通过EXIT按键调节PWM的占空比

justinddd

想用EXIT按键功能调节PWM的占空比，定时周期为1000，占空比有500,250，但按下按键由500变250时，输出的方波是这样的   ___|￣|_|￣|___,并不是我想要的占空比为250的方波

1. void TIM3_Mode_Config(int pulse)
   
2. {
   
3.         TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
   
4.         TIM_OCInitTypeDef  TIM_OCInitStructure;
   
5.        
   
6.         u16 t[] = {500,250};
   
7. 
   
8. 
   
9. 
   
10.        
    
11.          /* Time base configuration */                 
    
12.   TIM_TimeBaseStructure.TIM_Period = 999;
    
13.   TIM_TimeBaseStructure.TIM_Prescaler = 0;
    
14.   TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1 ;
    
15.   TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    
16.   TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
    
17. 
    
18.   /* PWM1 Mode configuration: Channel1 */
    
19.   TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    
20.   TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;       
    
21.   TIM_OCInitStructure.TIM_Pulse = t[0];
    
22. 
    
23.   TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    
24.   TIM_OC1Init(TIM3, &TIM_OCInitStructure);
    
25.   TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
    
26.        
    
27.         TIM_ARRPreloadConfig(TIM3, ENABLE);
    
28. 
    
29.        
    
30.         /* TIM3 enable counter */
    
31.   TIM_Cmd(TIM3, ENABLE);
    
32. }       

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1. #include "stm32f10x_it.h"
   
2. #include "pwm.h"
   
3. 
   
4. extern TIM_OCInitTypeDef  TIM_OCInitStructure;
   
5. extern u16 t[];
   
6. extern void TIM3_Mode_Config(void);

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1. void EXTI15_10_IRQHandler(void)
   
2. {
   
3.     if(EXTI_GetITStatus(EXTI_Line13) != RESET)
   
4.    {
   
5.        while(1)
   
6.       {
   
7.          TIM_OCInitStructure.TIM_Pulse = t[1];          
   
8.          TIM3_Mode_Config();
   
9.        }                       
   
10.                
    
11.                
    
12.     }  
    
13. }

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1. #include "stm32f10x.h"
   
2. #include "pwm.h"
   
3. #include "exit.h"
   
4. 
   
5. 
   
6. 
   
7. 
   
8. int main(void)
   
9. {       
   
10.         EXTI_PC13_Config();
    
11.         TIM3_PWM_Init();
    
12. 
    
13. }

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