废话不多说直接上程序仿真图
仿真工程文件下载：
PWM.rar
(25.81 KB, 下载次数: 101)
单片机源程序：
- #include <reg52.h>
- unsigned char HighRH = 0; //高电平重载值的高位
- unsigned char HighRL = 0; //高电平重载值的低位
- unsigned char LowRH = 0; //低电平重载值的高位
- unsigned char LowRL = 0; //低电平重载值的低位
- unsigned int cnt=0; //记录T1中断次数
- unsigned int i=0;
- unsigned char dc=0;//PWM占空比
- unsigned char fr=0; //PWM频率
- unsigned char out=0; //PWM输出指示
- sbit PWMOUT=P3^7; //PWM输出端口
- void ConfigPWM();
- void ClosePWM();
- sbit k0=P1^0; //占空比+5
- sbit k1=P1^1; //占空比-5
- sbit k2=P1^2; //频率+
- sbit k3=P1^3; // 频率-
- sbit k4=P1^4; //输出PWM
- sbit k5=P1^5; //停止输出PWM
- unsigned char code LEDChar[]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
- unsigned char code LEDBuff[]={0xF7,0xFB,0x7F,0xBF};
- void delay(int ms) //延时函数用于数码管的显示
- {
- unsigned int x,y;
- for(x=ms;x>0;x--)
- for(y=110;y>0;y--);
- }
- void LEDstate()
- {
- P0=LEDBuff[0];
- P2=LEDChar[dc%10];
- delay(3);
- P0=LEDBuff[1];
- P2=LEDChar[dc/10];
- delay(3);
- P0=LEDBuff[2];
- P2=LEDChar[fr%10];
- delay(3);
- P0=LEDBuff[3];
- P2=LEDChar[fr/10];
- delay(3);
-
- }
- void Key(void)
- {
- if(out==0)
- {
- if(k0==0) //停止输出波形才能进行调整
- {
- if(dc<100) //占空比+5
- dc+=5;
- while(k0==0);
- }
- if(k1==0) //占空比-5
- {
- if(dc=0)
- dc-=5;
- while(k1==0);
- }
-
- if(k2==0) //频率+1
- {
- fr+=10;
- while(k2==0);
- }
- if(k3==0) //频率-1
- {
- if(fr!=0)
- fr-=10;
- while(k3==0);
- }
- }
- if(k4 == 0) //输出波形
- out =1;
- if(k5 == 0) //停止输出波形
- out =0;
- }
- void main()
- {
-
-
-
- while (1)
- {
- LEDstate();
- Key();
- ConfigPWM(); //调用PWM配置函数
- /* if(out==0)
- ClosePWM();
- */
-
- }
- }
- /* 配置PWM,fr频率,dc-占空比 */
- void ConfigPWM()
- {
- unsigned int high, low;
- unsigned long tmp;
-
- tmp = (11059200/12)/100/fr; //计算一个周期所需要的计数值
- high = (tmp*dc)/100; //计算高电平所需要的计数值
- low = tmp - high; //计算低电平所需要的计数值
- high = 65536 - high + 12; //计算高电平的重载值并补偿中断延时
- low = 65536 - low + 12; //计算低电平的重载值并补偿中断延时
- HighRH = (unsigned char)(high>>8); //高电平重载值拆分高低字节
- HighRL = (unsigned char)high;
- LowRH = (unsigned char)(low>>8); //低电平重载值拆分高低字节
- LowRL = (unsigned char)low;
- TMOD &= 0xF0; //清除T0的控制段?
- TMOD |= 0x01; //T0为模式1
- TH0 = HighRH; //加载T0重载值
- TL0 = HighRL;
- ET0 = 1; //使能T0中断
- TR0 = 1; //启动T0
- EA = 1; //开关总使能
- PWMOUT=1; //输出高电平
- }
- /*关闭PWM */
- void ClosePWM()
- {
- TR0 =0; //停止定时器
- ET0 =0; //禁止中断
- PWMOUT=1; //输出高电平
- }
- /* T0中断服务程序，产生PWM波 */
- void InterruptTimer0() interrupt 1
- {
- if (PWMOUT==1) //当输出为高电平，加载低电平值并输出低电平
- {
- TH0 = LowRH;
- TL0 = LowRL;
- PWMOUT = 0;
- }
- else //当输出为低电平，加载高电平值并输出高电平
- {
- TH0 = HighRH;
- TL0 = HighRL;
- PWMOUT = 1;
- }
- }
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