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标题: PWM输出 [打印本页]

作者: 张衍波 时间: 2015-4-8 13:25
标题: PWM输出
#define MAIN_C
#include "includes.h"
/***************************/
/*PWM*/
/*晶振为4MHz*/
/*利用Timer1的OC1A脚输出占空比可调的信号*/
/*通过按键控制OCR1A的值*/
/***************************/

#define PwmOut    PD5    //A通道的PWM输出
#define OCR       OCR1A
#define KeyUp    PA0    //增大PWM值的按键
#define KeyDown PA1    //减小PWM值的按键
#define Above    PA2    //设置位值过高指示
#define Below    PA3    //设置位值过低指示
#define STEP    64    //定义按键时的步进值
int OcrReg = 1024;       //OCR1A初始值
int Icr1Reg = 0x7ff;    //PWM的计数顶部值  Icr1Reg = 2047
//unsigned char *show = "0000";
unsigned char temp;

void init(void) //初始化函数
{
//比较匹配时清零，计数到最大时置位OC1A
TCCR1A |= (1<<COM1A1)|(1<<WGM11);
//11位分辨率，快速PWM模式，使用系统时钟作为计数时钟
TCCR1B |= (1<<WGM13)|(1<<WGM12)|(1<<CS10);
ICR1 = Icr1Reg;
OCR = 0 ;
DDRD  |= (1<<PwmOut);       //置PWM为输出
DDRA  |= (1<<Above)|(1<<Below);    //指示灯定义为输出
DDRA  &= ~((1<<KeyUp)|(1<<KeyDown)); //按键定义为输入
PORTA |= (1<<KeyUp)|(1<<KeyDown); //按键开启上拉
PORTA |= (1<<Above)|(1<<Below);    //关闭两个指示灯
//TIMSK |= (1<<OCIE1A); //允许计数器比较匹配中断
//SREG  |= (1<<7); //开全局中断
}

void  ShowValue(int value)
{
unsigned char *temp = "0000";
temp[0] = value/1000 + 0x30;
value = value%1000;
temp[1] = value/100 +0x30;
value = value%100;
temp[2] = value/10 + 0x30;
value = value%10;
temp[3] = value + 0x30;
ClearLine(2);
LCD_DisplayString(2,1,"OCR1A = ");
LCD_DisplayString(2,9,temp);
}

void main(void)
{
unsigned char i;
init();
Init_LCD();
OCR = OcrReg;
LCD_DisplayString(1,1,"PWM test");
LCD_DisplayString(2,1,"OCR1A = ");
ShowValue(OcrReg);
while(1)
{
      if(!(PINA&(1<<KeyUp)))
      {
         delay_nms(10); //按键消抖
         if(!(PINA&(1<<KeyUp)))
         {
            while(!(PINA&(1<<KeyUp)));  //等待按键释放
            if(OcrReg >= (Icr1Reg+1))
            {
                  for(i=0;i<5;i++)
                  {
                     PORTA ^= (1<<Above);
                     delay_nms(200);
                  }
                  ClearLine(2);
                  LCD_DisplayString(2,1,"Value MAX!");
            }
            else
            {
                  PORTA |= (1<<Above);
                  OcrReg += STEP;
                  OCR = OcrReg;
                  ShowValue(OcrReg);
            }
         }
      }
      if(!(PINA&(1<<KeyDown)))
      {
         delay_nms(10); //按键消抖
         if(!(PINA&(1<<KeyDown)))
         {
            while(!(PINA&(1<<KeyDown)));  //等待按键释放
            if(OcrReg <= 0)
            {
                  for(i=0;i<5;i++)
                  {
                     PORTA ^= (1<<Below);
                     delay_nms(200);
                  }
                  ClearLine(2);
                  LCD_DisplayString(2,1,"Value MIN!");
            }
            else
            {
                  PORTA |= (1<<Below);
                  OcrReg -= STEP;
                  OCR = OcrReg;
                  ShowValue(OcrReg);
            }
         }
      }
}
}

//比较中断子程序，可以用来产生正弦波
/*#pragma vector = TIMER1_COMPA_vect
__interrupt void CompA_isr( void )
{

OcrReg =  st[j];
OCR = OcrReg;
j++;
if(j>88)
{
      j = 0;
}
}*/
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