
 27     uint8 num[4]={0};
 28
 29
 30     TMOD=0x02;    //方式2
 31     TH0=TL0=256-46;    //50us
 32     count=0;
 33     fnum=1000000/50/freq[fsel-1];
 34     dnum=1000000/50/freq[fsel-1]*duty[dsel-1]/100;
 35
 36     EA=1;
 37     ET0=1;
 38     TR0=1;
 39
 40     while(1)
 41     {
 42         switch(key_scan())
 43         {    //分别是频率减、加，占空比减、加，确定键
 44             case 0:
 45                 if(fsel--==1)
 46                     fsel=FNUM;
 47             break;
 48             case 1:
 49                 if(fsel++==FNUM)
 50                     fsel=1;
 51             break;
 52             case 2:
 53                 if(dsel--==1)
 54                     dsel=DNUM;
 55             break;
 56             case 3:
 57                 if(dsel++==DNUM)
 58                     dsel=1;
 59             break;
 60             case 7:
 61             TR0=0;
 62             count=0;
 63             fnum=1000000/50/freq[fsel-1];
 64             dnum=1000000/50/freq[fsel-1]*duty[dsel-1]/100;
 65             TR0=1;
 66
 67             break;
 68             default:    //无键按下
 69             break;
 70         }
 71
 72         //数码管显示选择的频率、占空比
 73         num[1]=fsel;
 74         num[0]=dsel;
 75         display(num);
 76     }
 77 }
 78
 79
 80 //翻转法扫描矩阵键盘，返回按键值
 81 uint8 key_scan(void)
 82 {
 83     uint8 key,i,ret=0xff;    //无键按下返回0xff
 84     P2=0xf0;
 85
 86     if(P2!=0xf0)
 87     {
 88         delayms(10);
 89         if(P2!=0xf0)
 90         {
 91             key=P2;
 92             P2=0x0f;
 93             key|=P2;
 94             while(P2!=0x0f)
 95                 ;
 96             for(i=0;(key>>i)&0x01;i++)
 97                 ;
 98             ret=3-i;
 99             for(i=4;(key>>i)&0x01;i++)
100                 ;
101             ret+=(7-i)*4;
102         }
103     }
104     return ret;
105 }
106
107 //数码管动态显示
108 void display(uint8 num[])
109 {
110     uint8 i;
111     for(i=0;i<4;i++)
112     {
113         P0=0xff;    //消影
114         we=1;
115         we=0;
116
117         P0=table[num[i]];
118         du=1;
119         du=0;
120         P0=~(1<<i);
121         we=1;
122         we=0;
123         delayms(1);
124     }
125 }
126
127 void timer0(void) interrupt 1
128 {
129     count++;
130
131     if(count==fnum)//频率计数值
132     {
133         count=0;
134         wave=1;
135     }
136     else if(count==dnum)//占空比计数值
137         wave=0;
138
139 }
140
141 void delayms(unsigned ms)
142 {
143     uint8 i=11;    //将延时调小
144     while(ms--)
145         while(i--)
146         ;
147 }