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	 > 嵌入式系統(tǒng) > 設(shè)計應(yīng)用 > 關(guān)于動態(tài)改變STM32 PWM占空比的問題
          
    
          

          

          


	
	
	

          
	
          
		
          
			
          關(guān)于動態(tài)改變STM32 PWM占空比的問題
          
						
          
				作者：
				時間：2016-11-25
				來源：網(wǎng)絡(luò)
				
				
				
				
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          while (1)
          {
           Delay(500);
            if(CCR4_Val>1)
            {
            CCR4_Val--;
            TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
            TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
            TIM_OCInitStructure.TIM_Pulse = CCR4_Val;
            TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

            TIM_OC4Init(TIM3, &TIM_OCInitStructure);
            }
            else
            {
            CCR4_Val=990;
            TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
            TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
            TIM_OCInitStructure.TIM_Pulse = CCR4_Val;
            TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

            TIM_OC4Init(TIM3, &TIM_OCInitStructure);
            }
          }
          }
          在主程序里改變對比值來改變PWM占空比，上面的程序是不是太笨了，有沒有其他方法，請高手指點(diǎn)
          MCU2008 (2008-9-12 10:43:53)
          是太笨了...
          sunke9 (2008-9-12 10:47:56)
          我的用法和你一樣
          while (1)
          {
            Delay(0x0000FFFF);
            CCR1_Val = ADC_ConvertedValue*4;
            CCR2_Val = 16000 - ADC_ConvertedValue*4;
              
            TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
            TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
            TIM_OCInitStructure.TIM_Pulse = CCR1_Val;
            TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

            TIM_OC1Init(TIM2, &TIM_OCInitStructure);

            TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);

          }
          nomoneyiv (2008-9-12 11:29:08)
          在中斷里搞！
          nomoneyiv (2008-9-12 11:33:22)
          比如：
          void TIM1_UP_IRQHandler(void)
          {
           TIM1_SetCompare1(pwm_val_c1);
            TIM1_SetCompare3(pwm_val_c3);
            TIM1_SetCompare2(pwm_val_c2);
           TIM1_ClearITPendingBit(TIM1_IT_Update);

          }
          然后在主循環(huán)里，更改值
          pwm_val_c1++;  之類的。
          020411 (2008-9-12 15:21:42)
          謝謝STM32青菜
          yemingxp (2008-9-12 20:02:26)
                
          aleyn (2008-9-15 14:05:15)
          此貼最終解惑者是誰？
          sw笨笨 (2009-2-24 07:31:01)
          while (1)               //無限循環(huán)
          {
          CCR4_Val=CCR4_Val+0x1000;     //變量遞增
          if(CCR4_Val >= 0xffff) CCR4_Val=0;  //變量歸零

          TIM_SetCompare4(TIM3, CCR4_Val);  //變更長度
          Delay(0xffff);                //延時
          }
          selina (2009-12-12 15:28:56)
          好像只能在中斷內(nèi)做吧
          wslaurora (2010-1-26 15:48:33)
          通過tim更新時間觸發(fā)DMA傳輸（循環(huán)模式），豈不是更簡單？
           
              TIM_DMACmd(TIM1, TIM_DMA_Update, ENABLE);


            DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)TIM1_CCR1_Address;   //TIM1通道1外設(shè)捕獲/比較寄存器首地址
            DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)SRC_Buffer; //內(nèi)存數(shù)據(jù)緩存首地址
              DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;   //外設(shè)作為數(shù)據(jù)傳輸?shù)哪康?br />  DMA_InitStructure.DMA_BufferSize = 256;   //DMA緩存大小為256

          
				
            
                
			
							
          
                
			              
              
            
          
		
          
		
          
		
          
		
          
		
          
			
            
				
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