关于STM32动态改变PWM的问题相当奇葩

只看该作者 · 2014-4-2 21:28

初始化代码如下

void TIM_PWM_Configuration(void)
{
extern TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
extern TIM_OCInitTypeDef  TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

TIM_TimeBaseStructure.TIM_Period = 7200;       //Òç³öÊ±¼ä((1+TIM_Prescaler )/72M)*(1+TIM_Period ) 7200 19999  2s 999  71  1ms
TIM_TimeBaseStructure.TIM_Prescaler = 19999;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

TIM_OCInitStructure.TIM_Pulse = 3600;
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);

/*TIM_OCInitStructure.TIM_Pulse = 3600;
TIM_OC2Init(TIM3, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);

TIM_OCInitStructure.TIM_Pulse = 3600;
TIM_OC3Init(TIM3, &TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);

TIM_OCInitStructure.TIM_Pulse = 3600;
TIM_OC4Init(TIM3, &TIM_OCInitStructure);
TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable); */

TIM_ARRPreloadConfig(TIM3, ENABLE);

TIM_Cmd(TIM3, ENABLE);

void GPIO_init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA  |RCC_APB2Periph_GPIOB| RCC_APB2Periph_AFIO, ENABLE);
//PWM_CH init
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 |
                              GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);


GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 |
                                 GPIO_Pin_1;
GPIO_Init(GPIOB,&GPIO_InitStructure);

//U1_init
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;  //tx
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; //rx
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

}

只看该作者 · 2014-4-2 21:30

void PWM_Duty_Cycle_Set_4_CH(unsigned int CH1,unsigned int CH2,unsigned int CH3, unsigned int CH4)
{

TIM_OCInitStructure.TIM_Pulse = CH1;
TIM_OC1Init(TIM3, &TIM_OCInitStructure);

}

当在程序中用这个函数改变PWM的占空比时 PWM的输出电压只有1.7V左右而未用这个函数动态改变占空比时 PA6的电压有3.3V。。。。

只看该作者 · 2014-4-2 21:32

int main(void)
{
RCC_Config_72M();
  GPIO_init();
  TIM_PWM_Configuration();
USART1_Configuration();
NVIC_Configuration();
while(1)
{
if(key==0)PWM_Duty_Cycle_Set_4_CH(3600,0,0,0);
                              else  PWM_Duty_Cycle_Set_4_CH(100,0,0,0);
}
主函数式这样的
}

只看该作者 · 2014-4-2 21:35

不知道为什么啊如果把TIM3整个关了再开 PWM的电压又正常了。。。但是这样就降低了实时性了

关于STM32动态改变PWM的问题 相当奇葩

关于STM32动态改变PWM的问题相当奇葩