[KeilC51]软件简单PWM波生成

应用在某些硬件资源不够用的情况下，不是很精确，频率的话也不是很好调节；

原理就是“J满则溢”。

 

1.中断1服务程序不改变占空比：

 

2.终端1服务程序改变占空比：（明显可以看到波形随时间变化推移）

 

例程代码如下：

 1 #include <reg52.h>
 2 // CPU  STC89C52RC 12T 11.0592M的晶振
 3 #define LED_PORT P0
 4 sbit P0_0 = LED_PORT^0;
 5 sbit P0_1 = LED_PORT^1;
 6 sbit P0_2 = LED_PORT^2;
 7 sbit P0_3 = LED_PORT^3;
 8 sbit P0_4 = LED_PORT^4;
 9 sbit P0_5 = LED_PORT^5;
10 sbit P0_6 = LED_PORT^6;
11 sbit P0_7 = LED_PORT^7;
12 
13 unsigned char sum_temp0,sum_temp1,sum_temp2,sum_temp3,sum_temp4,sum_temp5,sum_temp6,sum_temp7;
14 unsigned char incre_step0,incre_step1,incre_step2,incre_step3,incre_step4,incre_step5,incre_step6,incre_step7;
15 void main(void){
16     TMOD = 0x21; 
17     TCON = 0x00;
18 
19     TR1=0;
20     TH1=(65536-50000)/256; 
21     TL1=(65536-50000)%256; 
22     TF1=0; 
23     TR1=1;
24     ET1=1;
25     EA = 1;
26  sum_temp0 = sum_temp1 = sum_temp2 = sum_temp3 = sum_temp4 = sum_temp5 = sum_temp6 = sum_temp7 = 0;
27  incre_step0 = 0x10;
28  incre_step1 = 0x30;
29  incre_step2 = 0x50;
30  incre_step3 = 0x70;
31  incre_step4 = 0x90;
32  incre_step5 = 0xb0;
33  incre_step6 = 0xd0;
34  incre_step7 = 0xf0;
35     while(1){
36         sum_temp0 += incre_step0;
37         P0_0 = CY;
38         sum_temp1 += incre_step1;
39         P0_1 = CY;
40         sum_temp2 += incre_step2;
41         P0_2 = CY;
42         sum_temp3 += incre_step3;
43         P0_3 = CY;
44         sum_temp4 += incre_step4;
45         P0_4 = CY;
46         sum_temp5 += incre_step5;
47         P0_5 = CY;
48         sum_temp6 += incre_step6;
49         P0_6 = CY;
50         sum_temp7 += incre_step7;
51         P0_7 = CY;
52         }
53 }
54 
55 
56 
57 void Timer1_ISR(void) interrupt 3
58 {
59     static unsigned short int count = 0;
60     unsigned char temp;
61     TR1=0;
62     TH1=(65536-50000)/256; 
63     TL1=(65536-50000)%256; 
64     TF1=0; 
65     TR1=1;
66     
67     count++;
68     
69 #ifdef __NOTCHANGE__
70     return ;
71 #endif  //如果不管变就直接返回
72     
73     if(count == 500){
74         temp = incre_step0;
75         incre_step0 = incre_step1;
76         incre_step1 = incre_step2;
77         incre_step2 = incre_step3;        
78         incre_step3 = incre_step4;
79         incre_step4 = incre_step5;
80         incre_step5 = incre_step6;
81         incre_step6 = incre_step7;
82         incre_step7 = temp;
83         count = 0;
84         
85     }
86 }
soft_Pwm.c

 

逻辑分析仪数据如下：

https://files.cnblogs.com/alimy/softPWM_logicdata.zip

posted @ 2013-12-22 15:37  Alimy  阅读(1060)  评论(0)  编辑  收藏  举报